Anthropogenic noise and light pollution decrease the repeatability of activity patterns and dampen expression of chronotypes in a free-living songbird.

Anthropogenic environmental change is introducing a suite of novel disturbance factors, which can have wide-ranging effects on mean behavior and behavioral repeatability. For example, exposure to sensory pollutants, such as anthropogenic noise and artificial light at night (ALAN), may affect consistent and repeatable individual-level timing of daily activity, which is referred to as chronotypes. Although chronotypes have been increasingly documented in wild animal populations and may affect fitness, evidence for long-term stability across life-history stages and seasons is notably lacking. Furthermore, how multiple anthropogenic stressors may interact to erode or magnify the expression of chronotypes remains unclear. We tested for existence of chronotypes across life-history stages and seasons in suburban female great tits (Parus major), using emergence time from nest boxes in the morning as a proxy for activity onset. We then examined joint effects of noise pollution and ALAN on expression of chronotypes, and tested for effects of noise, ALAN, and weather conditions on mean emergence time. We found repeatability of daily activity patterns (emergence times) across life-history stages and seasons, providing evidence of chronotypes, as well as interactive effects of anthropogenic disturbance factors and weather conditions on population mean behavior. Furthermore, across-season repeatability of emergence times was approximately double in magnitude in low light and low noise conditions, relative to in conditions with higher light and/or noise pollution. Thus, joint exposure to these sensory pollutants tends to erode expression of chronotypes. This effect was driven by higher among-individual variance in the relatively undisturbed environment and collapse of this variance in the more disturbed environments. Decreased repeatability in environments with high disturbance levels may reduce potential for behavioral traits, such as chronotype, to be the target of selection and limit adaptability.

Outdoor nighttime light exposure (light pollution) is associated with Alzheimer's disease.

Introduction: Alzheimer's disease (AD) prevalence has increased in the last century which can be attributed to increased lifespan, but environment is also important. Exposure to artificial light at night is one environmental factor that may influence AD. Methods: This study evaluated the relationship between outdoor nighttime light exposure and AD prevalence in the United States using satellite acquired outdoor nighttime light intensity and Medicare data. Results: Higher outdoor nighttime light was associated with higher prevalence of AD. While atrial fibrillation, diabetes, hyperlipidemia, hypertension, and stroