Dark Sky Library

Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study) (2018). “Both prostate and breast cancer were associated with high estimated exposure to outdoor ALAN in the blue-enriched light spectrum.” 

The mystery of breast cancer (2015 The Conversation) “…Electric light at night can trick the body into daytime physiology in which the hormone melatonin is suppressed; and melatonin has been shown to have a strong inhibitory effect on human breast tumors growing in rats.” 

Hormone Melatonin Slows Breast Cancer (2003 Web MD) 

Artificial Lighting in the Industrialized World: Circadian Disruption and Breast Cancer (2006 ResearchGate.net). “There is evidence in humans that the endogenous melatonin rhythm is stronger for persons in a bright-day environment than in a dim-day environment; and the light intensity necessary to suppress melatonin at night continues to decline as new experiments are done. Melatonin suppression can increase breast tumorigenesis in experimental animals, and altering the endogenous clock mechanism may have downstream effects on cell cycle regulatory genes pertinent to breast tissue development and susceptibility. Therefore, maintenance of a solar day-aligned circadian rhythm in endogenous melatonin and in clock gene expression by exposure to a bright day and a dark night, may be a worthy goal. However, exogenous administration of melatonin in an attempt to achieve this goal may have an untoward effect given that pharmacologic dosing with melatonin has been shown to phase shift humans depending on the time of day it’s given. Exogenous melatonin may therefore contribute to circadian disruption rather than alleviate it” [emphasis added]. 

Nighttime light level co-distributes with breast cancer incidence worldwide (2010 Dynamics.org). “We found a significant positive association between population LAN [light at night] level and incidence rates of breast cancer. There was no such an association between LAN level and colorectal, larynx, liver, and lung cancers. A sensitivity test, holding other variables at their average values, yielded a 30–50% higher risk of breast cancer in the highest LAN exposed countries compared to the lowest LAN exposed countries.” 

Light Pollution as a New Risk Factor for Human Breast and Prostate Cancers [technical book] (2013). Abraham Haim, Boris A. Portnov. 

Melatonin: an inhibitor of breast cancer (2015 CircadianLight.com) 

Light at Night Co-distributes with Incident Breast But Not Lung Cancer in the Female Population of Israel (2008 CircadianLight.com). “The analysis yielded an estimated 73% higher breast cancer incidence in the highest LAN exposed.”  

Breast cancer and circadian disruption from electric lighting in the modern world (2014 American Cancer Society) 

The Light-Cancer Connection (2011 Prevention.com) 

How Society’s Light Pollution affects Human Breast Cancer (2013 FAU.edu). “The problem is that even weak amounts of light can impede our pineal gland from creating the beneficial melatonin. Without melatonin, other glands produce their hormones unchecked, which lead to ever greater breast cancer rates.” 

Inverse association between breast cancer incidence and degree of visual impairment in Finland (1999 Nature). “Breast cancer risk decreased by degree of visual impairment (P for trend 0.04) which suggests a dose–response relationship between visible light and breast cancer risk.” 

Circadian and Melatonin Disruption by Exposure to Light at Night Drives Intrinsic Resistance to Tamoxifen Therapy in Breast Cancer (2014 American Association for Cancer Research). “Moreover, light exposure at night (LEN) suppresses the nocturnal production of melatonin that inhibits breast cancer growth… Strikingly, our results also showed that melatonin acted both as a tumor metabolic inhibitor and a circadian-regulated kinase inhibitor to reestablish the sensitivity of breast tumors to tamoxifen and tumor regression. Together, our findings show how dLEN [dim light exposure at night]-mediated disturbances in nocturnal melatonin production can render tumors insensitive to tamoxifen.” 

Night Shift Work, Light at Night, and Risk of Breast Cancer (2001 Journal of the National Cancer Institute). “Exposure to light at night may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin by the pineal gland, which, in turn, could increase the release of estrogen by the ovaries… The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer.” 

Melatonin-Depleted Blood from Premenopausal Women Exposed to Light at Night Stimulates Growth of Human Breast Cancer Xenografts in Nude Rats (2005 American Association for Cancer Research). “These results are the first to show that the tumor growth response to exposure to light during darkness is intensity dependent and that the human nocturnal, circadian melatonin signal not only inhibits human breast cancer growth but that this effect is extinguished by short-term ocular exposure to bright, white light at night.” 

Breast Cancer and Circadian Disruption From Electric Lighting in the Modern World (2014 American Cancer Society). “A convergence of research in cells, rodents, and humans suggests that the health consequences of circadian disruption may be substantial.” 

Light at night and breast cancer incidence in Connecticut: An ecological study of age group effects (2016 Science Direct). “Light level emerged as a significant predictor of breast cancer incidence… The association of LAN with breast cancer incidence weakened with age; the association was strongest among premenopausal women.” 

Ocular input for human melatonin regulation: relevance to breast cancer (2002 Neuro endocrinology letters). “Under highly controlled exposure circumstances, less than 1 lux of monochromatic light elicited a significant suppression of nocturnal melatonin.” 

Circadian disruption, shift work and the risk of cancer: a summary of the evidence and studies in Seattle (2006 Cancer Causes & Control). “Epidemiologic studies are now beginning to emerge suggesting that women who work at night, and who experience sleep deprivation, circadian disruption, and exposure to light-at-night are at an increased risk of breast cancer, and possibly colorectal cancer as well.” 

Light during darkness and cancer: relationships in circadian photoreception and tumor biology (2006 Cancer Causes & Control). “Empirical data has increasingly supported the hypothesis that higher risk of breast cancer in industrialized countries is partly due to increased exposure to light at night.”

Working against our endogenous circadian clock: Breast cancer and electric lighting in the modern world (2009). “Based on the fact that light during the night can suppress melatonin, and also disrupt the circadian rhythm, it was proposed in 1987 that increasing use of electricity to light the night accounts in part for the rising risk of breast cancer globally. Predictions from the theory include: non-day shift work increases risk, blindness lowers risk, long sleep duration lowers risk, and population level community nighttime light level co-distributes with breast cancer incidence. Thus far, studies of these predictions are consistent in support of the theory.” 

LIGHT POLLUTION: Light at Night and Breast Cancer Risk Worldwide (2010 Environmental Health Perspectives). “Do not take melatonin tablets unless directed by a physician. The spike in circulating melatonin may actually worsen, not alleviate, circadian disruption.” 

Light at night and melatonin have opposite effects on breast cancer tumors in mice assessed by growth rates and global DNA methylation (2013 Chronobiology International). “Light-at-night (LAN) is a worldwide problem co-distributed with breast cancer prevalence. We hypothesized that exposure to LAN is coincided with a decreased melatonin (MLT) secretion level, followed by epigenetic modifications and resulted in higher breast cancer tumors growth-rate. Accordingly, we studied the effect of LAN exposure and exogenous MLT on breast cancer tumors growth-rate. 4T1 cells were inoculated into BALB/c short day-acclimated mice, resulting in tumors growth. Growth rates were followed under various light exposures and global DNA methylations were measured. Results demonstrated the positive effect of LAN on tumors growth-rate, reversed by MLT through global DNA methylation.” 

Antiproliferative and pro-apoptotic activity of melatonin analogues on melanoma and breast cancer cells (2017 Oncotarget). “Melatonin plays different physiological functions ranging from the regulation of circadian rhythms to tumor inhibition, owing to its antioxidant, immunomodulatory and anti-aging properties. Due to its pleiotropic functions, melatonin has been shown to elicit cytoprotective processes in normal cells and trigger pro-apoptotic signals in cancer cells.” 

Sleep duration, melatonin and breast cancer among Chinese women in Singapore (2008 Carcinogenesis). “Melatonin levels were 42% higher in those with 9+ versus those with ≤6 h of sleep. Conclusion: Sleep duration may influence breast cancer risk, possibly via its effect on melatonin levels.” 

Risk of breast cancer among Norwegian women with visual impairment (2001 Nature). “Experimental studies suggest that melatonin has a protective effect against breast cancer. Exposure to light suppresses melatonin secretion, but to a lesser degree in totally blind persons. … Our findings give support to the ‘melatonin hypothesis’.” 

Urinary Excretion of Melatonin and Association with Breast Cancer: Meta-Analysis and Review of the Literature (2014 Karger). “Melatonin is an endocrine hormone secreted by the pineal gland during night hours that provides several biological functions in the circadian rhythm of humans. Due to anti-estrogenic properties, melatonin is considered to exhibit a protective role against the development of breast cancer (BC). Moreover, disruption of melatonin production through environmental influences, such as night work, is assumed to be a risk factor for BC. … Conclusion: On the basis of the results of our meta-analysis, melatonin is likely to affect BC occurrence in women. However, methodological dissonances may require further studies.” 

Effect of constant light on DMBA mammary tumorigenesis in rats (2000 Science Direct). “A study of light, and mammary tumorigenesis was conducted in rats. … Constant light was clearly demonstrated to have a profound effect on mammary tissue development. Although virgin, the majority of the LL rats (29/50) had gross evidence of lactation at 141 days of age. None of the LD rats (0/50) showed evidence of milk production. These results suggest that constant light not only substantially accelerated mammary gland development, but pushed development of the tissue past the stage normally observed in virgin animals (to the lactation stage).” 

Exposure to light-at-night increases the growth of DMBA-induced mammary adenocarcinomas in rats (2006 Science Direct). “Animals exposed to light-at-night, especially those under a constant dim light during the darkness phase, showed: (a) significantly higher rates of tumor growth as well as lower survival than controls, (b) higher concentration of serum estradiol, and (c) lower nocturnal excretion of 6-sulfatoxymelatonin, without there being differences between nocturnal and diurnal levels. These results suggest that circadian and endocrine disruption induced by light pollution, could induce the growth of mammary tumors.” 

Light and the City: Breast Cancer Risk Factors Differ Between Urban and Rural Women in Israel (2016 Integrative Cancer Therapies). “These data support the idea that indoor and outdoor nighttime light exposures differ between urban and rural women. Therefore, we suggest that women can influence BC risk and incidence by applying protective personal lighting habits.” 

High Incidence of Breast Cancer in Light-Polluted Areas with Spatial Effects in Korea (2016 Asian Pacific Journal of Cancer Prevention). “We suggest that a decrease in ALAN could reduce breast cancer more than expected because of spatial effects.” 

Outdoor light at night linked with increased breast cancer risk in women (2017 Harvard School of Public Health). “Women exposed to the highest levels of outdoor light at night—those in the top fifth—had an estimated 14% increased risk of breast cancer during the study period, as compared with women in the bottom fifth of exposure, the researchers found. As levels of outdoor light at night increased, so did breast cancer rates.” 

Night shift work and breast cancer: a pooled analysis of population-based case–control studies with complete work history (2018 European Journal of Epidemiology). “These results support the hypothesis that night shift work increases the risk of breast cancer in pre-menopausal women, particularly those with high intensity and long duration of exposure. Risk difference between pre- and post-menopausal women deserves further scrutiny.” 

Urinary Melatonin Levels, Sleep Disruption, and Risk of Prostate Cancer in Elderly Men (2015 Science Direct). “Men with morning aMT6s levels below the median had a fourfold statistically significant increased risk for advanced disease compared with men with levels above the median (hazard ratio: 4.04; 95% confidence interval, 1.26–12.98).” 

Global Co‐Distribution of Light at Night (LAN) and Cancers of Prostate, Colon, and Lung in Men (2009 Chronobiology International). “We found a significant positive association between population exposure to LAN [light at night] and incidence rates of prostate cancer, but no such association with lung cancer or colon cancer.” 

Circadian Disruption and Prostate Cancer Risk: An Updated Review of Epidemiological Evidences (2017 Cancer Epidemiology, Biomarkers & Prevention). “Evidence of a possible association between night shift work and prostate cancer remains to date inconclusive even though results of a recent meta-analysis concluded to a 24% increase risk of prostate cancer.”

Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases (2015 Chronobiology International). “Routine exposure to artificial light at night (ALAN) in work, home, and community settings is linked with increased risk of breast and prostate cancer (BC, PC) in normally sighted women and men… However, ALAN [artificial light at night] exposure occurs concomitantly with almost complete absence of daytime sunlight, whose blue-violet (446-484 nm λ) spectrum synchronizes the CTS and whose UV-B (290-315 nm λ) spectrum stimulates vitamin D synthesis.” 

Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment (2015 Chronobiology International). “It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright [emphasis added].” 

Carcinogenicity of shift-work, painting, and fire-fighting (2014 The Lancet) 

Preventable Exposures Associated With Human Cancers (2011 Oxford University Press) 

Artificial Light at Night of Different Spectral Compositions Differentially Affects Tumor Growth in Mice: Interaction With Melatonin and Epigenetic Pathways (2018 Cancer Control). “Lighting technology is rapidly advancing toward shorter wavelength illuminations that offer energy-efficient properties. Along with this advantage, the increased use of such illuminations also poses some health challenges, particularly breast cancer progression. Here, we evaluated the effects of artificial light at night (ALAN) of 4 different spectral compositions (500-595 nm) at 350 Lux on melatonin suppression by measuring its urine metabolite 6-sulfatoxymelatonin, global DNA methylation, tumor growth, metastases formation, and urinary corticosterone levels in 4T1 breast cancer cell-inoculated female BALB/c mice. The results revealed an inverse dose-dependent relationship between wavelength and melatonin suppression. Short wavelength increased tumor growth, promoted lung metastases formation, and advanced DNA hypomethylation, while long wavelength lessened these effects. Melatonin treatment counteracted these effects and resulted in reduced cancer burden. The wavelength suppression threshold for melatonin-induced tumor growth was 500 nm. These results suggest that short wavelength increases cancer burden by inducing aberrant DNA methylation mediated by the suppression of melatonin. Additionally, melatonin suppression and global DNA methylation are suggested as promising biomarkers for early diagnosis and therapy of breast cancer. Finally, ALAN may manifest other physiological responses such as stress responses that may challenge the survival fitness of the animal under natural environments” [emphasis added]. 

Artificial light-at-night – a novel lifestyle risk factor for metabolic disorder and cancer morbidity (2017 Journal of Basic and Clinical Physiology and Pharmacology). “In this review, we first provide an overview on the molecular feedback loops that generate the circadian regulation and how circadian disruption by ALAN can impose adverse impacts on public health, particularly metabolic disorders and breast cancer development.” 

Global Co‐Distribution of Light at Night (LAN) and Cancers of Prostate, Colon, and Lung in Men (2008 Chronobiology International ). “We found a significant positive association between population exposure to LAN and incidence rates of prostate cancer, but no such association with lung cancer or colon cancer. … An analysis holding other variables at average values across the 164 countries yielded a risk of prostate cancer in the highest LAN‐exposed countries 110% higher than in the lowest LAN exposed countries.” 

Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study) (2018 Environmental Health Perspectives). “Night shift work, exposure to light at night (ALAN) and circadian disruption may increase the risk of hormone-dependent cancers. … Conclusion: Both prostate and breast cancer were associated with high estimated exposure to outdoor ALAN in the blue-enriched light spectrum.” 

Cancer all-clear for night work based on ‘bad science’, warn scientists (2016 Hazards Magazine). “It seems like bad science”, she said. Given the limitations of the Travis study it was “not surprising” the study found no effect. She said these “many shortcomings – as unanimously asserted by my colleagues and myself – preclude it from making the conclusion that there is no association between night work and breast cancer risk.” 

Medical Effects of Light Pollution (2012). “In fact, researchers now estimate that up to 30% of breast cancers are secondary to light at night suppressing circadian rhythm.” 

Chronic Disruptions to Circadian Rhythms Promote Tumor Growth, Reduce Efficacy of Therapy (2019 Sleep Review Magazine) 

Melatonin: a possible link between the presence of artificial light at night and reductions in biological fitness (2015 The Royal Society Publishing). “Melatonin supplementation was able only partially to mitigate the detrimental effects of LAN: it did not improve survival or fecundity…” 

Light at night can disrupt circadian rhythms in children – are there long-term risks? (2018 The Conversation)

Artificial light at night can make us fat (2016, Israel 21). “This represents the first time that anyone has shown an association between obesity and light pollution on such a large scale…” 

Does Lack of Sleep Make People More Violent? (2016 Psychology Today) 

Are we sleep-deprived or just darkness-deprived? (2016 The Conversation) “So whether awake or not, these subjects produced melatonin, and maintained nighttime physiology, for the long duration of dark.” 

In Eyes, a Clock Calibrated by Wavelengths of Light (2011 New York Times). “Light works as if it’s a drug, except it’s not a drug at all…” 

A dark night is good for your health (2016 The Conversation) “The changes that result from exposure to electric light at night have biological connections to disease and conditions that are common in the modern world today including obesity, diabetes, cancer and depression.” 

Make lighting healthier (2018 Nature). “As a lighting researcher and designer, I am convinced that the costs of this transition [to LEDs] far outweigh the benefits for human health and the environment. Because the world’s urban population spends more time indoors under artificial lighting than in daylight, the health impacts are already evident.” 

Light Rhythms (2009 ExperienceLife.com). “Since the advent of electricity, we haven’t been exposed to enough darkness.” Meanwhile, by spending most of our waking hours indoors and away from natural sunlight, we’re also often underexposed to the wavelengths of light that stimulate our natural rhythms. 

Welcome to the Wild West (2019 Lighted Magazine). “The industry is racing to offer color-tuning LEDs and promising outcomes that they shouldn’t be. Years ago, the FDA was put in place to regulate the pharmaceutical industry and there are parallels here; if we’re not careful about making unsubstantiated health claims, a lawsuit may someday raise the issue of lighting and health to Federal attention.” 

Inside The Vexing Quest To Safely Light Our Modern Lives (2017 GOOD Magazine). “Any light between dusk and bedtime will likely have a biological effect, but by minimizing the intensity and blue-light content, you can minimize these effects on sleep.” But as it turns out, giving the right light to people during the day may be just as important as removing it at night. 

Men With Low Sex Drive, Testosterone, May Find Relief With Light Therapy (2016 Medical Daily). “After two weeks, the men who received genuine light therapy not only had higher amounts of testosterone in their blood, but they also reported a substantial increase in sexual desire and function compared to the placebo group.” 

The light therapeutic (2014 The Economist). 

Let there be light: Helping people through dark days (2015 BBC News). “Unlike standard lighting that tends to give off a yellow hue, the so-called ‘full spectrum’ lights installed in these classrooms give off a greater proportion of blue wavelengths. These have been shown to have a greater effect on regulating the body clock if delivered early in the morning. It works by suppressing the production of the hormone melatonin, which causes drowsiness.” 

Scientific Study Demonstrates Positive Effects of Daylight LED on Visual Comfort, Melatonin, Mood, Waking Performance, and Sleep (2019 LED Professional) ”LED light sources with a spectrum close to natural sunlight produced better visual comfort, more alertness, and happier moods in the morning and evening among the test participants, compared to those exposed to conventional spectrum LEDs.” 

The time is now for the IoT [internet of things] to advance lighting for wellbeing (2018 LEDs Magazine). “Because most people have limited control over the lighting they experience in public buildings such as workplaces or schools, the home serves as the hub for a healthy life, essentially by default.”

Speakers cover circadian disruption to healthcare assessment at new conference (2017 LEDs Magazine). “At the LEDs Magazine Lighting for Health and Wellbeing Conference, speakers covered topics ranging from the perils of shift work and nighttime lighting to the up and down sides of blue spectral energy, as well as the need for better lighting in healthcare facilities, reports Maury Wright.”

Researchers present circadian metrics and health impact of LED light at HCL conference (2018 LEDs Magazine). “…Interesting talks focused on characterizing lighting for health and the direct positive and negative impacts of artificial light on health.” 

Sleeping with Low Levels of Artificial Light at Night Increases Systemic Inflammation in Humans (2019 Oxford Academic). “Sleeping with ALAN [artificial light at night] for seven days significantly increased hsCRP levels and modestly increased depression scores in humans.” 

A one-year study of the macular pigment: the effect of 140 days of a lutein supplement (1997 Experimental Eye Research). “The mean increases in the macular pigment optical density were 39% and 21% in the eyes of the two subjects respectively. In conclusion, the modest period of supplementation has been estimated to have produced in the subjects a 30 to 40% reduction in blue light reaching the photoreceptors, Bruch’s membrane, and the retinal pigment epithelium, the vulnerable tissues affected by AMD.” 

Lighting for the human circadian clock: recent research indicates that lighting has become a public health issue (2004 Medical Hypotheses.). “These studies suggest that the proper use and color of indoor and outdoor lighting is important to the health of both humans and ecosystems. Lighting fixtures should be designed to minimize interference with normal circadian rhythms in plants and animals.”

Outdoor artificial light at night, obesity, and sleep health: Cross-sectional analysis in the KoGES study (2016 Chronobiology International). “The findings of our study provide epidemiological evidence that outdoor ALAN [artificial light at night] is significantly related to obesity.” 

Exposure to dim artificial light at night increases REM sleep and awakenings in humans (2015 Journal of Biological and Medical Rhythm Research). “We found that dALAN [dim artificial light at night] during sleep affects sleep structure. Exposure to dALAN during sleep increases the frequency of arousals, amount of shallow sleep and amount of REM sleep. This suggests adverse effects of dALAN during sleep on sleep quality and suggests the need to avoid exposure to dALAN during sleep.” 

Phototherapy and orange-tinted goggles for night-shift adaptation of police officers on patrol (2012 Chronobiology International). “Orange-tinted goggles have been shown to block the melatonin-suppressing effect of light significantly more than neutral gray density goggles… Reaction speed dropped, and subjective alertness decreased throughout the night shift in both groups (p < .001). Reaction speed decreased throughout the work week in the control group (p ≤ .021), whereas no difference was observed in the intervention group.” 

Light, sleep and circadian rhythms in older adults with Alzheimer’s disease and related dementias (2017 Neurodegenerative Disease Management). “Recent research showing that the circadian system is maximally sensitive to short-wavelength light opens the way for the potential application of lower, more-targeted light intensities to maximize compliance and individualize light dose/timing in therapeutic settings.” 

Limiting the impact of light pollution on human health, environment and stellar visibility (2011 Science Direct). “Migration from the now widely used sodium lamps to white lamps (MH and LEDs) would produce an increase of pollution in the scotopic and melatonin suppression bands of more than five times the present levels, supposing the same photopic installed flux” [emphasis added]. 

The shift work and health research agenda: Considering changes in gut microbiota as a pathway linking shift work, sleep loss and circadian misalignment, and metabolic disease (2016 Science Direct). “We hypothesize that sleep and circadian disruption in humans alters the gut microbiota, contributing to an inflammatory state and metabolic disease associated with shift work.” 

Missing the Dark: Health Effects of Light Pollution (2009 Environmental Health Perspectives). “A team of Vanderbilt University researchers considered the possibility that constant artificial light exposure in neonatal intensive care units could impair the developing circadian rhythm of premature babies… The researchers concluded that excessive artificial light exposure early in life might contribute to an increased risk of depression and other mood disorders in humans.” 

Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness (2015 National Academy of Sciences). “Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness than when reading a printed book.” 

Sleep, Appetite, and Obesity—What Is the Link? (2004 PLOS Medicine). “A recent prospective study found an association between sleep curtailment and future weight gain. The mechanism linking short sleep with weight gain is unknown, but Mignot and colleagues’ study in this month’s PLoS Medicine adds to the growing evidence implicating leptin and ghrelin, the two key opposing hormones involved in appetite regulation.” 

Consequences of Artificial Light at Night: The Linkage between Chasing Darkness Away and Epigenetic Modifications (2019 Intechopen.com). “Currently, it is clear that electric light not only has remarkable anthropological advantages, but also severe adverse ecological and public health concerns. One of the most alerting impacts of ALAN on public health is the potential association between SWL exposure and cancer development, particularly in urbanized regions worldwide.  …The accumulating data regarding the adverse effects of light pollution on ecology and heath compel us to take drastic and rapid measures to reduce light pollution by extreme regulation or at least reducing SWL emission by developing safe lightning technology.” 

Acute dim light at night increases body mass, alters metabolism, and shifts core body temperature circadian rhythms (2014 Chronobiology International). “The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) (∼5 lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. … We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain.” 

Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption (2017 Science Direct). “Exposure to Artificial Light At Night (ALAN) results in a disruption of the circadian system, which is deleterious to health. In industrialized countries, 75% of the total workforce is estimated to have been involved in shift work and night work. Epidemiologic studies, mainly of nurses, have revealed an association between sustained night work and a 50–100% higher incidence of breast cancer. The potential and multifactorial mechanisms of the effects include the suppression of melatonin secretion by ALAN, sleep deprivation, and circadian disruption.” 

Physiological responses to daily light exposure (2016 Nature). “It has been reported that daily melatonin administration suppressed abdominal fat deposition and plasma leptin levels. Blunted nighttime melatonin rhythms caused by daily long-term light have been shown to increase visceral adiposity in rats. Furthermore, melatonin influences clock gene expression in peripheral tissues such as the heart and similarly may modulate clock gene expression in the peripheral tissue involved in metabolism. These studies may explain the greater extent of abdominal adipose deposition observed in birds raised with daily long-term light periods in this study.” 

Constant light alters serum hormone levels related to thyroid function in male CD-1 mice (2018 Chronobiology International). “Mice were exposed to LL [continuous light] or a 12:12 Light:Dark (LD) cycle for 6 weeks; then glucose tolerance and thyroid hormone levels were measured at ZT 6 and ZT 18. There was day/night variation in glucose tolerance, but LL had no effect. LL reduced TSH, increased fT4, and abolished day/night variation in fT3 and leptin. These findings illustrate that LL alters thyroid-related hormones, providing evidence of a link between circadian disruption and thyroid function.”

The Cost of Activity during the Rest Phase: Animal Models and Theoretical Perspectives (2018 Frontiers in Endocrinology). “…Many young adults shift their activity phase and display what is known as “eveningness,” which involves being active during a large proportion of the night. There is compelling evidence that in humans, voluntary shifts to a nocturnal activity profile result in substantial negative outcomes, including eating disorders (22), diabetes, and metabolic syndrome (23). Further, eating at the inappropriate phase has been linked to obesity in humans and animals (24, 25). These problems have clear negative impacts on the human capital of society.” 

Hormonally mediated effects of artificial light at night on behavior and fitness: linking endocrine mechanisms with function (2018 Journal of Experimental Biology). “To conclude, in this Review we have highlighted several endocrine pathways that are affected by ALAN. As ALAN is increasingly recognized as a threat to biodiversity and ecosystem services, there is considerable interest in reducing its impact via informed policy decisions (Hölker et al., 2010; Knop et al., 2017). …Before development plans begin for new urban areas, which are projected to increase by 50% by 2025 (United Nations, 2014), we should be assessing and implementing alternative lighting regimes (Gaston et al., 2012), in complement with consideration of other factors within an urban environment, such as temperature, noise or pollutants (Swaddle et al., 2015). In fact, ‘orange’ lighting with decreases in the blue spectrum range may be more aesthetically pleasing for humans as well as able to limit physiological costs (Figueiro et al., 2011; Heo et al., 2017). Therefore, we should be looking into alternatives to broad-spectrum intense lighting sources and advocate for these alternatives to improve the health and productivity of organisms that depend on daily and seasonal light–dark cycles.”

Evening light exposure to computer screens disrupts human sleep, biological rhythms, and attention abilities (2017 Chronobiology International ). “Irrespective of light intensity, SWL illumination significantly disrupted sleep continuity and architecture and led to greater self-reported daytime sleepiness. SWL light also altered biological rhythms, subduing the normal nocturnal decline in body temperature and dampening nocturnal melatonin secretion. Light intensity seemed to independently affect sleep as well, but to a lesser degree. Both light intensity and wavelength negatively affected morning attention. In sum, light wavelength seems to have a greater influence than light intensity on sleep and a wide-range of biological and behavioral functions.” 

The impact of light from computer monitors on melatonin levels in college students (2011 Biogenic Amines). “Self-luminous electronic devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. … Melatonin concentrations after exposure to the blue-light goggle experimental condition were significantly reduced compared to the dark control and to the computer monitor only conditions. Although not statistically significant, the mean melatonin concentration after exposure to the computer monitor only was reduced slightly relative to the dark control condition.” 

Light attenuation by the human eyelid (1996 Science Direct). “Although it has been reported that light treatment during sleep can modify biological rhythms, the amount of light that is transmitted through the human eyelid has not been established. We evaluated eyelid transmission with a visual threshold response. Estimated light transmission through the eyelids was 0.3% for blue, 0.3% for green, and 5.6% for red light.” 

Pulsing blue light through closed eyelids: effects on acute melatonin suppression and phase shifting of dim light melatonin onset (2014 Nat Sci Sleep). “Reported here are the results of two studies investigating the impact of a train of 480 nm (blue) light pulses presented to the retina through closed eyelids on melatonin suppression (laboratory study) and on delaying circadian phase (field study). Both studies employed a sleep mask that provided narrowband blue light pulses of 2-second duration every 30 seconds from arrays of light-emitting diodes. The results of the laboratory study demonstrated that the blue light pulses significantly suppressed melatonin by an amount similar to that previously shown in the same protocol at half the frequency (ie, one 2-second pulse every minute for 1 hour).” 

A train of blue light pulses delivered through closed eyelids suppresses melatonin and phase shifts the human circadian system (2013 Nat Sci Sleep). “The results of this study further our basic understanding of circadian phototransduction and broaden the technical foundations for delivering light through closed eyelids during sleep for treating circadian sleep disorders.” 

Evaluating Potential Spectral Impacts of Various Artificial Lights on Melatonin Suppression, Photosynthesis, and Star Visibility (2013 PLOS One). “Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered… Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech’s Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps.” 

Limiting the impact of light pollution on human health, environment and stellar visibility (2011 Science Direct). “…Even after the best control of the light distribution is reached and when the proper quantity of light is used, some upward light emission remains, due to reflections from the lit surfaces and atmospheric scatter. The environmental impact of this “residual light pollution”, cannot be neglected and should be limited too. … Migration from the now widely used sodium lamps to white lamps (MH and LEDs) would produce an increase of pollution in the scotopic and melatonin suppression bands of more than five times the present levels, supposing the same photopic installed flux. This increase will exacerbate known and possible unknown effects of light pollution on human health, environment and on visual perception of the Universe by humans.” 

Night light intensity and women’s body weight: Evidence from Nigeria (2018 Science Direct). “Higher stages of nightlight intensities are associated with higher rates of overweight and obesity.” 

Dark matters: effects of light at night on metabolism (2018 Proceedings of the Nutrition Society). “…Light at night can derange temporal adaptations. Indeed, disruption of naturally evolved light–dark cycles results in several physiological and behavioural changes with potentially serious implications for physiology, behaviour and mood. Night-shift workers are predisposed to obesity and dysregulated metabolism that may result from disrupted circadian rhythms.” 

Light at night, clocks and health: from humans to wild organisms (2016 Royal Society Biology Letters). “Many different non-visual responses, including circadian responses, have different spectral sensitivity, peaking at short wavelengths between 450 and 490 nm [1]. The recent shift from sodium lamps (approx. 589 nm) to fluorescent and LED lights of considerably shorter wavelengths has highlighted the need to trade-off economic and health benefits, as the latter types are increasingly used both indoors and outdoors.” 

The dark side of light at night: physiological, epidemiological, and ecological consequences (2007 Journal of Pineal Research). “Should exposure to light be regulated as endocrine disrupting compounds in the environment? Proposals have been put forth to decrease levels of urban sky glow through light shields, reduction in the number of lights, as well as through an adjustment of the color spectrum produced by external lighting towards low‐level red lighting and away from the highly disruptive high‐energy blue lighting. It is clear that increasing levels of urban sky glow can have serious medical and ecological repercussions.” 

Using light to reset the body clock can treat brain disorders (2017 New Scientist). “I think we’re going to see a complete revolution in lighting and architecture in a very short space of time.”

Mitochondrial signal transduction in accelerated wound and retinal healing by near-infrared light therapy (2004 Mitochondrion). “Photobiomodulation by light in the red to near infrared range (630-1000 nm) using low energy lasers or light-emitting diode (LED) arrays has been shown to accelerate wound healing, improve recovery from ischemic injury in the heart and attenuate degeneration in the injured optic nerve.” 

Tunable LED lighting promises to reduce the incidence of myopia (2019 LEDs Magazine). “Long hours of indoor study and the lack of exposure to daylight is causing a myopia epidemic in young people around the globe…” 

Disruption of Circadian Rhythms by Light During Day and Night (2017 Curr Sleep Med Rep.). “To understand the health effects of light-induced circadian disruption, we need to measure and control light stimulus during the day and at night.” 

Blue light has a dark side (2012) 

Electric light, particularly at night disrupts human circadian rhythmicity: is that a problem? (2015 Royal SocietyPublishing) 

Lighting for the human circadian clock: recent research indicates that lighting has become a public health issue (2004 Science Direct). “Constant light suppressed MLT, increased cancer cell growth rates, and increased LA uptake into cancer cells. The opposite was seen in the light–dark group. The proposed mechanism is the suppression of nocturnal MLT [melatonin] by exposure to LAN [light at night] and subsequent lack of protection by MLT on cancer cell receptor sites which allows the uptake of LA [linoleic acid] which in turn enhances the growth of cancer cells.” 

Chronobioengineering indoor lighting to enhance facilities for ageing and Alzheimer’s disorder (2013 Intelligent Buildings International). “Modern lighting systems have traditionally focused on providing sufficient illumination for people to navigate and manipulate their environments without regard to the side effects that lighting might have on temporal aspects of behaviour and physiology. However, studies involving shift work and other applications of artificial lighting have indicated that these side effects can be quite significant. Furthermore, when an ageing circadian system is coupled with a deteriorating physiology, the side effects of a 24/7 artificially illuminated indoor environment can be especially debilitating, especially for older adults with dementia.” 

First do no harm (2014 LEDs Magazine). “Both the scientific and medical community are now coming to realize that a potential problem arises when circadian-naïve design professionals are unintentionally setting into motion the very basis for circadian desynchronization by blindly specifying blue-weighted white light for most projects irrespective of biologically appropriate seasonality, circadian-correct time of day or night, or even under certain conditions contraindicated for specific age groups.” 

Outdoor Artificial Nighttime Light and Use of Hypnotic Medications in Older Adults: A Population-Based Cohort Study (2018 Journal of Clinical Sleep Medicine). “Outdoor artificial nighttime light exposure was significantly associated with prescription of hypnotic drugs in older adults. These findings are consistent with the hypothesis that outdoor artificial nighttime light may cause sleep disturbances.” 

Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study) (2018). “Both prostate and breast cancer were associated with high estimated exposure to outdoor ALAN in the blue-enriched light spectrum.” 

Light pollution: the possible consequences of excessive illumination on retina (2016 PubMed.gov) “Although, the consequences of unnatural illumination or light pollution have been underestimated by modern society in its way of life, light pollution may have a strong impact on people’s health. The effects of artificial light sources could have direct consequences on retinal health. Constant exposure to different wavelengths and intensities of light promoted by light pollution may produce retinal degeneration as a consequence of photoreceptor or retinal pigment epithelium cells death.” 

WVU researchers identify how light at night may harm outcomes in cardiac patients (2019 mybuckhannon.com). “In a study funded by the National Institutes of Health, West Virginia University neuroscientists linked white light at night—the kind that typically illuminates hospital rooms—to inflammation, brain-cell death and higher mortality risk in cardiac patients.” 

Smartphones Ruin More Than Your Sleep — They May Also Be Destroying Your Vision (2014 Business Insider). “Our various personal electronic devices emit blue light because it’s so bright. That’s the only way we can see those screens when the sun is shining. But we’ve started to have regular close-up nighttime exposure to this light only in the past 10 or 20 years…” 

What is the blue light from our screens really doing to our eyes? (2014 GIGAOM). “An eye doctor says he’s recently seen a few 35-year-old patients whose lenses, which are typically clear all the way up until around age 40, are so cloudy they resemble 75-year-olds’. A sleep doctor says kids as young as toddlers are suffering from chronic insomnia, which in turn affects their behavior and performance at school and daycare. A scientist finds that women who work night shifts are twice as likely to develop breast cancer than those who sleep at night. What do all these anecdotes have in common? Nighttime exposure to the blue light emanating from our screens.” 

The Effects of Blue Light on Ocular Health (2000 Texas School for the Blind). “There is mounting medical evidence that prolonged exposure to blue light may permanently damage the eyes, contribute to the formation of cataracts and to the destruction of cells in the center of the retina… Ham et al. (1980) and Gorgels and van Norren (1995) pointed out that actinic, or photochemical damage to retinal tissue, is more a function of wavelength than either intensity or duration. Gorgels and van Norren, after examining rat retinas damaged by blue light, wrote “duration had no influence on damage threshold dose, nor on morphology. We conclude that wavelength (and neither irradiance nor duration) is the factor responsible for the encountered morphological differences”(p.859).” 

Removal of the blue component of light significantly decreases retinal damage after high intensity exposure (2018 PLOS One) 

Effects of the Emitted Light Spectrum of Liquid Crystal Displays on Light-Induced Retinal Photoreceptor Cell Damage (2019 Journal of Molecular Sciences). “LEDs emit higher levels of blue light with shorter wavelengths than conventional light sources and are accompanied by an enhanced risk of photo-injury. Extensive blue light exposure also disrupts circadian rhythms, which may constitute a health hazard for humans. For example, nighttime lighting with blue light and the desynchronization of circadian rhythms may increase the incidences of psychiatric disorders, diabetes, obesity, and several kinds of cancers… As consumer electronics are indispensable in daily life in the modern era of computing, the quest for increased image quality may be accompanied by higher energy emission of the light source, in turn resulting in more severe damage to the retina and enhancement of other blue light hazards such as circadian rhythm desynchronization. This represents a major societal health concern toward which traditional blue light filters and blocking lenses may be poorly suited, as consumers may be unwilling to sacrifice visual quality.” 

Is Blue Light Good, Bad or In-between? (2018 SageGlass). “Blue light is said to have both harmful and beneficial effects on health, and these effects depend on the time, duration and intensity of a person’s exposure to it. It is also worth noting that the effects on humans differ depending on the type of blue light: Blue-violet light is responsible for the photochemical effects on the retina, while blue-turquoise light affects the body clock.” 

The impact of daytime light exposures on sleep and mood in office workers (2017 Sleep Health Journal) “Compared to office workers receiving low levels of circadian-effective light in the morning, receiving high levels in the morning is associated with reduced sleep onset latency (especially in winter), increased phasor magnitudes (a measure of circadian entrainment), and increased sleep quality. High levels of circadian-effective light during the entire day are also associated with increased phasor magnitudes, reduced depression, and increased sleep quality.” 

Circadian photoreception: ageing and the eye’s important role in systemic health [excellent References section!] (2008 British Journal of Ophthalmology). “Ageing increases crystalline lens light absorption and decreases pupil area resulting in progressive loss of circadian photoreception. A 10-year-old child has circadian photoreception 10-fold greater than a 95-year-old phakic adult. A 45-year-old adult retains only half the circadian photoreception of early youth. Pseudophakia improves circadian photoreception at all ages, particularly with UV-only blocking IOLs which transmit blue wavelengths optimal for non-visual photoreception.” 

Less Exposure to Daily Ambient Light in Winter Increases Sensitivity of Melatonin to Light Suppression (2006 Journal
Chronobiology International). “The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6±18.4%) than summer (37.2±33.2%), p<0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter. The results suggest that the increase in suppression of melatonin by light in winter is caused by less exposure to daily ambient light.” 

Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases (2015 Journal Chronobiology International). “Living organisms, including humanoids, are genetically adapted to the natural environment experienced by their ancestors during evolution. This environment is defined by sunlight during the day alternating with darkness, except for the dim illumination of stars, planets, and moon, during the nighttime… The environment of today is far different than that experienced during evolution; in most parts of the world artificial light has replaced natural sunlight during the day and ALAN has replaced darkness during the night. Moreover, polluted skies and dense residential housing of cities reduce the amount of daytime UV-B irradiation reaching the earth’s surface thereby further contributing to the risk for vitamin D deficiency.” 

Night work and miscarriage: a Danish nationwide register-based cohort study (2018 Occupational and Environmental Medicine). “Women who had two or more night shifts the previous week had an increased risk of miscarriage after pregnancy week 8 (HR 1.32 (95% CI 1.07 to 1.62) compared with women, who did not work night shifts. The cumulated number of night shifts during pregnancy weeks 3–21 increased the risk of miscarriages in a dose-dependent pattern. The study corroborates earlier findings that night work during pregnancy may confer an increased risk of miscarriage and indicates a lowest observed threshold level of two night shifts per week.” 

Night Shifts, Long Hours Linked to Miscarriages and Preterm Births (2019). “Pregnant women who work nights or long hours may be more likely to have a miscarriage or preterm delivery than mothers with day jobs, a research review suggests. With night shifts, pregnant women were 21% more likely to have preterm deliveries and 23% more likely to have miscarriages than women who worked days, the analysis found.” (https://www.medscape.com/viewarticle/915808)

Sleeping with artificial light at night associated with weight gain in women (2019 National Institute of Environmental Health Sciences). “The results varied with the level of artificial light at night exposure. For example, using a small nightlight was not associated with weight gain, whereas women who slept with a light or television on were 17% more likely to have gained 5 kilograms, approximately 11 pounds, or more over the follow-up period. The association with having light coming from outside the room was more modest… Their findings did not change when analyses controlled for characteristics that may be associated with exposure to light at night. These factors included age, having an older spouse or children in the home, race, socioeconomic status, calories consumed, and physical activity.” 

Being Exposed to Even a Small Amount of Light During Sleep is Linked to Depression (2018 Time). “People who saw more than five lux of light at night were much more likely to develop symptoms of depression than those who slept in a completely dark room. (For context, 10 lux is like looking at a candle from about a foot away.) The study did not determine how long someone would need to be exposed to nocturnal light to see these effects, but a prior study in hamsters placed the threshold at four weeks of five-lux exposure. 

Indoor light pollution and progression of carotid atherosclerosis: A longitudinal study of the HEIJO-KYO cohort (2019 Science Direct). “In conclusion, we found a clear and significant association between bedroom LAN intensity and progression of subclinical carotid atherosclerosis, which was independent of known risk factors for atherosclerosis, including age, obesity, smoking, economic status, hypertension, and diabetes.” 

Effects of LED streetlights on autistic son led Damien McNamara on dark sky campaign (2019 Stuff.co.nz) 

Research on retina damage sparks fresh LED health scare (2013 LUX Magazine) Dr. Celia Sanchez Ramos of Complutense University, who has been investigating what’s known as the ‘blue light hazard’, predicted ‘an epidemic’ of retina problems due to increased exposure to LED lighting.

Research Confirms that Light Pollution Can Suppress Melatonin Production in Humans and Animals (2019 LED Magazine) “At high light levels, melatonin production is suppressed. In darkness, melatonin is produced. The sensitivity threshold for humans is 6 lux – street lighting is typically higher. …Even very low illuminance levels can suppress melatonin production for some vertebrate classes: in fish the threshold is 0.01 lux, in rodents 0.03 lux and in sensitive humans 6 lux; pure blue light showed much lower thresholds. For comparison, the illuminance levels at night: on a starry night, the illuminance is 0.001 lux. On a full-moon night it reaches a maximum of 0.3 lux. The skyglow of a city, a form of light pollution, can reach illuminances of up to 0.1 lux, and outdoor lighting on the order of 150 lux.”

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates (2019 Sustainability) “Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels.”

Measuring and using light in the melanopsin age (2014 Trends in Neurosciences) “If the broad objective is to minimize the activation of ipRGC outputs, the goal should be to keep retinal irradiance as low as possible. There is no established threshold below which these systems are completely blind to light, so total darkness during sleep may be ideal where practical. Likewise, with respect to the visible spectrum, any wavelength can, in principle, activate the system. However, given that the relative sensitivity of these non-visual responses is generally reduced in the longer visible wavelength range [i.e., amber], light sources should be biased towards longer visible wavelengths, to the extent consistent with other demands.”

Dark sky tourism: economic impacts on the Colorado Plateau Economy, USA (2019). “The authors find that non-local tourists who value dark skies will spend $5.8bn over the next 10 years in the Colorado Plateau. These tourist expenditures will generate $2.4bn in higher wages and create over 10,000 additional jobs each year for the region. Furthermore, as dark skies are even more intense natural amenity in the non-summer months, they have the ability to increase visitor counts to national parks year-round and lead to a more efficient use of local community and tourism-related resources throughout the year.” 

Dark Sky Tourism on Rise as More People Seek Out The Stars (2011). “Why wax on about this? Because until I experienced someplace with a truly dark sky–defined by the Royal Observatory’s Dan Hillier as “when you can see the Milky Way”–I had really didn’t know what I was missing. And what I was missing seemed nearly immediately to be an essential part of the human experience.”

Stargazing and dark sky tourism (2011). “Through 2010, we have seen a jump in the business by 25 to 30%, specifically because of the Dark Sky Park.” 

Astronomical Tourism: An Often Overlooked Sustainable Tourism Segment (2011). “Astronomy-related visitors relative to overnight park visitors averaged 9.91%. During the peak and shoulder seasons, monthly ASDP visitors comprised 8.1 to 11.8 percent of overnight park visitors. Visitor participation in the ADSP may not seem large in comparison to park recreational visitors. This was due to the large number of visitor arrivals by tour bus (14 % on average) and some visitors by automobile, whose travel often did not include an overnight stay at Bryce Canyon.” 

Travel Trend: Astro-Tourism (2017). “Professionals see Astro-tourism as a critical part of sustainable development for the future of tourism. Several tourism experts are starting to take note of the growing interest and Airbnb even flagged the activity as the next big trend in tourism.” 

To wish upon a star: Exploring Astro Tourism as vehicle for sustainable rural development (2019). “The paper describes how a unique experience such as Astro Tourism can be regarded as viable mechanism to bring about sustainable development in a rural context.” 

The Great Western Starry Way (Glacier to Grand Canyon & beyond) 

Astrotourism is Looking Up (undated). “According to a 2007 study, astrotourism contributes more than $250 million annually to Tucson’s economy.” 

Unique view on a multi-million dollar astro-tourism attraction (2019) 

Destination Darkness (2014) 

The Economics of Dark Skies (2018). “In a recent study… more than 50% of the visitors they surveyed across four National Parks expressed a willingness to pay something to preserve dark skies in the respective surrounding regions. In a separate study, the same authors projected that visitors to national parks in the Dark Sky Cooperative would spend roughly $2.5 billion over the next 10 years, which would lead to 52,000 jobs and $1.1 billion in wages. Several major travel companies and resort destination companies are taking note and now offer star gazing and nighttime activities in their trip packages. While some may disagree with the approach, the monetization of our dark skies, perhaps, will increase our ability to protect them!” 

Smokey Jack Observatory Brings Boom in Tourism to Custer County (2018) “This boom in tourism has also benefited the local B&B operators in the County and contributed to our lodging tax.  Charley Ellison, the owner of Dark Skies Vacations, manages multiple Airbnb properties in the County and reports a strong uptick in bookings this summer, with close to 100% occupancy, due to our Dark Sky Certification. He states that two-thirds of his guests tell him that visiting the SJO and seeing our night sky are primary reasons for visiting the Valley. These out-of-town visitors commonly state how happy they are to learn about our community and how excited they are for a return. Local merchants are also seeing the benefit of the SJO and tourism with the sales of Dark Skies branded apparel and the growing work of local artisans making dark skies related arts and crafts.” 

Announcing Dark Skies: A Practical Guide to Astrotourism (2019)  

 Night Skies Continue to Spark a Creative Light (2019)

Space Tourism Guide (undated) 

Reclaiming the Stars: Justina Parsons-Bernstein and the Utah State Parks dark sky initiative (2017). “If people can’t see the stars, they will go and find them,” Parsons-Bernstein says. “These astro-tourists are coming to Utah from all over the world, because they want to be out in the pristine darkness and see the Milky Way for themselves.”  

Central Oregon Destination Dark Sky Photographers (2019) 

Heavens above (2019). The Mackenzie Basin gets about 150,000 astro-tourists each year, mostly from overseas. “That’s hundreds every day. Since we created our dark sky reserve in 2012, there’s probably been a million visitors, particularly from China, Japan and Korea. “Dark-sky tourism in the Mackenzie is now one of New Zealand’s biggest tourism attractions.” Astro-tourism encourages people to stay longer, because they cannot see all the sights during daylight hours. “If you look at the bed nights in the Mackenzie … it’s about one million bed nights a year. “So big is the impact that Tekapo can hardly cope. Two new hotels are about to be built.” 

A Colorado Town Goes Dark To Let The Milky Way Shine Bright | TODAY (2016)

Mackenzie hopes to lead New Zealand to world dark sky status (2019). “Our night sky is a massive natural asset,” Odey said. “There are opportunities to connect with our neighbouring council in the Mackenzie. Geraldine is  the gateway for a lot of tourism on the way to Aoraki/Mt Cook, and it would make sense for that town to get involved,” Odey said. “When you look at some of the analytics, more than 60 per cent of tourists come to the Mackenzie because of their brilliant night sky.” 

Twinkle, Twinkle: Why Stargazing & Astrotourism Are Reaching New Heights (undated) 

Gazette opinion: Marketing Eastern Montana vacations (2019) 

A decade of the UK’s first Dark Sky Park in Galloway (2019). “Dark sky tourism and astro tourism are now firmly embedded within several regions of Scotland attracting visitors out of season, boosting visitor income and occupancy rates for accommodation providers,” she said. Ms Ward said it was estimated the park generated about £500,000 a year from tourism… “Dark sky tourism has been of tremendous benefit to many businesses in the local area, particularly accommodation providers – many of whom report being as busy in winter as they are in summer.” 

Stargazing and dark sky tourism (2011). “There has to be more to the location. But a dark sky can be used as an asset just like beautiful scenery,” says Mr Alexande. Stargazers need food, water, a bed for the night and toilet facilities. For this reason, national parks, with their established visitor facilities, are starting to make a virtue of their own dark skies. 

Welsh skies dazzle in new ‘astro-tourism’ trail (2019) 

CTO grants Dark Sky Tour of Colorado $25,000 (2019)

Town looks toward dark skies (2019) “This is where the West still lives. Why not have the night sky of the West still live as the cowboys saw it 100, 150 years ago?”

ALAN 2018 Conference Abstracts (very large PDF file)

Consequences of Artificial Light at Night: The Linkage between Chasing Darkness Away and Epigenetic Modifications (2019). “Currently, it is clear that electric light not only has remarkable anthropological advantages, but also severe adverse ecological and public health concerns. One of the most alerting impacts of ALAN on public health is the potential association between SWL exposure and cancer development, particularly in urbanized regions worldwide.  …The accumulating data regarding the adverse effects of light pollution on ecology and heath compel us to take drastic and rapid measures to reduce light pollution by extreme regulation or at least reducing SWL emission by developing safe lightning technology.” 

Fighting Light Pollution: Smart Lighting Solutions for Individuals and Communities  (2012) (e-book)

Light Pollution as a New Risk Factor for Human Breast and Prostate Cancers (2013). Abraham Haim, Boris A. Portnov. 

The End of Night by Paul Bogard (2013) (excellent interview linked here!)

Light Pollution A Global Discussion (2018)

 

 

 

 

Smart Outdoor Lighting Alliance (excellent site!)

ALAN [Artificial Light at Night, includes archived paper abstracts] 

Blanco County [Texas] Friends of the Night Sky

Carpe Noctem [from Serbia!] 

Colorado Plateau Dark Sky Cooperative 

Dark Skies of the Wet Mountain Valley (Colorado) 

Dark Sky Guides (Waterton-Glacier DSP) 

Dark Sky Missouri 

Flagstaff Dark Skies Coalition [excellent site!]Globe at Night 

Headlands [Michigan] International Dark Sky Park 

IDA Texas 

Jasper Dark Sky Festival (Alberta, October 15-25, 2020)

Light Pollution Science and Technology Institute 

Loss of the Night citizen science project 

Natural Sounds and Night Skies Division, U.S. National Park Service 

Night Sky Network

Ogden Valley [UT] Starry Nights 

Royal Astronomical Society of Canada 

Santa Cruz Chapter of the IDA 

Soft Light Houston (excellent gallery with photo examples!) 

The Commission for Dark Skies [England] 

The Consortium for Dark Sky Studies [University of Utah] 

The Night Skies of the U.S. National Park Service 

Waterton-Glacier International Peace Park (Canada/U.S.) 

Waterton Glacier International Dark Sky Park 2017-2018 Annual Report 

Wyoming Stargazing 

 

Blue Marble (interactive night view of Earth, uses 2012 VIIRS data)

Dark Sky Meter

Dark Site Finder 

Dark Sky Maps (weather forecasts including cloud cover forecast, not light pollution!)

Light Pollution Atlas 2006 

Light Pollution Map (excellent!)

Night Sky Monitoring Database (Google Earth layers) 

Radiance Light Trends (If you want to analyze of radiance VIIRS/DMSP changes over a period of time) 

Skyglow Estimation Toolbox (requires advanced computer skills) 

The new world atlas of artificial night sky brightness (2016).  “This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.” 

The New World Atlas of Artificial Sky Brightness (the actual map)

World Atlas Night Sky Brightness 

Cine Meter II ($25, for iPhones) 

Lumu Light Meter (free/$299 upgrade, for iPhones) 

Dark Sky Map (free) 

f.lux (Removes blue light from cell phone at night!) 

Night Shift (blue light filter for Apple products) 

Does Apple’s “Night Shift” Really Work? (2018 SleepBetter.org). “What they found was that melatonin was decreased under all of the conditions.  Subjects who used the iPad on regular settings (without Night Shift) had their melatonin levels reduced by 23%.  Those who used Night Shift with their screen brightness at a standard level had their melatonin reduced by 19%.  A group that used Night Shift and reduced brightness, however, saw melatonin reduced by only 12%. So, what’s the takeaway?  Truly, even reducing melatonin levels by 12% could be enough to disrupt your body’s ability to easily fall asleep.  But, if you must use your screens at night, you should not only use a feature like Night Shift, but also turn down the brightness of your device.” 

Nurus Light Wellness (Kelvin and lux meter) 

White Balance Color Temp Meter (Kelvin meter, 99 cents) 

LightSpectrumPro EVO ($1.49 Kelvin meter) 

24 Screen-dimming apps 

10 blue light filters: How to prevent eye strain from computer (excellent explanations!) 

NightCap Camera for iPhone (for photography after dark)

Artificial Light at Night (ALAN) Research Literature Database (2,500+ records!) 

ALAN (Artificial Light At Night, includes archived abstracts)

Radiance Light Trends (If you want to analyze radiance (VIIRS/DMSP) changes over a period of time) 

World Atlas Night Sky Brightness 

Portal to the Heritage of Astronomy (undated). “The [UNESCO] Portal to the Heritage of Astronomy exists to raise awareness of the importance of astronomical heritage worldwide and to facilitate efforts to identify, protect and preserve such heritage for the benefit of humankind, both now and in the future.” 

U.S. Federal Science records for light pollution (2019) 

Lighting Research Center, Light and Health (refereed journal articles from 1996-2019) 

Urban Light Lab [Dark Sky] Publications (1993-2019) 

SlidePlayer: Light Pollution at Night (dozens of online slide presentations!) 

Project aims to document dark skies and light pollution in Missouri (2019). “”We want to get a baseline of where we are right now with some actual scientific measurements. And, we have some areas in Missouri that are very dark. We want to be able to designate them as dark-sky places.” 

Visible Earth (night lights NASA image collection) 

The problem of light pollution — and 5 ridiculously easy ways to fix it (2019 TED talk)

The Day the Lights Went Out (2013) (wonderful short!) 

How blue light affects us (2018) (excellent 4-minute video!) 

Planning for Success with LED Streetlighting (2019 thorough 58-minute video)

Podcast #312: The Costs of Light Pollution and the Benefits of Darkness (2017) (podcast) 

Light in harmony with human and nature (2018) (LED retrofit done right in small-town Austria!) 

Cave Creek Dark Sky Initiative (2019) 

What is Light Pollution, and How Can You Help Reduce It? (2013) 

Say No to the Glow (2017) 

Maintaining the Dark Skies of Jackson Hole (2014) (excellent talk!) 

The Night Sky Threatened (2015) (from Theodore Roosevelt National Park) 

Biological Background, Photometric Assessment and Transfer to Application (2013) (technical but thorough)

Restoring the night sky for a healthier future (2014) 

Reclaiming the Night (series of interviews and videos, unfortunately the documentary hasn’t been completed) 

Colorado Plateau Urban Development (2017) 

The Towns That Embraced Darkness to See Starlight (2016) 

Remaining Challenges: LED Street Lighting (2015) (audio only) 

City of Tucson Upgrades Streets to Networked LED System (2017) 

Light Pollution Is More Dangerous Than You Think! (2016) 

Light increases crime, says student (2014) 

Light Pollution 101 (undated) 

Lost in Light (2016) 

Subaru Outback Dark Sky (2016 commercial) 

Why We Need Darkness by Paul Bogard (2016 TED talk) 

Maglite Demo: Lessen Light Pollution by Shielding 

Cree LED Lighting (2017) 

De-Light the Night (Light Pollution Solutions) (2015) (TEDx talk by Diane Turnshek) 

Circadian Rhythm Lighting on Aarhus University Hospital (2015) 

How do you feel under a canopy of stars? (2019) 

Light Pollution – The Disappearing Darkness (2017) 

Springfield Goes Dark 

Light Pollution – The Effects on Animals and Humans (webinar) 

Light health and human wellbeing (2012 webinar) 

LED Lights: The Dark Side (2018) (CBS News) 

Why an enlightened design integrates illumination (2015) 

Starry Nights (from Subaru) 

Fox Fires (inspired by the Finnish folk tale of the aurora borealis)

How one NASA image tells dozens of stories (2019) 

PEAK ENVIRONMENT: 44 THE WONDER OF DARK SKIES (2019 podcast) 

Mexico : ‘Dark-sky friendly’ streetlights to reduce light pollution (2017) 

Time to Protect the Night (2018) 

Why We Are Losing the Night Sky (2019) 

Light Pollution and Animals (2016)

 Does light pollution affects birds? (2013)

When is Milky Way Season? (2019) 

Every Visible Star in the Night Sky, in One Map (2019) 

Everything You Ever Wanted to Know About Light Pollution (2006) 

Dark Skies Rangers: Dark Skies and Energy Education (undated)

Quality Lighting Teaching Kit (undated)

Education & Public Engagement (undated) 

Teachers Preferred Natural Daylight Inside PA Elementary School (undated, Eneref Institute)

Thinking Inside the Box [About Skyglow, Tresspass, Glare] (2007, unknown magazine)

How to Prepare an Interpretive Program (undated) 

Outreach Training (2018 free training videos!) 

Junior Ranger Night Explorers (2019 National Park Service)

History of the Telescope (undated)

Paper Plate Education (undated, two simple light shielding demonstrations) 

Let There Be Night science experiment (2009 school student light pollution experiment using Legos) 

Light Fast (undated, NightWise.org) (>100 ideas for using less light) 

Lesson Plan for Nighttime Poetry (undated) 

 

 

 

 

 

BUG Rating System & Nighttime LED Lighting (2019). “What is a BUG Rating? The BUG lighting classification system is a useful measurement of nighttime luminaire performance. The system was developed by the Illuminating Engineering Society (IES) and the International Dark Sky Association as a way of evaluating any outdoor light fixture. It was first added to the Luminaire Classification System (LCS) in 2009, replacing the previous system that was mainly geared toward street lights. In the case of these ratings, the word “BUG” is an acronym for Backlight, Uplight and Glare. All three are forms of stray light that can be emitted from a fixture. Although each does have positive uses in certain applications, they are generally considered “bad” light, as they often are not light you can practically use. But each is noticeably worse for some tasks than others, and the BUG rating helps to quantify this.” 

Understanding the Bortle Scale 

Sky Quality Meter 

Rate Your Skyglow (2008). “This piece describes the technical details of how to measure and describe skyglow using the World Atlas of Artificial Night Sky Brightness and the Sky Quality Meter.” 

How To Conduct A Sky Quality Survey 

Using Sky Quality Meters to Measure Sky Brightness 

Street and Parking Facility Lighting Retrofit Financial Analysis Tool (2017) 

Toolkit: Outdoor Lighting (2016)

Bright Idea: Lighting Toolkit for K-12 School Districts (2018) 

SQM Connected Program (datalogging sky quality meters) 

Stability of the Nine Sky Quality Meters in the Dutch Night Sky Brightness Monitoring Network (2015) 

How to Never Miss an Aurora (2014) 

 

Human Centric Lighting – The New X Factor? (2018 Lighting in Architecture) “…We’ve grossly underestimated the powerful influence of light on biology and therefore incorrectly assumed lighting plays a minor role in health and wellbeing. Now we know the opposite is true, we need to be more resourceful in our research because medical ethics prevents direct study on humans. We do know from numerous research on test animals and the information obtained, that artificial light at night can have serious negative effects including alterations to the circadian clock [3], patterns of behaviour [4], or biochemistry [5], as well as an increase in various diseases [6].” 

Will tunable street light breakthrough silence LED critics? (2016 LUX Magazine)

LED Color-Tunable Products (undated, Energy.gov) (field evaluations in classrooms, hospital, senior care facilities!) 

Webinar: Tuning the Light in Senior Care (2016 Energy.gov) 

Tuning Hospital Lighting (2017 Energy.gov) 

Tuning the Light in Classrooms (2017 Energy.gov) 

Soraa’s violet LEDs can help you sleep better with healthy lights (2018 VentureBeat.com)

Implementing human-centric lighting (2018 EDN.com)

WHC [Fire Department] Installs State-of-the-Art Circadian LED Lighting System – Fatigue Management (2019 Coatesville Fire Dept.)

Tuning the Light in a Senior-Care Facility (2016 Energy.gov) “For the three months following the LED trial installation, target behaviors such as yelling, agitation and crying were reduced by an average of 41 percent for the three residents in the study, relative to the three months immediately preceding the installation.” 

A Dennis-centric reality check on Human-Centric Lighting (2014 EDN.com) 

Human Centric Lighting (2012 HumanCentricLighting.org) 

OLED Basics (undated, Energy.gov)

 

Blackfeet Astronomy (2011 MT Office of Public Instruction) (PDF format)

Blackfeet Astronomy – Montana Skies (2018 MT Office of Public Instruction) (6 videos)

Crow Astronomy (2011 MT Office of Public Instruction) (PDF format)

Crow Astronomy – Montana Skies (2018 MT Office of Public Instruction) (6 videos)

Little Bighorn Battlefield’s Night Sky (2018 Nat. Park Service) 

Indigenous Astronomy: The Blackfoot of The North American Plains (2003 Canadian Heritage Information Network)

BisonSat launched into space (2015 Char-Koosta News). BisonSat, or Nwist Q̓ʷiq̓ʷáy – meaning “Buffalo Up Above” in Salish, will be used for Earth imaging, land classification and studies of clouds. 

“Canadian” Star Chart (2012 Wilderness Astronomy)

Navajo Star Ceilings (undated, UNESCO’s Astronomy and world heritage)

Relearning The Star Stories Of Indigenous Peoples (2019 Science Friday)

Ancient cultures may have used medicine wheel to connect stars, stories, Bozeman researcher says (2019 Billings Gazette)

Portal to the Heritage of Astronomy (undated UNESCO’s Astronomy and world heritage). “The [UNESCO] Portal to the Heritage of Astronomy exists to raise awareness of the importance of astronomical heritage worldwide and to facilitate efforts to identify, protect and preserve such heritage for the benefit of humankind, both now and in the future.” 

World’s First ‘Dark Sky Nation’ (2015 DarkSky.org). As a result of the Kaibab Band of Paiute Indians’ work to protect the pristine night skies over its northern Arizona territory, IDA is pleased to announce the designation of the Kaibab Paiute Indian Reservation as an International Dark Sky Community. The IDA status makes the Kaibab Paiute truly the world’s first ‘dark sky nation.’

Star Stories in Native America (2015 Native America Calling)

  Bat-friendly street lights for Worcestershire crossing (2019 BBC.com). “Research has shown some species of bats avoid areas lit by white lights, which could lead them to use longer and less safe routes.” 

LED lighting could have major impact on wildlife (2017 Physics.org). “Dr Davies added: ‘While these approaches helped to reduce the number of ground dwelling spider and beetle species affected by LED lighting to varying degrees, our study also shows that avoiding these impacts may ultimately require avoiding the use of LEDs and night-time lighting more generally.’” 

High-intensity urban light installation dramatically alters nocturnal bird migration (2017 U.S. National Academy of Science). “Here we report that an iconic urban light installation dramatically altered multiple behaviors of nocturnally migrating birds—but these effects disappeared when lights were extinguished. We recommend selective removal of light pollution during nights with substantial bird migration to mitigate negative effects on birds, in particular collisions with lighted structures.” 

When the sun sets in Las Vegas, grasshoppers swarm the city’s bright lights (2019 television news story) 

Bats avoid flying by streetlight (2009 BBC News). “Scientists have found that, as bats travel to feeding grounds, they avoid hedgerows illuminated by streetlights… These lights mimicked the colour and intensity of ubiquitous sodium streetlights, which are used throughout the world. ’With the lights on, there was about a quarter to an eighth of the activity – or number of bats flying along the route – compared to when the lights were off.’” 

Dutch town goes with bat-friendly streetlights (2018 New Atlas). “Many species of bats have evolved to forage in near-complete darkness, and as a result tend to shy away from white LED and yellowish sodium vapor streetlights. Given that cities are full of these lights, the areas in which the animals can hunt effectively are quite limited. Additionally, the insects that the bats feed upon are attracted to the lights, drawing them into areas where the bats don’t want to go… A year ago, Philips Lighting (now called Signify) announced results of a study which showed that its ClearField red LED lighting didn’t disrupt the behaviour of bats – unlike traditional streetlights. Now, the Dutch town of Zuidhoek-Nieuwkoop has become the first place in the world to use the system.” 

Light pollution hurts urban bats. Trees can help (2019 National Geographic). “Bat activity overall was higher around areas that had lighting and tree cover. But some species reacted differently to the two types of lighting in relation to tree cover, according to the study, published in March in the journal Frontiers in Ecology and Evolution… All bats studied were less active around LED light sources, which attracts fewer insects than UV lights. But high-flying bat species were more active around LED lights within forested areas.” 

How flipping a light switch could save hundreds of seabirds in Bay de Verde (2019 CBC News). “Montevecchi asked the fish plant manager to turn the lights out at night. The manager agreed to darken the plant when there’s no work scheduled. Since then, there have been no reports of dead storm petrels.” 

Chronic exposure to dim artificial light at night decreases fecundity and adult survival in Drosophila melanogaster (2017 PubMed.gov). “Our data highlight that ALAN has the capacity to cause dramatic shifts in multiple life history traits at both the individual and population level. Such shifts are likely to be species-specific, however a more in depth understanding of the broad-scale impact of ALAN and the relevant mechanisms driving biological change is urgently required as we move into an increasing brightly lit future.” 

Artificial light at night alters life history in a nocturnal orb-web spider (2018 PeerJ). “We found that exposure to ALAN accelerated juvenile development, resulting in spiders progressing through fewer moults, and maturing earlier and at a smaller size. There was a significant increase in daily juvenile mortality for spiders reared under 20 lux, but the earlier maturation resulted in a comparable number of 0 lux and 20 lux spiders reaching maturity. Exposure to ALAN also considerably reduced the number of eggs produced by females, largely associated with ALAN-induced reductions in body size.” 

Careful design solutions can ensure that birds maintain a view of the stars during migration (2019 Illuminating Engineering Society). “We are at the onset of light addiction, with LEDs so small they can be put almost anywhere, making once acceptably bright places seem dark again in contrast. While the Model Lighting Ordinance serves as a starting point, it is necessary to continue developing a cohesive model for lighting. As LEDs proliferate, lighting regulation must be developed simultaneously.” 

Animals Need the Dark (2018 U.S. National Park Service) 

Vanishing Sacramento River Salmon – The Threat of Light Pollution (2008 SkyKeepers.org) 

The human-centric focus on the impact of artificial light has overshadowed its effects on animals and plants (2018 SierraClub.org) 

The circadian rhythm of our microbes (2016 EarthSky.org) “As scientists investigate the links between our internal daily patterns, electric light and health, new information about the rhythmicity of our microbiome might hold clues about how this all works together.” 

Artificial light at night as a new threat to pollination (2017 Nature.com). “Here we show that artificial light at night disrupts nocturnal pollination networks and has negative consequences for plant reproductive success. In artificially illuminated plant–pollinator communities, nocturnal visits to plants were reduced by 62% compared to dark areas. Notably, this resulted in an overall 13% reduction in fruit set of a focal plant even though the plant also received numerous visits by diurnal pollinators.” 

Artificial Light is Changing Animal Behavior in Chicago, Study Finds (2019 WTTW/PBS news) 

Nocturnal flight-calling behavior predicts vulnerability to artificial light in migratory birds (2019 The Royal Society) 

Bright lights in the big cities: migratory birds’ exposure to artificial light (2019) (https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/fee.2029)

Naval Station Mayport installs sea turtle-friendly lighting (2019 Ecological Society of America) 

Red light at night: A potentially fatal attraction to migratory bats (2018 Physics.org) 

Nathusius and Soprano bats are attracted to green light (2017) (https://phys.org/news/2017-05-nathusius-soprano-green.html)

New Major Study to Reveal Impacts of Coastal Light Pollution (2018 Environment, Coastal & Offshore Magazine) 

Light pollution increases West Nile virus competence of a ubiquitous passerine reservoir species (2019 Royal Society Publishing). “A simple mathematical modelling exercise indicated that [artificial light at night]-induced increases of host infectious-to-vector period could increase WNV outbreak potential by approximately 41%.”  

Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night (2015 Royal Society Publishing). “Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks.” 

Artificial light at night as a new threat to pollination (2017 Nature.com). “Our findings demonstrate that artificial light at night is a threat to pollination and that the negative effects of artificial light at night on nocturnal pollination are predicted to propagate to the diurnal community, thereby aggravating the decline of the diurnal community.” 

Ecological effects of artificial light at night on wild plants (2016 Journal of Ecology) “In many cases, artificial light in the night-time environment is sufficiently bright to induce a physiological response in plants, affecting their phenology, growth form and resource allocation. The physiology, behaviour and ecology of herbivores and pollinators are also likely to be impacted by artificial light. Thus, understanding the ecological consequences of artificial light at night is critical to determine the full impact of human activity on ecosystems.” 

Cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem (2015 Royal Society Publishing). “These results suggest that physiological effects of light on a plant species within a diverse plant community can have detectable demographic effects on a specialist herbivore.”

Numerical research on the effects the skyglow could have in phytochromes and RQE photoreceptors of plants (2018 Science Direct). “The increase of artificial light at night has a terrible impact on organisms with nightlife patterns such as a migration, nutrition, reproduction and collective interaction. Plants are not free from this issue as they have life cycle events occurring not only yearly but also daily. … In our numerical simulations we found that some lighting systems can have an effect on plant photoreceptors and affect the phenology of plants. Specifically, the lamps that emit the electromagnetic energy in a wide spectral range can have greater effect on the photosensitivity of the plants.” 

Long-term dim light during nighttime changes activity patterns and space use in experimental small mammal populations (2018 Science Direct). “We found that bank voles under ALAN experienced changes in daily activity patterns and space use behavior, measured by automated radiotelemetry. There were no differences in survival and body mass, measured with live trapping, and none in levels of fecal glucocorticoid metabolites. Voles in the ALAN treatment showed higher activity at night during half moon, and had larger day ranges during new moon. Thus, even low levels of light pollution as experienced in remote areas or by sky glow can lead to changes in animal behavior and could have consequences for species interactions.” 

Endogenous cycles, activity patterns and energy expenditure of an intertidal fish is modified by artificial light pollution at night (ALAN) (2019 Science Direct). “Our results indicated that individuals exposed to ALAN exhibited increased oxygen consumption and activity when compared with control animals. Moreover, those fish exposed to ALAN stopped displaying the natural (circatidal and circadian) activity cycles that were observed in control fish throughout the experiment. These changes in physiological function and behaviour could have serious implications for the long-term sustainability of fish populations and indirect impacts on intertidal communities in areas affected by ALAN.” 

Artificial light at night and captivity induces differential effects on leukocyte profile, body condition, and erythrocyte size of a diurnal toad (2018 Wiley Online Library). “We significantly observed higher neutrophil proportions and neutrophils to lymphocytes ratio in toads under constant light treatment. In addition, we observed significantly better body condition and higher erythrocyte size in field toads compared with captive toads. In summary, ALAN can trigger a leukocyte response to stress in males of the diurnal toad M. rubriventris.” 

The impact of artificial light at night on nocturnal insects: A review and synthesis (2018 Wiley Online Library). “Widespread nocturnal artificial illumination radically disrupts the habitats of night‐active species. …The severity of impact will depend on the degree of overlap between the spectral sensitivity of the insect in question and spectral emission (and intensity) of the particular ALAN source (Gaston et al., 2015). Recently, many urban areas have begun to phase out monochromatic long‐wavelength LPS lamps in favor of broad‐spectrum white LED lighting. This spectral shift represents an ecological experiment on a global scale, with potentially devastating results” [emphasis added]. 

Nocturnal Pollinators Go Dark under Street Lamps (2017 Scientific American). “Using night-vision goggles to observe and capture pollinators, the team found that those plots had 62% fewer visitations from insects than plots situated in darkness. The artificially lit plants also saw 29% fewer pollinator species.” 

Why Are Fireflies Disappearing? (2019 Firefly.org) 

LED Streetlights Are Good for the Earth, Bad for Humans and Wildlife (2016 TakePart.com) 

Too Much Light at Night Causes Spring to Come Early (2016 National Geographic) 

Ecological benefits of part-night lighting revealed (2019 Physics.org). “We know that light pollution significantly alters moth activity and this in turn is disrupting their role as pollinators. But what our study showed was that while full-night lighting caused significant ecological disruption, part-night lighting did not appear to have any strong effect on pollination success or quality.” 

The loss of ecosystem-services emerging from artificial light at night (2018 Journal of Chronobiology International). “Currently, this problem is not challenged sufficiently, even ignored by decision-makers at local and national levels, as well as other related organizations. … Using Artificial Light at Night (ALAN) as a loss of ecosystem-services will enable us to give it a realistic economic value thus an opportunity to re-evaluate the environmental cost of SWL efficient illumination. This will also help decision-makers to move to the next stage of illumination preferring sustainable illumination.” 

Spectral and duration sensitivity to light-at-night in ‘blind’ and sighted rodent species (2011 Joural of Experimental Biology). “…There is a strong association between LAN of the appropriate wavelength and adrenal endocrine responses, suggesting that LAN is a potential environmental stressor.” 

Ecological light pollution (2004 UrbanWildlands.org) 

Effects of street lighting technologies on the success and quality of pollination in a nocturnally pollinated plant (2019 Ecological Society of America). “These findings lend further support to previous studies suggesting that PN lighting regimes may provide the best solution to reducing the influence of artificial night lighting on nocturnal wildlife (Azam et al. 2015) and mitigating its ecological impacts. While our study, based on a single plant species, appears to suggest that plants may benefit from being situated under FN lighting, comparing this unexpected result to Knop et al. (2017) demonstrates the potential for ALAN to disrupt pollination systems across the community of plants, disproportionately strengthening some interactions and weakening others (Macgregor et al. 2015). Community‐level studies would be valuable to identify potential winners and losers from lighting, to determine the exact mechanisms underpinning the effects we have identified, and to understand how best to mitigate negative impacts.” 

Artificial Lighting at Night in Estuaries—Implications from Individuals to Ecosystems (2019 Springer.com) 

Nature, extent and ecological implications of night‐time light from road vehicles (2018 British Ecological Society). “The argument that mobile sources, and especially those from road vehicle headlights, are both contributing substantially to overall levels of artificial night‐time lighting and to the ecological impacts seems compelling. Moreover, emissions from headlights give rise to particular concerns because of their intensity, predominantly horizontal and long trajectory, prevailing broad “white” spectrum, and the pulsed nature of the illuminance of habitat and organisms that they cause.” 

LED lighting could have major impact on wildlife (2017 Univ. of Exeter). “The growth of LED lighting is an issue of global concern, and the number of documented impacts on the environment is growing rapidly. “Our research shows that local authorities might be able to manage LED lighting in a way that reduces its environmental impacts. We now need to establish whether this is the case for a greater variety of species. 

Artificial Night Lighting Affects Dawn Song, Extra-Pair Siring Success, and Lay Date in Songbirds (2010 Science Direct) 

Barriers and benefits: implications of artificial night-lighting for the distribution of common bats in Britain and Ireland (2015 Royal SocietyPublishing). “The potential implications of light pollution for the conservation of bats are considerable, particularly for many of our rarer, specialist bats. Our own research shows that even common species formerly considered to use street lighting may in fact show unexpected avoidance, depending on the extent of vegetation cover.” 

Draft National Light Pollution Guidelines for Wildlife Including marine turtles, seabirds and migratory shorebirds [in Australia] (2019 Australian Government) 

We Finally Know How Bright Lights Affect Birds Flying at Night (2017 Audubon) 

LED lighting increases the ecological impact of light pollution irrespective of color temperature (2014 Ecological Society of America). “Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light 3 air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations.” 

The dark side of street lighting: impacts on moths and evidence for the disruption of nocturnal pollen transport (2016 Wiley Online Library). “…We found significant effects of street lighting: moth abundance at ground level was halved at lit sites, species richness was >25% lower, and flight activity at the level of the light was 70% greater. Furthermore, we found that 23% of moths carried pollen of at least 28 plant species and that there was a consequent overall reduction in pollen transport at lit sites.” 

Light Pollution and Plants (2017 In Defense of Plants) 

Light at night disrupts diel patterns of cytokine gene expression and endocrine profiles in zebra finch (Taeniopygia guttata) (2019 Nature.com) 

Light Pollution Is a Driver of Insect Declines (2019 SSRN.com)

Anthropogenic Light Disrupts Natural Light Cycles in Critical Conservation Areas (2019 SSRN.com). “To facilitate biological interpretation of these levels of anthropogenic illuminance observed globally, we undertook a systematic literature review of animal responses to changing nocturnal light levels. Known biological effects from the current anthropogenic illuminance levels range from behavioral and physiological alterations to increased mortality, which have been documented in 117 species from 23 orders and 8 classes.” 

Light pollution is key ‘bringer of insect apocalypse’ (2019 TheGuardian.com). “Simply turning off lights that are not needed is the most obvious action, he said, while making lights motion-activated also cuts light pollution. Shading lights so only the area needed is illuminated is important, as is avoiding blue-white lights, which interfere with daily rhythms.” 

Light pollution is hot-wiring spring, scientists say (2016 LUX Magazine)

 Anthropogenic activity expressed as ‘artificial light at night’ improves predictive density distribution in bird populations (2019 Science Direct)

Light Pollution and Animals (2016 NOAO)

 Rapid Assessment of Lamp Spectrum to Quantify Ecological effects of Light at Night (2018)

How light pollution affects the lives of garden creatures (2020 Financial Times)

Does light pollution affects birds? (2013 International Max Planck Research School)

Research Confirms that Light Pollution Can Suppress Melatonin Production in Humans and Animals (2019 LED Magazine) “At high light levels, melatonin production is suppressed. In darkness, melatonin is produced. The sensitivity threshold for humans is 6 lux – street lighting is typically higher. …Even very low illuminance levels can suppress melatonin production for some vertebrate classes: in fish the threshold is 0.01 lux, in rodents 0.03 lux and in sensitive humans 6 lux; pure blue light showed much lower thresholds. For comparison, the illuminance levels at night: on a starry night, the illuminance is 0.001 lux. On a full-moon night it reaches a maximum of 0.3 lux. The skyglow of a city, a form of light pollution, can reach illuminances of up to 0.1 lux, and outdoor lighting on the order of 150 lux.”

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates (2019 Sustainability) “Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels.”

 

LED Lighting: Good News Today Bad News Tomorrow?? (2016 C&W Energy Solutions) We Do Not Want the LEDs of Today To Be the Asbestos Cases of 2040.

Circadian Light (removes blue wavelengths at night) 

CW Energies (“Star Friendly Lighting” brochure)

Dark Sky Reflector for Large Acorn Globe Light 

Eyesafe (Blue Light)

Eyesafe (blue-block Dell computer screens)

Eyesafe (Research)

Five key discoveries that have revolutionized the medical science of lighting 

Human-Centric Lighting Society 

Illuminating Engineering Society 

Illuminating Engineering Society’s Lighting Library 

InvisibleShield Glass (blue-block screen protectors for iPhones ~$50)

Joint IDA-IES Model Lighting Ordinance (2011) 

LightAware  “LightAwareJoint IDA-IES Model Lighting Ordinance (2011)  was founded to respond to the needs of those whose lives and health have been profoundly affected by the ban on incandescent lighting and the development of new forms of light.”  

Lighting Research Center 

Lumia: Streetlights Replacement Problems and Solutions (2015). “Glare has a strong effect on the normal visual function, causing a serious threat to safety. The accumulative effect of glare also threatens the physiological health of the human body, caused by what is defined as blue light. These issues impact the eye due to the toxic effect of blue light, the risk of glare erupting from bad designs and the poor choice of components in the streetlight.” 

Lutron Human Centric Lighting 

Philips Signify (Lighting Courses and Webinars)

Seoul Semiconductor’s “SunLike” Technology 

Astronomy Clubs in Montana (online information)

Big Sky Astronomy Club (Kalispell) 

Central Montana Astronomy Society (Great Falls) 

Flathead Valley Junior Astronomers (Kalispell)

Helena Astronomical Society (Helena) 

Kootenai Stargazers Astronomy Club (Libby) 

The Mining City Astronomers (Butte) 

Montana Astronomy Clubs and Organizations (online information)

Montana Starwatch (online resource)

Montana Starwatch Calendar (MT astronomical meetings and events) 

Neuman Astronomical Society (Carroll College, Helena) 

Southwest Montana Astronomical Society (Bozeman) 

The Cottontail Observatory (Twin Bridges) 

Western Montana Astronomical Association (Missoula) 

Yellowstone Valley Astronomy Association (Billings, currently inactive) 

New Development Illuminates Kalispell’s Lighting Ordinance (Daily Interlake 2018) 

Montana’s Dark Skies Spur Astrotourism (Daily Interlake 2019) 

Walkerville mine boasted first light bulb in Montana (Montana Standard 2016) 

Montana’s Energy History (Montana DEQ undated) 

Ancient cultures may have used medicine wheel to connect stars, stories, Bozeman researcher says (Billings Gazette 2019) 

Yellowstone by Night (George Wright Forum 2001)

‘Astronomy Night’ at MSUB brings space into focus (2015 Billings Gazette)

The Heart of Darkness: Finding wildness and wonder in the night sky (Montana Outdoors 2014) 

The Great Western Starry Way [Glacier to Grand Canyon & beyond] (Consortium for Dark Sky Studies undated)

Gazette opinion: Marketing Eastern Montana vacations (Billings Gazette 2019) 

East Helena moves to LED streetlights (2019 KTVH.com) 

NorthWestern Energy replacing and recycling 43,000 streetlights across Montana (2019 KXLH.com)

‘Brighter than expected:’ Love Lane homeowners file petition against new street lights (2019 KPAX.com). “We don’t like the lights,” Triemster says. Triemster says when the lights came on for the first time, everyone knew. “They’re about like a parking lot in a Walmart place or maybe brighter than that,” Triemster says. “Not quite as bright as a football field but you could play football out here.” 

“Glacier National Park after dark“ (2016 Big Sky Outdoors) (30-minute program with fishing report in the middle)

Recommended Lighting Practices: A Collaborative Effort by the Permian Basin Petroleum Association,  the Texas Oil and Gas Association, and the McDonald Observatory (2018)

Shedding (Less) Light on the Dark (2018 Hart Energy) (17:25 minute video)

Protecting the West Texas Dark Skies (2018 McDonald Observatory) (all about oil wells)

McDonald Observatory, Oil and Gas Organizations Collaborate to Protect Night Skies (2018)

Upgraded Rig Lighting Improves Night Time Visibility While Reducing Stray Light and the Threat to Dark Skies in West Texas (2015, One Petro) (abstract only)

McDonald Observatory works with energy companies to stop light pollution (2017 My San Antonio)

When Staying in the Dark is the Brightest Idea (2017 Oil & Gas Magazine)

Dark Skies Initiative (undated, McDonald Observatory) 

LED Lighting for Oil and Gas Facilities (2015, IEEE Transactions on Industry Applications)

Industrial Lighting Safety, Can You See the Problem? (2006 Record of Conference Papers – IEEE Industry Applications Society 53rd Annual Petroleum and Chemical Industry Conference) (abstract only) This paper demonstrates that an improved understanding of the industrial lighting environment, and the tasks that workers have to perform in these environments, may improve safety and health performance. It shows how occupational health & safety and the Illumination Engineering Society (IES) safe lighting conditions and standards are often misinterpreted or ignored and the effects this may have.

The Influence of Street Lighting on Crime and Fear of Crime (London Crime Prevention Unit 1991). “The timeframe for ‘before’ and ‘after’ comparison was a full twelve months in each case, while the total database comprised over 100,000 crimes reported to the police. The team from the University of Southampton who carried out this research concluded that, as deployed on a broad scale, better street lighting has had little or no effect on crime. In their words, “the dominant overall conclusion … was of no significant change” On the other hand, they did find that the improved street lighting was warmly welcomed by the public, and that it provided a measure of reassurance to some people – particularly women – who were fearful in their use of public space” [emphasis added].

Burglary Prevention for your Home (2018 Houston TX Police Department brochure) Non glare soft lighting and downward shielding is optimal when selecting lighting products to achieve optimal visual results (page 2 under “Exterior and Landscape”). 

A Rationale for the Mandatory Limitation of Outdoor Lighting (Astronomical Society of Victoria 2008). “By the early 1990s, scientific reviews in the USA and UK had established that outdoor lighting was ineffectual for crime prevention. However, common belief in the efficacy of lighting against crime seems to have persisted, perhaps because of confusion with the commonly experienced beneficial effect of lighting in reducing the fear of crime” (p.33)[emphasis added].

Outdoor Lighting and Crime, Part 2: Coupled Growth (Astronomical Society of Victoria 2003). “Although the presence of light tends to allay the fear of crime at night, the balance of evidence from relatively short-term field studies is that increased lighting is ineffective for preventing or deterring actual crime.  In this second part, available evidence indicates that darkness inhibits crime, and that crime is more encouraged than deterred by outdoor lighting.  A new hypothesis is developed accordingly.  Additional quantitative evidence supports the hypothesis.  Excessive outdoor lighting appears to facilitate some of the social factors that lead to crime” [emphasis added]. 

Street Lights and Crime: A Seemingly Endless Debate (Citylab.com 2014). “According to a 2007 systematic review of lighting experiments in American cities, increased street lighting in Indianapolis, Harrisburg, New Orleans, and Portland, Oregon, did not coincide with a drop in the affected areas’ crime rates, but it did in Atlanta, Milwaukee, Kansas City, and Fort Worth. Yet even in U.S. cities where lights “worked,” they didn’t appear to work consistently: While Fort Worth saw a decrease in all types of crime, Kansas City saw a decrease only in violent crime.” 

Humans cling to their primal fear of the dark (Astronomy 2015). “The statistics showed no link between accidents and dimming, reducing, or changing the style of streetlights… The researchers looked at lighting’s effect on crime trends. In regions of reduced lighting, they found, there was no increase in burglary, auto theft, robbery, violence, or sexual assault. And, in fact, if you’re worried about being victimized, your concerns are often better placed in broad daylight. That’s when — in certain cities at least — crime statistics show you’re most likely to be assaulted (though you are often more likely to get shot at night). Most home break-ins also happen during the day. And the hours just before dawn — the darkest — are also often those with the least crime… In the end, this white-light night’s perceived protection has become a greater threat than anything that goes bump within it.”

Does streetlighting cut crime? (LuxReview.com 2015). “What’s even more telling is that the Association of British Insurers does not recommend outdoor lighting as a crime deterrent. Indeed, insurance companies do not offer a reduction in your premiums if you have security floodlights, because there is little evidence to suggest that lighting reduces crime… Manufacturers love to claim that their lights will make us safer. But the latest evidence suggests otherwise.” 

In New York, crime moves faster than lights (LuxReview.com 2015). “The knifers and muggers started scattering to new locations after New York installed temporary high-powered lights at the 15 in preparation for permanent new lighting, while also adding other security measures. ‘As a result, between Jan. 1 and July 26, crime fell at 10 of the 15, stayed flat at one and rose at four compared with the same period last year,’ the Daily News reports.”

Reducing Crime Through Environmental Design: Evidence from a Randomized Experiment of Street Lighting in New York City (Semantic Scholar 2019). “After accounting for potential spatial spillovers, we find that the provision of street lights led, at a minimum, to a 36 percent reduction in nighttime outdoor index crimes.” 

Improving Street Lighting to Reduce Crime in Residential Areas (Cops.usdoj.gov 2008). “The effects of improved street lighting are likely to vary  in different conditions. In particular, they are likely to be greater if the existing lighting is poor and if the improvement in lighting is considerable. They may vary according to characteristics of the area or the residents, the design of the area, the design of the lighting, and the places that are illuminated.” 

Streetlights Don’t Actually Prevent Crime (Gizmodo.com 2014). “There seem to be plenty of good reasons to dim or turn streetlights off completely, but the perceived fear of darkness might be enough for cities to keep them blaring bright… But if anything, having a special, police-sanctioned night where it’s “safe” to go out after dark reinforces the idea that night is dangerous and that neighbors shouldn’t really be out the rest of the time when the sun goes down. It proves how hard the battle will be to win for scientists and environmentalists who want to take back the night.” 

Panel Paper: Bright Lights, Safe Nights? the Effect of LED Street Lights on Crime in Los Angeles (Association for Public Policy Analysis and Management 2018). “So, a 1% increase in the intensity of LEDs corresponds to a 0.1% increase in property crime rates… We find that a 1% increase in the intensity of LEDs corresponds to a modest 0.03% decline in violent crime rates.” 

Evidence regarding the impact of the street lighting on crime and antisocial behavior (Cambridgeshire Research Group 2015). “The best conclusion that can be drawn from the research literature is that the general benefit of street lighting in reducing crime is unproven but in very specific circumstances, where there is an existing crime hot-spot and current lighting is poor then improvements may prove beneficial.” 

The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis (Epidemiol Community Health 2015). “This study found little evidence of harmful effects of switch off, part-night lighting, dimming, or changes to white light/LEDs on road collisions or crime in England and Wales.” 

The Chicago Alley Lighting Project: Final Evaluation Report ( Illinois Criminal Justice Information Authority 2000). “When the number of reported incidents for this one year analysis are examined, the data indicated that there were 428 total incidents reported in the pre-installation period and 519 total incidents in the post-installation period – an increase of 21 percent in reported offenses between the pre- and post-period test. Each of the three crime categories experienced an increase in the number of reported incidents between the pre and post-installation period. Violent Index offenses increased 14 percent (119 to 136), property Index offenses increased 20 percent (30 to 36) and non-Index offenses increased 24 percent (279 to 347).” 

What actually happens to crime ‘when the lights are on’ (Washington Post 2017). “Although it’s an assumption that many of us take for granted, evidence is mounting that nighttime brightness may do little to stop crime, and in some cases may make it worse.” 

Higher concentrations of streetlights do not guarantee safety: study (Physics.org 2017). ”In fact, [in Houston TX] areas with higher densities of lights experienced 60 percent more nonviolent crimes on average than areas with low concentrations of streetlights (fewer than 15 streetlights per mile of roadway).”

Stargazing Versus Safety: The Dilemma of Exterior Lighting (2018 Leducation.org) 

Missoula Outdoor Lighting Ordinance [Number 3341] (2007) 

Missoula Outdoor Lighting Ordinance [Number 3582] (2016) 

Shedding Light on Missoula’s Outdoor Lighting Ordinance (undated)

Kalispell Outdoor Lighting Standards [Chapter 27.26 pages 127-134] (2005) 

Whitefish Outdoor Lighting Standards [Zoning Regulations 11-3-25] (2006) 

Bozeman Lighting Standards [Division 38.570] (undated)

[Livingston, MT]  Night Sky Protection Act (2006)

Helena, Montana City Code. Title 10: Lighting Standards (2019). “Only an owner or occupant of private property containing light trespass from a light may file a complaint with the city.” 

Flathead County Zoning [Section 5.12 Yard, Street and Security Lighting (2017) 

Montana Code: Standards For Permitted Advertising (generally covers billboard lighting) 

Montana Code: Spot Lamps, Fog Lamps, And Auxiliary Lamps (auxiliary motor vehicle lights) 

Montana Code: Environmental Protection (covers air and water pollution, lacks protection from light pollution)

First-Dark-Sky-City (FDSC) Recommendations for roadway and commercial lighting (undated). Recommended light fixtures, “For communities or lighting designers seeking the moderate dark-sky impacts of HPS-like PCA LED (or those using lowest-impact NBA LED for roadway and parking, but seeking an alternative to high-impact white LED in applications needing color rendition)…”

New American Petroleum Institute ANSI Standard has Implications on Workplace (2019) (less than 2% blue light content at night!) 

Outdoor Lighting Codes (2019) 

Dark Sky Planning, An Introduction for Local Leaders (2018) (Utah Community Development Office) 

IDA Starts New LED Public Outreach Program (2016) 

Dark Sky Assessment Guide (2018) (Utah Community Development Office)

Utah municipal light ordinances 

Promoting Quality Outdoor Lighting in Your Community (from Maine) 

States Shut Out Light Pollution (all states with lighting laws) 

Flagstaff, AZ Outdoor Lighting Standards (2011) 

New Mexico Night Sky Protection Act (1999) 

New Mexico Lighting Laws (state, county, city)

Night Sky Friendly Business Recognition Program (undated, from central TX) 

Dark Sky Lighting Ordinance Walkthrough

Lighting Code Basics 

An Overview: International Dark Sky Communities

Dark Skies: [Texas] Governor passes HB 4158 (2019) 

Reducing Acadia [National Park’s] Light Pollution (2016) 

Lighting – Great Streets of St. Louis (undated) 

Joint IDA-IES Model Lighting Ordinance (2011) 

Pattern Outdoor Lighting Code (2011) 

Recommended Light Levels 

Outdoor Lighting Ordinances: Tools to Preserve the Night Sky (2011) 

Royal Astronomical Society of Canada Dark-Sky Site Application Requirements (2018) 

Guidelines for Outdoor Lighting in RASC Dark-sky Preserves and IDA Dark Sky Places (2012) 

Light Spectrum and Light Pollution (2019 FlagstaffDarkSkies.org). “The bottom line is simple, if unexpected to many: Yellow or amber light sources (such as HPS, PCA LED or, the best, LPS* or NBA LED) cause the least sky glow by far, as little as one half or even one quarter that of the best (lowest color-temperature) white light sources. The other side of the coin is that all white light sources (even “low CCT”) cause greater impact, usually much greater.” 

Is Blue Light Bad For Your Health? (2017 Web MD) “The more research we do, the more evidence we have that excess artificial light at night can have a profound, deleterious effect on many aspects of human health,” says Czeisler, who is also director of sleep medicine at Harvard Medical School. 

Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study) (2018). “Both prostate and breast cancer were associated with high estimated exposure to outdoor ALAN in the blue-enriched light spectrum.” 

The impact of light source spectral power distribution on sky glow (2014). “High correlated color temperature LEDs and metal halide sources produce a visual brightness up to 8× brighter than low-pressure sodium and 3× brighter than high-pressure sodium when matched lumen-for-lumen and observed nearby. Though the sky brightness arising from blue-rich sources decreases more strongly with distance, the visual sky glow resulting from such sources remains significantly brighter than from yellow sources out to the limits of this study at 300 km… At 300 km the ratios decrease due to the greater extinction of the bluer sources, but remain 3–4× that from LPS and 1.6–2.4× that from HPS.”

Exposure to ‘white’ light LEDs appears to suppress body’s production of melatonin more than certain other lights, research suggests (2011 Science Daily). “Exposure to the light of ‘white’ LED bulbs appears to suppress melatonin five times more than exposure to the light of high pressure sodium bulbs that give off an orange-yellow light, according to new research.” 

AMA Report Affirms Human Health Impacts from LEDs (2016). “The report details findings from an increasing body of scientific evidence that implicates exposure to blue-rich white light at night to increased risks for cancer, diabetes and cardiovascular disease. Not only is blue-rich white LED street lighting five times more disruptive to our sleep cycle than conventional street lighting, according to the report, but recent large surveys have documented that brighter residential nighttime lighting is associated with reduced sleep, impaired daytime functioning and a greater incidence of obesity.” 

American Medical Association warns of health and safety problems from ‘white’ LED streetlights (2016) “Can communities have more efficient lighting without causing health and safety problems?” 

AMA adopts guidance to reduce harm from high intensity street lights (2016) 

The impact of artificial light at night on nocturnal insects: A review and synthesis (2018 Wiley Online Library). “Widespread nocturnal artificial illumination radically disrupts the habitats of night‐active species. …The severity of impact will depend on the degree of overlap between the spectral sensitivity of the insect in question and spectral emission (and intensity) of the particular ALAN source (Gaston et al., 2015). Recently, many urban areas have begun to phase out monochromatic long‐wavelength LPS lamps in favor of broad‐spectrum white LED lighting. This spectral shift represents an ecological experiment on a global scale, with potentially devastating results” [emphasis added]. 

LED lighting increases the ecological impact of light pollution irrespective of color temperature (2014 Ecological Society of America). “Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light 3 air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations.” 

The Dark Side of LED Lightbulbs (2012 Scientific American) 

Visibility, Environmental, and Astronomical Issues Associated with Blue-Rich White Outdoor Lighting (2010 IDA white paper). “This paper summarizes atmospheric, visual, health, and environmental research into spectral effects of lighting at night. The physics describing the interaction of light with the atmosphere is long-established science and shows that the increased blue light emission from white lighting sources will increase visible sky glow and detrimental effects on astronomical research through increased scotopic sensitivity and scattering.” 

Blue-free white light breaks the paradigm of circadian lighting (2017 LEDs Magazine). “…Exposure to light in the evening can have unwanted effects. Research has shown that common indoor lighting conditions (100 lx and above) are enough to significantly impact the circadian cycle. Such effects persist for several hours after light is turned off, and can thus delay the onset of sleep. Display light from phones and tablets is an additional cause for concern. This worry has become even more acute with the spread of LED lighting, which uses blue-pump LEDs whose intense blue radiation can be especially impactful.” 

Is it time to say goodbye to blue-pump LEDs? (2019 LEDs Magazine). “As the deployment of PC-LEDs became more widespread, so did reports in the media relating to potential negative impacts of their associated strong blue emission, from photochemical blue-light retinal injury and age-related macular degeneration to disruption of the circadian rhythm… Recall that the spectrum of the PC-LED is not the only aspect in question but also the extremely high radiance and luminance. Decreasing blue-light radiance can also be achieved by avoiding direct viewing of PC-LEDs.” 

Bright lights hiding problems (2019 Otago Daily Times). “While we at least talk about the problem, I received a desperate call for help from a citizen of India. According to this message, the Government is installing very bright LED lights (6500K) and the first residents are experiencing the negative effects through light spill to their homes. This could potentially affect 1.3billion people.” 

Blue light Aotearoa: How does blue light affect us? (undated, excellent!) 

Light plans progress amid concerns (2019 Otago Daily Times). “The summary, which had been released following a official information request, included more than 30 responses, almost all of them opposed to the new lights. The submitters’ concerns included that the new lights would emit a colder, blue light that was ”blindingly bright” and risked creating a health and safety hazard. Introducing them could even leave the council liable for their negative effects in future, and the change should be reconsidered, other submitters argued.” 

LEDs: ANSES’s recommendations for limiting exposure to blue light (2019 French Agency for Food, Environmental and Occupational Health & Safety). “The new scientific data confirm the 2010 result regarding the toxicity of blue light to the eye, which can lead to failing eyesight. They show short-term phototoxic effects associated with acute exposure and long-term effects associated with chronic exposure, which increase the risk of developing age-related macular degeneration (ARMD)… In view of the results of its expert appraisal, ANSES is making a series of recommendations to limit the population’s exposure to blue light. The Agency reiterates the importance of favouring “warm white” domestic lighting (colour temperature below 3000 K). To prevent the disruptive effect on biological rhythms, it recommends limiting the exposure of people – children in particular – to the blue-rich light of LED screens (mobile phones, tablets, computers, etc.) before bedtime and at night.” 

Hidden Blue Hazard? LED Lighting and Retinal Damage in Rats (2014 Environmental Health Perspectives). “Among the most popular household LEDs are products that employ a chip emitting blue light, which is surrounded by a yellow phosphor coating. Although the resulting light looks white to the naked eye, it can feature a spike in the blue end of the spectrum, at wavelengths of 460–500 nm. Light of this wavelength has been shown to have unique physiological effects, some positive, some negative. White LEDs, as a new source of exposure to blue light, initially prompted concerns about potential changes in melatonin production and disruption of human sleep cycles. More recent research considers the direct effect of this light on the eye, including the risk of ongoing damage to retinal cells… The retinas of rats exposed to either blue or cool white LED light showed evidence of retinal damage and cell death after 9 days of exposure.” 

The Color of Lights: More Than Meets the Eye (2011 IlliniosLighting.org) (critical to understanding issues with blue light!). “But there is strong scientific evidence that most, if not all effects of light aren’t just a matter of whether it is light or dark; the spectral qualities of light are actually the determining factors… Research shows that the amount of perceived discomfort glare from a light source, especially at night, is strongly dependent on the color composition of the light… We see a significant increase in perception of glare with a change in light color, especially toward the blue end of the spectrum… This color-related aspect of glare has been witnessed by anyone who has been annoyed by the oncoming headlights of vehicles equipped with the new blue-rich high-intensity discharge lamps… Light with wavelengths shorter than 500 nanometers seems clearly to pose problems in human visual perception and health, and in other areas, including skyglow… The only prudent solution for minimizing the total negative effects our artificial lighting has on the environment is to re-think how we apply light at night, and adopt the practice of only applying the minimal levels needed, focused only on the areas where we have tasks to accomplish, only at the times we are active there. Only that practice can minimize all the unintended negative effects of manmade light at night. But where we do need to apply light, color matters.”

“Human-centric lighting” may be the key to feeling better at work (2018 Quartz.com). “Too little light from the blue end of the visible spectrum during the day, or too much of that same light at night, research suggests, can cause an internal clock to slip off beat, setting off a cascade of potential consequences.” 

Age of Enlightenment: The Promise of Circadian Lighting (2018 Undark.org) (excellent!). “Scientists believe that exposure to bright, blue-rich white light during the day, and to softer, amber hues at night, helps restore the human body’s natural circadian rhythm, a deeply ingrained, physiological drumbeat that, many experts argue, has been disrupted to ill-effect by our constant exposure to standard incandescent or fluorescent lighting — and more recently, to the relentless glow of electronic screens.” 

A Comparison of Blue Light and Caffeine Effects on Cognitive Function and Alertness in Humans (2013 PLOS ONE). “Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants.” 

Seeing Blue (2010 DarkSky.org) (well written!). “Increased scattering from BRWL [blue rich white light] sources leads to 15% to 20% more sky glow detectable by an astronomical instrument than high-pressure sodium (HPS) or low-pressure sodium (LPS). Due to the eye’s increased sensitivity to blue light at lower levels, the visual brightness of sky glow produced by BRWL can appear three to five times brighter than it appears with HPS and up to 15 times as bright when compared to LPS.” 

Now the LRC calls blue a ‘significant’ melatonin suppressor (2019 LEDs Magazine) 

Worry about the amount of light at night more than the blue wavelengths (2019 LEDs Magazine) 

Worried About LED, OLED Blue Light Eye Damage? Dell Is (2019 Forbes). 

LED light can damage eyes, health authority warns (2019). “The report distinguished between acute exposure of high-intensity LED light, and “chronic exposure” to lower intensity sources. While less dangerous, even chronic exposure can “accelerate the ageing of retinal tissue, contributing to a decline in visual acuity and certain degenerative diseases such as age-related macular degeneration,” the agency concluded… Because the crystalline lens in their eyes are not fully formed, children and adolescents are particularly susceptible to such disruptions, the ANSES reports noted…  For domestic lighting, ANSES recommended buying “warm white” LED lighting, limiting exposure to LED sources with a high concentration of blue light, and avoiding LED screens before bedtime.” 

Global rise of potential health hazards caused by blue light-induced circadian disruption in modern aging societies (2017). “Children and adolescents are at particular risk for long-term exposure, but adults, including the aged, should not be forgotten. Due to the unavoidable 24/7 access and exposure to blue-enriched light, we need to provide adequate awareness among people based on the available scientific evidence. We propose that blue-enriched light, in particular but not exclusively from blue-containing LEDs, is a potential and an avoidable risk factor for health disorders.” 

Acute exposure to evening blue-enriched light impacts on human sleep [abstract  only] (2013 Journal of sleep research). “Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode.” 

Blue light from light-emitting diodes directed at a single eye elicits a dose-dependent suppression of melatonin in horses (2013 Science Direct). “The use of artificial light to advance the breeding season in mares is common practice within the equine industry. … The threshold level of low wavelength light required to inhibit melatonin production in the horse lies between 3 and 10 lux. Melatonin inhibition can be achieved by exposing a single eye to low wavelength blue light.” 

What is the blue light from our screens really doing to our eyes? (2014 GIGAOM). “An eye doctor says he’s recently seen a few 35-year-old patients whose lenses, which are typically clear all the way up until around age 40, are so cloudy they resemble 75-year-olds’. A sleep doctor says kids as young as toddlers are suffering from chronic insomnia, which in turn affects their behavior and performance at school and daycare. A scientist finds that women who work night shifts are twice as likely to develop breast cancer than those who sleep at night. What do all these anecdotes have in common? Nighttime exposure to the blue light emanating from our screens.” 

The Effects of Blue Light on Ocular Health (2000 Texas School for the Blind). “There is mounting medical evidence that prolonged exposure to blue light may permanently damage the eyes, contribute to the formation of cataracts and to the destruction of cells in the center of the retina… Ham et al. (1980) and Gorgels and van Norren (1995) pointed out that actinic, or photochemical damage to retinal tissue, is more a function of wavelength than either intensity or duration. Gorgels and van Norren, after examining rat retinas damaged by blue light, wrote “duration had no influence on damage threshold dose, nor on morphology. We conclude that wavelength (and neither irradiance nor duration) is the factor responsible for the encountered morphological differences”(p.859).” 

Removal of the blue component of light significantly decreases retinal damage after high intensity exposure (2018 PLOS One) 

Blue light triggers sweet tooth in rodents, study shows (2019 DW.com) 

Daily blue-light exposure shortens lifespan and causes brain neurodegeneration in Drosophila (2019 Nature). “A surprising outcome of our study is that blue light not only damaged the retina, but also caused neurodegeneration in the brain… We hypothesize that light-induced brain neurodegeneration may be the main cause of the decreased vertical mobility and reduced lifespan.” 

LED Lighting and Dark Skies (2019 FlagstaffDarkSkies.org). “For sky glow light pollution, the conclusion is unambiguous: research shows that white light – of any kind (CCT) – has substantially greater impact on sky glow than yellow light (see our page Lamp Spectrum and Light Pollution). Compared to the currently prevalent high-pressure sodium lights, even the lowest-impact white LEDs (though higher-impact LEDs are far more widely used) will increase visible sky glow lumen-for-lumen 2.2x – more than double. Compared to PCA LED the increase is over 3x, and compared to the most night-friendly light, low-pressure sodium or NBA LED, the increase is 6x. This is not 6% nor even 60% – it is 6x or 500%! The most optimistic predictions for decreased lighting amounts that might be achieved with LEDs (due to better optical control) cannot compensate for this.” 

Street-light CCT debate will continue, but it is misguided (2017 LEDs Magazine). “The DOE emphasized a point I have made repeatedly. The problem is operational light levels. Street lights can and should be dimmed. And poor lighting design contributes more to sky glow than LED technology at cool CCTs” [emphasis added]. 

LED Streetlights Are Giving Neighborhoods the Blues: Early adopters of LED street lighting are struggling with glare and light pollution (2016 IEEE Spectrum). “When my city of Newton, Mass., announced plans to install LED streetlights in 2014, I was optimistic. I’m all for energy conservation, and I was happy with the LED bulbs in my home office. But months later, returning from a week’s vacation in rural Maine, I was shocked to find my neighborhood lit by a stark bluish blaze that washed out almost all of the stars in the night sky. 

Street Lighting and Blue Light: Frequently Asked Questions (2017, U.S. Dept. of Energy) 

Bright idea? Light pollution fears shadow NCC plan to light up capital (2017 Ottawa Citizen). “’The 4000K light produces 16 times more light pollution than the 2000K,’ says Dr. James D. Lowenthal, professor and chair of the astronomy department at Smith College in Northampton, Mass. The more blue the light is, the more consequences there are for human health and on the ecosystem, notwithstanding the impact on light pollution and sky glow.” 

LED Streetlights Are Giving Neighborhoods the Blues (2016 IEEE Spectrum). “Lately, lighting companies have introduced LED streetlights with a warmer-hued output, and municipalities have begun to adopt them. Some communities, too, are using smart lighting controls to minimize light pollution. They are welcome changes, but they’re happening none too soon: An estimated 10 percent of all outdoor lighting [PDF] in the United States was switched over to an earlier generation of LEDs, which included those problematic blue-rich varieties, at a potential cost of billions of dollars.” 

Street Lighting and Blue Light, Frequently Asked Questions (2017 Energy.gov). “If done well, dimming is an effective approach for addressing the potential influences of shortwavelength content. Relatively few dimming systems for street lighting have been installed in the U.S. to date, but the existing installations have confirmed the anticipated benefits of this approach. For example, the city of Cambridge, MA, dims its 4000 K LED streetlight system by 50% after midnight (Figure 8), with corresponding reductions large enough that the system subsequently produces less melanopic content than the HPS system it replaced.” 

Research on retina damage sparks fresh LED health scare (2013 LUX Magazine) Dr. Celia Sanchez Ramos of Complutense University, who has been investigating what’s known as the ‘blue light hazard’, predicted ‘an epidemic’ of retina problems due to increased exposure to LED lighting.

Apple move ‘acknowledges blue light dangers’ (2016 LUX Magazine)

Lumican Dark Sky Series

Star-Friendly Lighting (C&W Energy Solutions)

EnGoPlanet Smart Solar Street Light

Retrofit: Turning Street Light Poles from energy consumers to solar energy providers (2019)

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2,700 Kelvin

2,200 Kelvin Streetlights

More lighting alone does not create safer cities. Look at what research with young women tells us (2019 The Conversation) 

Commercial and Roadway Lighting Tips (2018 FlagstaffDarkSkies.org). “Many in the lighting industry claim that white light provides better vision and by implication improved safety on roadways… Some of these tests showed differences in performance with different kinds of lights, but we consider it important that the more recent work, based on more realistic test conditions (a real car on a test road vs. a person in a driving simulator) show small or even no effect of spectrum. But the conclusion that white lighting is better is not supported…” 

Effect of illuminance and spectrum on peripheral obstacle detection by pedestrians (2015 Lighting Research & Technology). “Detection performance increased with illuminance, reaching a plateau at 2.0 lux.” 

Perceptions of safety at night in different lighting conditions (2000 Lighting Research & Technology). “Taken together, these studies indicate that an average horizontal illuminance on a parking lot surface or street sidewalk of about 30 Ix provides enough light to ensure that perceptions of safety are close to what they are in daylight. The light spectrum is a minor factor relative to illuminance.“ 

Road lighting research for drivers and pedestrians: The basis of luminance and illuminance recommendations (2017 Lighting Research & Technology). “Recommendations for the amount of light do not appear to be well-founded in robust empirical evidence, or at least do not tend to reveal the nature of any evidence.” 

Evaluation of pedestrian reassurance gained by higher illuminances in residential streets using the day–dark approach (2018 Lighting Research & Technology). “…The results suggest a minimum horizontal illuminance of approximately 2.0 lux.” 

Assessment of pedestrian discomfort glare from urban LED lighting (2016 Lighting research and technology)

On University of Utah campus, where foot traffic goes all night long, a push against light pollution (2018). Dimmer lights may actually improve safety, Willson said. “Wasteful lighting can be too glary in some places and dark in between the fixtures,” Willson said. “If it’s done properly, it’s a safer environment. With lower levels, your eyes will adjust. You can see better; the color rendition is better.” (https://www.sltrib.com/news/2018/05/29/on-university-of-utah-campus-where-foot-traffic-goes-all-night-long-a-push-against-light-pollution/?fbclid=IwAR2AM8o1nVyun4saEP8BXMidnhbPFCGx5xtiYInqV2cc6qdpOJL7ar0mkiQ)

The Future of Roadway Lighting (2015 Federal Highway Administration). “These traditional approaches to lighting design result in significant over-lighting of roadways and excessive energy usage. Adaptive lighting, that is, adjusting illumination levels based on the needs of roadway users, offers an approach to overcome these challenges.” 

This is why pedestrians and cyclists disappear when it starts getting dark (2017 New Statesman)

Our street lighting doesn’t need to be this bad (2018). “Lamps are too bright mainly because, over time, they get dirty and less efficient, so utility companies and lighting designers opt for unnecessarily intense lights.” (https://www.popsci.com/street-lighting-science/)

Weighing the costs of LED street lights (2019 EDN Network). “For any municipal engineers looking to get additional information, the MSSLC is the main source, including engineering data on the many types of illumination. The DOE set up the MSSLC in 2014 to help support cities considering the use of LEDs.”

The science of street lights: what makes people feel safe at night (2018 The Conversation). “Street lighting can improve the quality of neighborhood life by making people feel safer – but, even so, it would be unwise to flood our streets with light at night.” 

Seattle’s new LED-lit streets: Blinded by the lights (2013 Crosscut) “The bad news: despite extensive, much-touted prior testing, the city has been installing these new streetlights in crude one-size-fits-all fashion with little regard to Seattle’s hilly terrain, bombarding many residents, outside and sometimes inside their homes, with intrusive, blinding glare. The other good news: It can and will correct these problems — if you call to complain.” 

HPS to LED Conversion – A City of Phoenix Experience (2013, calculations from before public convinced city to switch from 4,000K to 2,700K LEDs) 

[Phoenix] LED Street Light Program (after public convinced city to switch from 4,000K to 2,700K LEDs) 

 

Davis Will Spend $350,000 To Replace LED Lights After Neighbor Complaints (2014 CBS Sacremento). “After the city installed 650 new LED lights in May designed to save money, several neighbors complained about them, so Davis city leaders will spend $350,000 to replace the lights.” 

Grants fund cities’ switch to LED bulbs (2018 Spokane Spokesman-Review) 

Weighing the costs of LED street lights (2019 EDN Network) 

Residential LED Street Lights [in Portland] (2018 City of Portland). “Initially, the City did receive some complaints from residents that the lights were too bright… PBOT now sets all residential units at the lowest output level.” 

Phoenix’s LED Street Light Conversion Moves Forward (2016 City of Phoenix). “The Council also revised the city’s standard color temperature (kelvin level) for street lights from the current 4,000 kelvin to 2,700 kelvin, which is considered a “warmer” color temperature for LED lights. The revision in the standard color temperature (kelvin level) for street lights was based on American Medical Association guidelines and extensive community input, potential environmental issues, technical lighting standards, and projected energy savings.” 

In switchover to LED streetlights, Tucson is aware of sleep concerns (2016 Tucson.com). “Tucson, which plans to convert most of its outdoor municipal lighting to LED, or light-emitting diodes, this year, has already chosen the least “blue” lighting that is commercially available and plans to dim those lights when not needed for safety reasons.” 

Cambridge, MA – LED Streetlight Retrofit Project (2015 Volt.org). “The efficacy delta between warm and cooler CCT continues to shrink. However this delta is dwarfed by the energy savings possible from dynamically adapting  fixture output to match IES minimum illumination recommendations for traffic conditions, and stopping the common practice of over-lighting.  Additionally, cities should not underestimate how dramatic the shift in color from HPS, at about 2000K CCT, to LED will appear to the public. Residents who had become comfortable with the warm yellow glow of HPS are not all eager to see their neighborhoods bathed in the same color light that they might park under at the local shopping center.” 

More Cities Turning Off Street Lights: Good For Environment & Taxpayers… But For Bicyclists? (2011 TreeHugger.com). “America’s public spaces and commercial centers are purposely lit all night: rationalized as a weapon in the “war on crime”, but showing, really, a rigid child-like fear of darkness.” 

Streets at night: dark sky tactics to reconnect with the stars (2018 Foreground.com) “New streetlights beam down to reveal streets devoid of activity. The lighting fixtures are part of a $3 million upgrade to the street by Hobart City Council in 2016. If the investment was expected to bring about a street-life renaissance… the “contemporary light fixtures” have had the opposite effect… “There’s a particular street corner where you can see [the difference between] the old and the new lighting. You look toward the old lighting and it’s warmer and the fixtures target the light onto the street. It’s a perfectly safe street. Then you look at the new lighting where the fixtures aren’t targeted, which means that the second, third and fourth storeys of the buildings along the street are all lit up. It’s so bright that nobody wants to be there and you lose the passive surveillance that comes with night activity.” 

The Tragedy Of LED Streetlights: They Don’t Need To Be Such A Nuisance (2016 Forbes) 

Davis, CA LED Streetlight Retrofit (undated, Volt.org). “The complaints were focused on the new fixtures being too bright, producing too much glare and light trespass, increasing skyglow and light pollution, and resulting in potential negative impact on human health and wildlife. When the project was put on hold, 1,400 of the new LED fixtures had already been installed… The City of Davis took the important step of installing a pilot test of the new LED fixtures, but unfortunately did not actively engage broad public feedback to accurately ascertain their opinion until after the process began.” 

Seattle LED Adaptive Lighting Study – NEEA (2014 Northwest Energy Efficiency Alliance). “Contrast of objects, both positive and negative, is a better indicator of visibility than is average luminance level. • Dimming the LED luminaires to fifty percent of IES RP-8 levels did not significantly reduce object detection distance in dry pavement conditions.” 

LED Application Series: Outdoor Area Lighting (2014 Energy.gov). “Illuminance alone does not consider the disabling glare that reduces visibility for the driver. For example, although an IES Type I or Type II distribution may provide the most uniform spread of illuminance with the widest pole spacing along a roadway, the angles of light that allow the very wide spacing are often the angles that subject the driver and pedestrian to disability and discomfort glare.”  

Why your Phoenix streetlights look weird (or are about to) (2018 AZcentral). “Phoenix is in the midst of replacing approximately 100,000 light fixtures. …When the city initially began replacing the fixtures with energy-efficient bulbs in 2015, it used 4,000-Kelvin LED lights, which give off a stark, bright white glow. The public hated them. They were compared to flood lights at a prison or extraterrestrial space saucers. Some people complained that the lights were blinding, unhealthy and blocked views of the night sky. The city found a compromise. It would move forward with the eco-friendly LED lights, but use lower-intensity 2,700-Kelvin fixtures. The 1,500 lights that were already replaced with the bright white lights will be switched to the soft-yellow fixtures as well” [emphasis added]. 

Lunar-resonant streetlights (2016) (interesting idea)

Bulb battle: Some residents hope Phoenix opts for softer LED lights (2016 AZfamily.com) (they eventually succeeded) 

Like It or Not, Chicago’s About to Get a Lot Less Orange (2017 Chicago Magazine)

Skyglow Changes Over Tucson, Arizona, Resulting From A Municipal LED Street Lighting Conversion (2018 Cornell Univ.). “Data were obtained in 2014, before the LED conversion began, and in mid-2017 after approximately 95% of ∼18,000 luminaires was converted. Skyglow differed marginally, and in all cases with valid data changed by <±20%. Over the same period, the city’s upward-directed optical radiance detected from Earth orbit decreased by approximately 7%. While these results are not conclusive, they suggest that LED conversions paired with dimming can reduce skyglow over cities.” 

Chicago dials down LED street lamp intensity — and controversy (2018 EnergyNews.us). “The earlier generations of LED street lamps had temperatures as high as 4,000K or 5,000K. Chicago’s will be 3,000K and able to be dimmed remotely during off-peak times, meeting two of the three AMA guidelines.” 

Darkness design for new motorway (2017 ARUP.cpm). “Their point of departure was not ‘where’ and ‘what type of’ lighting is needed. Rather, they examined the road from the standpoint of darkness. Was lighting even necessary? Taking this into account, safety on the roadway is addressed by providing visual cues through reflection and, where necessary, low light levels. This minimizes light pollution and also visual discomfort glare to drivers. 

Montreal drops disputed LED plan after angry protests (2017 LuxReview.com). ‘After taking note of all the information, notably on the issues of security, light, atmosphere and public health, we chose to move forward with a less intense luminosity,’ the mayor of Montreal, Denis Coderre, commented in a statement. 

To improve health, cities are changing their streetlights (2016 CNN). “In response to recent guidance by the American Medical Association against the use of powerful LED lights, cities such as Phoenix; Lake Worth, Florida; and 25 towns in Connecticut are now opting for street lamps with lower color temperatures, meaning less blue light emission.” 

Are San Francisco’s new LED streetlights too bright? (2017 SF Gate) 

The Future of Outdoor Lighting (2014 American Planning Association) (excellent read!) While the
differences between high CCT (>5000K) LED white light and HPS lighting is often considered purely an
aesthetic issue, it has profound impacts on both visibility and ecology… Blue-rich white light also contributes to light pollution. In 2009, a research study showed that this type of light source scatters light into the atmosphere at a rate two to five times greater than that of currently-used HPS lamps (IDA 2010). The scatter results in increased sky glow, which is the most
easily recognized component of light pollution. An important consequence of this is that if current HPS  4 fixtures are replaced with high-CCT white LED fixtures at the same illumination levels, the result will be a substantial increase in light pollution.

Public Lighting Trends for 2020 (2019). These standards are followed not to ensure that quality lighting is achieved, but primarily to avoid being sued by those who think that lighting equals safety. Even as some standards have evolved to acknowledge the negative impact that glare, light trespass and sky glow can have on visibility and the environment, many cities are still just putting down enough light so they can defend against litigation and to provide the public with a feeling of security.

An Investigation of LED Street Lighting’s Impact on Sky Glow (2017 US Dept of Energy). “Because shorter wavelengths scatter more readily in the Earth’s atmosphere than longer wavelengths, like yellow and red, and because of certain biological sensitivities to shorter wavelengths, a variety of concerns have been raised regarding the potential impact from converting exterior lighting sources with low, short wavelength content, primarily high-pressure sodium (HPS), to broad-spectrum LED… Typical conversion scenarios in the U.S.–an incumbent HPS cobra head product with 2% uplight replaced by each of the LED products listed, at half the light output and 0% uplight… The overall range of results for LED luminaires across most conditions for the near observer is from about 0.4 to 0.8 times the unweighted baseline HPS sky glow, and 0.2 to 1.6 times the scotopically weighted baseline HPS sky glow.” [emphasis added] 

Understanding Light Pollution: Its Environmental Impact and Human Health Implications (2018 Lamps Expo) Although light pollution is a major problem, the situation may not be as bleak as some of the other challenges of modern life. As science examines the issue with increased scrutiny and the general public gains heightened awareness of how it works, more consumers, businesses and lighting producers are taking steps to use lighting more responsibly.

The Six Types of International Dark Sky Designations (undated, DarkSky.org) 

Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting (2011 US Dept of Energy). “Results from the demonstration show energy savings ranging from 26 to 57 percent from all four LED luminaires compared to the baseline HPS luminaire. However, two of the LED systems produced lower average maintained illuminance and a corresponding portion of their respective energy savings must be considered in that context…The cost effectiveness of the FDR Drive installation depends on high electricity rates and deferred costly maintenance… Nevertheless, despite a near certain achievement of energy savings and high potential for improvement in illumination quality, it remains likely at present that a longer-term life-cycle perspective is required to economically justify an investment in solid-state lighting for many roadway lighting applications.” 

Lighten up: NL is getting darker (2018 Dutch News) 

History Of LED’s (undated)

As Light Pollution Spreads, National Parks Become Stargazing Sanctuaries (2018 Undark.org). “In 2017, Condé Nast Traveler declared astrotourism ‘now a thing,’ and a joint University of Michigan/NASA study posited that some 215 million Americans watched that year’s total solar eclipse, nearly double the number who had watched the 2017 Super Bowl.” 

Can We Develop LED Lights that Can Reduce Light Pollution? (2017 GreenTumble.com). “In theory, this should have meant that the light pollution remained at the same level it was before, but that’s not exactly what happened. Instead, what’s happened is the Jevon’s Paradox. This is where new technology increases efficiency, but demand for the products continue to rise regardless. In other words, making better lights didn’t result in us using fewer lights. It just meant people wanted more of them. Overall, the development of LED technology has led to more light pollution, not less.”

Poor Outdoor Lighting 3 What’s the Harm? (undated, Dark Sky Arkansas) 

Blinded by the Light: Addressing the Growing Light Pollution Problem (2014 Texas A&M Journal of Property Law) 

Campus-Wide Networked Adaptive LED Lighting (2014, from UC Davis)

The loss of starry skies: ‘Growing problem’ of light pollution (2018 Star Trbune). “Blue light travels more easily through the atmosphere than the yellow of the old sodium light, causing more skyglow. It can also have serious effects on humans and wildlife.” 

Astronaut’s Playlist: 131 Songs About Stars, Planets, and Space!

OLED—raising lighting to a new level (2012 EDN Network)

Globe at Night Newsletter (March 2019, Glone At Night) 

What Do We Really Know about Light? (2018 Business Wire)

LED Color Characteristics (2016 Energy.gov) 

Night Sky Protection and Restoration in U.S. National Parks (2015 AstronomicalHeritage.net) (PowerPoint presentation) 

Time to Dim the Lights (2019 Pine Tree Watch)

The stars at night, they’re not so bright. Deep in the heart of Tucson(2016 AZ Sonora News)

The Evolutionary Power of Cities and Light (2019 MIT Press)

Western cities try to cut light pollution (2017 High Country News). “That nearly six-decade-old effort seems to have paid off. Today, nighttime images captured by the National Park Service show that Flagstaff emits far less artificial light than other cities of its size.” 

Killing us softly: the perils of light pollution (2019 Foreground.com). “If we recognize the multilayered benefits of reducing light pollution, the next step is to introduce better lighting design into the public realm. ‘At the moment public lighting is not undertaken with a great deal of thought,’ says Adam Carey.” 

Editorial: Just because we can light up the night sky like it’s noontime, doesn’t mean we should (2017 LA Times) 

Glare-Raising: How Much Energy Does Excessive Nighttime Lighting Waste? (2012 Scientific American) 

Starry, Starry Night –The  Dark Night  Skies in Southern Utah (2017 View On Magazine) 

6,000 visible stars light up America’s ‘dark sky’ parks (2015 USA Today) 

The Darkest Town In America (2017 FiveThirtyEight) (good read!)

The Best Smart LED Light Bulbs (2019 TheWireCutter.com) 

Dark Sky Reflector for Large Acorn Globe Light 

Meet The Communities Fighting to Bring Back Their Stars (2018 GIZMODO) (good read)

Conference focus on getting New Zealand to national dark sky status (2019 Timaru Herald) 

The Dark Side, Making war on light pollution (2007 New Yorker)

These Energy-Saving Bulbs Are Making One Pollutant Much Worse (2017 National Geographic)

Our nights are getting brighter, and Earth is paying the price (2019 National Geographic) 

Crowne Plaza trialing circadian lighting at its Atlanta Airport hotel (2019 LEDs Magazine) 

Outdoor site-lighting performance: A comprehensive and quantitative framework for assessing light pollution (2008
Lighting Research & Technology) (behind paywall)

Light Pollution: A Case Study in Framing an Environmental Problem (2017 Journal of Ethics, Policy & Environment) 

Artificially lit surface of Earth at night increasing in radiance and extent (2017 Science Advances). “We use the first-ever calibrated satellite radiometer designed for night lights to show that from 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries. These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.” 

Potential Environmental Impacts from the Metals in Incandescent, Compact Fluorescent Lamp (CFL), and Light-Emitting Diode (LED) Bulbs (2013 Environmental Science Technology). “The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of the bulbs, the CFLs and LEDs have 3–26 and 2–3 times higher potential impacts than the incandescent bulb, respectively.” 

Light reflected off fresh snow can outshine the moon (2019 Journal of Imaging). “A blanket of new snow could increase the amount of light in the sky above a suburban area by as much as 33% on a clear night, the team reports this month in the Journal of Imaging. When the sky was cloudy, the brightness rose almost 200%, more than twice as bright as the full moon.”

Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems (2011 PLOS ONE). “The sky glow caused by artificial lighting from urban areas disrupts this natural cycle, and has been shown to impact the behavior of organisms, even many kilometers away from the light sources… We show that cloud coverage dramatically amplifies the sky luminance, by a factor of 10.1 for one location inside of Berlin and by a factor of 2.8 at 32 km from the city center. We also show that inside of the city overcast nights are brighter than clear rural moonlit nights, by a factor of 4.1.”

VIIRS night-time lights (2017 International Journal of Remote Sensing) 

Candlelight-style organic LEDs: a safe lighting source after dusk (2013 SPIE.org) “Frequent exposure to bluish light at night, and the corresponding reduced MLT levels, is associated with an increased risk of breast, colorectal, and prostate cancers.” 

The Dark Side of Light: A Transdisciplinary Research Agenda for Light Pollution Policy (2010 Ecology and Society). “Unless managing darkness becomes an integral part of future conservation and lighting policies, modern society may run into a global self-experiment with unpredictable outcomes.” 

Artificially lit surface of Earth at night increasing in radiance and extent (2017 Science Advances). “A central aim of the “lighting revolution” (the transition to solid-state lighting technology) is decreased energy consumption. This could be undermined by a rebound effect of increased use in response to lowered cost of light. We use the first-ever calibrated satellite radiometer designed for night lights to show that from 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries. These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.” 

The Dark Side of Light: A Transdisciplinary Research Agenda for Light Pollution Policy (2010 Ecology and Society). “Given the dramatic increase in artificial light at night (0 – 20% per year, depending on geographic region), we see an urgent need for light pollution policies that go beyond energy efficiency to include human well-being, the structure and functioning of ecosystems, and inter-related socioeconomic consequences. Unless managing darkness becomes an integral part of future conservation and lighting policies, modern society may run into a global self-experiment with unpredictable outcomes.”

The first World Atlas of the artificial night sky brightness (2001 Royal Astronomical Society). “We present the first World Atlas of the zenith artificial night sky brightness at sea level. Based on radiance-calibrated high-resolution DMSP satellite data and on accurate modelling of light propagation in the atmosphere, it provides a nearly global picture of how mankind is proceeding to envelop itself in a luminous fog. Comparing the Atlas with the United States Department of Energy (DOE) population density data base, we determined the fraction of population who are living under a sky of given brightness. About two-thirds of the World population and 99 per cent of the population in the United States (excluding Alaska and Hawaii) and European Union live in areas where the night sky is above the threshold set for polluted status. Assuming average eye functionality, about one-fifth of the World population, more than two-thirds of the United States population and more than one half of the European Union population have already lost naked eye visibility of the Milky Way. Finally, about one-tenth of the World population, more than 40 per cent of the United States population and one sixth of the European Union population no longer view the heavens with the eye adapted to night vision, because of the sky brightness.” 

Lighting Professionals versus Light Pollution Experts? Investigating Views on an Emerging Environmental Concern (2019 Sustainability). “Although lighting professionals are often critical of calling light ‘pollution’, they increasingly acknowledge the problem and are beginning to act accordingly.” 

Sky brightness levels before and after the creation of the first International Dark Sky Reserve, Mont-Megantic Observatory, Quebec, Canada (2014 Journal of Quantitative Spectroscopy and Radiative Transfer). “…The results show that replacing light fixtures within a 25 km radius around the MMO with cut-off High Pressure Sodium devices and reducing the total installed radiant power to ~40% of its initial level are very efficient ways of reducing artificial sky brightness. The artificial sky brightness reduction at zenith observed after the establishment of the IDSR was ~50% in the 546 nm mercury spectral line, while the reduction obtained in the 569 nm sodium line was ~30%.  A large part of that reduction can be associated to the reduction in radiant power.” 

Mont-Mégantic (Québec) (2007 DarkSky.org). “The process that led to the IDA designation contributed to the development of a new regional expertise in outdoor lighting management. As a result, the reserve’s 34 municipalities developed outdoor lighting regulations that have contributed to the control and limited growth of area light pollution, which had doubled during the preceding 20 years. Approximately 2,500 light fixtures were replaced, resulting in a 25 percent reduction of area light pollution and a reduction in energy consumption of some 1.3 gigawatt-hours per year.” 

Consumers sour on milk exposed to LED light (2016 Cornell Univ.). “Cornell researchers in the Department of Food Science found exposure to light-emitting diode (LED) sources for even a few hours degrades the perceived quality of milk more so than the microbial content that naturally accumulates over time. Their study determined milk remained at high-quality for two weeks when shielded from LED exposure, and consumers overwhelmingly preferred the older, shielded milk over fresh milk stored in a typical container that had been exposed to LED light for as little as four hours.” 

The Problems of Light Pollution – Overview (undated, FL Atlantic Univ.) 

Dark Sky Residential Lighting Products (2019 Flagstaff Dark Skies) 

The Dark Side of Light (2019 The Atlantic). “Artificial light changes animal migration and reproduction, tree leaf growth, bird nesting and fledging, pollination, human sleep, and much more. It even affects the spread of diseases.” 

The Lost LED Revolution: Light Pollution Is Increasing (2017 Sky & Telescope). …The DNB is insensitive to wavelengths below 500 nanometers — blue light, which the atmosphere scatters more than other visible wavelengths. Unfortunately, many popular LED lights peak at these wavelengths. It doesn’t have to be this way. “One of the really huge advantages of LEDs is that it’s possible to make very many different colors,” Kyba insists. “Cities can buy lamps that are not white, that have this blue component completely removed.” However these “PC Amber” or “True Amber” lights are so far used almost exclusively in designated dark-sky places. Nevertheless, Kyba and his colleagues remain open to working with cities, local governments, and industry partners to reverse this trend: “The real dream is that we have great vision on the streets, never really experience an uncomfortably dark place inside of a city, but because the light is used much more efficiently, would have more stars to see in the sky.” 

OPINION of the French Agency for Food, Environmental and Occupational Health & Safety on the “effects on human health and the environment (fauna and flora) of systems using light-emitting diodes (LEDs)”  (2019 French Govt.) (excellent, thorough and up to date!)

The Switch to Outdoor LED Lighting Has Completely Backfired (2017 Gizmodo.com). “This study is important because it validates with data two things we have suspected: that the rate of growth of light pollution continues upward on a worldwide scale, and that the migration of outdoor lighting from older technologies to LED isn’t having the anticipated benefit in terms of global reductions in energy usage,” John Barentine, the resident physical scientist for the International Dark-Sky Association, told Gizmodo. “The latter point is especially important because a number of governments have been convinced to convert their outdoor lighting to LED on the basis of promised reductions in energy usage.” 

Streetlight Fight in Rome: Golden Glow vs. Harsh LED (2017 NY Times) 

New LED lights threaten health, environment (2017, letter to the editor). “Turns out that a single streetlight filtering in through typical bedroom curtains inhibits essential melatonin production. Why would Chicago shut off melatonin levels of millions of its citizens causing increased risk of breast, prostate, colon, pancreatic and some lymphoma cancers; type 2 diabetes and obesity; memory, sleep and mood disorders; heart disease and more—including rendering some chemotheraphy drugs like Tamoxifen ineffective?” 

‘It’s early morning all night long’: Halifax residents revolt over LED street lights (2017 CBC) 

Melatonin: Nature’s most versatile biological signal? (2006 FEBS Journal). “Melatonin is a ubiquitous molecule and widely distributed in nature, with functional activity occurring in unicellular organisms, plants, fungi and animals… Synthesis of melatonin also occurs in other areas of the body, including the retina, the gastrointestinal tract, skin, bone marrow and in lymphocytes, from which it may influence other physiological functions through paracrine signaling. Melatonin has also been extracted from the seeds and leaves of a number of plants and its concentration in some of this material is several orders of magnitude higher than its night‐time plasma value in humans. Melatonin participates in diverse physiological functions. In addition to its timekeeping functions, melatonin is an effective antioxidant which scavenges free radicals and up‐regulates several antioxidant enzymes.” 

Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights (2001 Physiology.org). “Subjective sleep quality diminished. Polysomnography revealed more wakefulness and less slow-wave sleep during the final third of sleep episodes. Administration of melatonin (0.3 mg) on alternate nights did not improve sleep. After return to earth, rapid eye movement (REM) sleep was markedly increased. Crewmembers on these flights experienced circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and postflight changes in REM sleep.” 

The dark side of light at night: physiological, epidemiological, and ecological consequences [old but good] (2007). “The increasing prevalence of exposure to light at night has significant social, ecological, behavioral, and health consequences that are only now becoming apparent… Should exposure to light be regulated as endocrine disrupting compounds in the environment? Proposals have been put forth to decrease levels of urban sky glow through light shields, reduction in the number of lights, as well as through an adjustment of the color spectrum produced by external lighting towards low‐level red lighting and away from the highly disruptive high‐energy blue lighting. It is clear that increasing levels of urban sky glow can have serious medical and ecological repercussions (Fig. 1). Additionally, elevated numbers of night shifts worked could result in large‐scale incidences of metabolic disorders, immunosuppression, oxidative stress, and cancer” (emphasis added). 

‘Dark Sky-friendly’ lighting ordinance adopted by Ridgway Town Council (2019 Telluride News). Inky-black nights and luminous starscapes are precious commodities in this hyper-illuminated world, and an increasing number of western communities are racing to preserve the dark by becoming Dark Sky communities… Out of “all of the Planning Commission and Town Council meetings that have discussed IDA Dark Sky designation, no one from the business community, or any private citizens, have made any negative comments” about it. 

Why I adore the night, by Jeanette Winterson (2009 The Guardian) 

Searching for the light in the dark (2019 The Edge Markets). “But where I think the biggest negative consequence of the dying of the dark is slightly more abstract, which is losing our sense of wonder and awe from our night sky. For pretty much all of human history, our entire species has collectively gazed at the night sky in deep wonder. It is perhaps no coincidence that astronomy is the oldest science.” 

dimm LIGHT [German company’s product to retrofit new or existing streetlight systems] (undated). “With LED systems you can reduce power consumption, but hardly relieve the budget. Because high follow-up costs after wear of the bulbs often lead to the neutralization of previous savings. With our patented, award-winning dimmLIGHT solution “made in Saxony-Anhalt”, for example, energy consumption and the costs of street lighting in over 350 municipalities have been halved for ten years.”  

Blue boxes save electricity [newspaper story about dimmLIGHT company, above] (2019). “Electricity consumption can be reduced steplessly by up to 67 percent during low-traffic, low-night hours via individually definable programming. On the screen of the small computer can be tracked how dimming shut down high and energy performance. It takes a few minutes for the lamps to glow less brightly – but this is hardly noticeable to the beholder. He has no comparison, because all neighboring points of light appear equally strong. In the city budget, however, the dimming technique of the mayor will make clearly noticeable. Every year, energy costs and carbon dioxide emissions are expected to fall by around half. Although first with the 87 – out of a total of 350 – lamps in the commercial area, which provide about 12,400 watts in a quarter of the area for light. Dimming means an annual consumption of 27,000 kilowatt hours and a saving of around 6,000 euros for the city. After three and a half years, the investment should have amortized, says Mayor Ritter. And that the city would gradually change the other lamps. The total energy costs for the urban area amount to around 105,000 euros annually.”

Demonstration Assessment of Light-Emitting Diode (LED) Street Lighting (2009 Energy.gov) (Portland, OR, replaced 2100K HPS with 5120K LED). “Much of the associated energy savings (55%) supporting these [LED] payback periods, however, were achieved by reducing average horizontal photopic illuminance a similar amount (53%).” 

Seattle LED Adaptive Lighting Study – NEEA (2014 Northwest Energy Efficiency Alliance). “Luminance does not exhibit a correlation to detection distance; the two HPS luminaires and the 5000K LED provided greater levels of luminance than did either of the 4100K LEDs (symmetric or asymmetric) but did not show a related increase in the object visibility. This demonstrates that the primary indication of visibility is contrast and that a reduced luminance level with equivalent contrast may provide equivalent or better detection distances… The results of the written evaluation indicate a preference for the incumbent HPS streetlights, while still showing acceptance of the LED luminaires.

Advanced Street Lighting Technologies Assessment Project – City of San Diego (2010 City of San Diego). “…It may be appropriate to consider other lighting technologies in addition to light sources for any city-wide street light technology replacement project. One opportunity worth consideration is adaptive street lighting controls which adapts the lighting output of individual or system-wide street lighting to its environment by dimming. The implementation of these controls can improve energy savings, reduce maintenance, and reduce light pollution.” 

LED Streetlights and the Environmental – Environmental Issues (undated slide program) 

Outdoor Lighting Retrofits: A guide for the National Park Service and other federal agencies (2014 Univ. CA Davis) 

It’s Darker in Big Bend National Park, Thanks to a Light Reduction Project in the Chisos Basin (2010 Nat Parks Traveller). “The new LED fixtures are rated at less than 1 watt each and replace 60 watt incandescent and fluorescent lamps. That adds up to some impressive results: a 98% reduction in wattage, energy consumption, and greenhouse emissions. Park budgets are always tight, and this project will provide some welcome cost savings. It’s estimated that annual energy bills for the equipment that was replaced will drop from $3,292 to $164.” 

Dark Skies Over Torrey [example of a fundraiser that paid for new lights for small Utah town] (2017 IOBY.org) 

Light pollution controls make Torrey the first ‘dark sky’ town in Utah (2019 Salt Lake Tribune). “Torrey residents and organizations raised about $20,000 last year to replace bulbs in streetlights and in outdoor lights at some prominent businesses. A 2016 Missouri State University study reviewed national park visitor surveys and spending and found that up to $2.5 billion in tourism spending at parks on the Colorado Plateau could be gained or lost with dark skies.” 

Colorado Towns Work to Preserve a Diminishing Resource: Darkness (2018 NY Times). “You can’t just go up to someone and say, you’ve got a bad light, and legislate the problem away,” he said. “People resist that, especially in Colorado.” 

How a Colorado valley became the center of the Milky Way (2016 CO Independent). It hasn’t always been easy to persuade locals to get on board. At first, Bradburn says, the Dark Sky members got a little over-enthusiastic about telling people they had to change their lights to preserve the night sky. Their “light police” attitude didn’t sit well among everyone in the community, which has been the home of family ranches going back 150 years… It was Jack’s idea to start raising money to change out the streetlights, and that has made all the difference. For those who haven’t been able to afford it, the homegrown group of stargazers raises money to pay for the lights and other Dark Sky-compliant fixtures. “We need to be advocates and educators to maintain our Dark Sky heritage,” Bradburn says. “We don’t tell the neighbors to cover their lights,” but if they’re willing to change, the stargazers will make it happen. It cost the group about $10,000 to convert all the streetlights in Silver Cliff. 

Detroit’s LED streetlights going dark after a few years (2019 Detroit News). “The Public Lighting Authority in its complaint against Leotek Electronics USA notes that upward of 20,000 LED lights are “prematurely dimming and burning out…” 

Detroit Sues Lighting Manufacturer Over Failed Street Lights (2019 Lighted Magazine)

Detroit finishing up replacing all defective streetlights (2019 Detroit News). “The replacement, which is expected to cost between $7 million to $8 million, is ahead of the lighting authority’s goal earlier this year to swap out fixtures on 19,500 lights by the end of the year. The authority, which is funding the project, is seeking reimbursement from the lighting manufacturer, California-based Leotek Electronics USA.” 

The unfortunate side effect of LED lighting (2017 The Verge) 

5 Popular Myths About LED Streetlights (2016 DarkSky.org) “Fun fact: The surface brightness of commercial white LEDs is now about 1/30 the surface brightness of the Sun, and surface brightness doesn’t scale according to the viewer’s distance from the source.” 

A Mysterious Patch Of Light Shows Up In The North Dakota Dark (2013 NPR) 

How Flagstaff, Arizona, switched to LEDs without giving astronomers a headache (2019 ars technica). “I see this wherever I go in my travels. By default, cities just put up, you know, 3,000 degrees CCT white, sometimes 4,000, which is this blue light. Just lumen for lumen [that] will create two-and-a-half to three times the skyglow of a high-pressure sodium system and, like, six times the skyglow of a low-pressure sodium system.” 

LED bulb implementation involves more than energy efficiency for local college (2019 ABC57.com). “…LED lights are becoming extremely popular for good reasons, but in order to create an ideal situation for things like studying and learning as opposed to sleeping, careful consideration should be taken when choosing the light bulb’s color temperature, which is measured in degree Kelvin. “What impacts us the way that we as humans perceive, physiologically, and experience light, are things like the lumen level, the brightness of the light, and the color temperature,” Weger said. “Basically our bodies have evolved and we’re used to being in tune with the sun.” 

Measuring and using light in the melanopsin age (2014 Science Direct) “Light is a potent stimulus for regulating circadian, hormonal, and behavioral systems. In addition, light therapy is effective for certain affective disorders, sleep problems, and circadian rhythm disruption. These biological and behavioral effects of light are influenced by a distinct photoreceptor in the eye, melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), in addition to conventional rods and cones. We summarize the neurophysiology of this newly described sensory pathway and consider implications for the measurement, production, and application of light. A new light-measurement strategy taking account of the complex photoreceptive inputs to these non-visual responses is proposed for use by researchers, and simple suggestions for artificial/architectural lighting are provided for regulatory authorities, lighting manufacturers, designers, and engineers.”

Montreal drops disputed LED plan after angry protests (2017 LUX Magazine) The City of Montreal has dropped plans to replace 132,000 streetlights with 4000K LED luminaires after angry protests prompted a change of heart in city hall.

EnGoPlanet lights up Las Vegas using Smart Street Lights (2016 Balken Green Energy News)

Let there be dark: the battle to save our sky from light pollution (2019 The Guardian) “These days, people erect two or three of these absolutely searingly bright white LEDs. We don’t realise the profound effects it’s having, putting up light domes over small farms or villages – places that had no light dome before – and transforming the night-time scene from something quite beautiful into something numbingly banal.”

Wondering why car headlights are so painfully blinding? Well it could be down to your age (2017 Daily Mail). “The main problem is light scatter. The eye’s lens and cornea are not perfectly clear, so when bright light is shone through them, some gets scattered around the inside of the eye, making images blurred or blank… ‘At night your pupil opens wider to let in more light, and when your eye meets a headlamp you get more scatter and can’t see.’ 

The dangers of modern headlights (2019 SAMotor). “Known as High Intensity Discharge lights (HIDs) or xenons, these headlights are about 3 times brighter than traditional headlights and designed to give drivers a clearer view of the road… And according to Optometry Australia, road users are more heavily affected as they age. The not-for-profit organisation says glare generally affects older drivers more due to their ageing cornea… In fact, drivers around the age of 40 and older often start to complain about increased sensitivity to bright lights and visual discomfort, particularly while driving at night. That said, these luminescent lights can also have the opposite effect, as road users may find themselves temporarily blinded if they’re too bright.”

How to Avoid Glare From Headlights (2019). “Glare reduces a driver’s visibility and increases the risk of an accident, especially on two lane highways… It affects you, not only while the light is visible, but also after the glare is no longer in your field of view. Why is this? Well, after the vehicle has passed by, it takes some time for the pupil to readjust to the less intense light. Older drivers, impaired drivers, and drivers in poor physical condition usually find glare more difficult to handle since it takes longer for their eyes to recover. The brighter the headlights, the greater the glare is, the less you can see of the road ahead and the longer it will take for your eyes to recover.”

Lightmare [bright lights on vehicles] (undated). “Our organization has been formed to fight the growing road safety issue of blinding lights which diminish a driver’s ability to perceive hazards.”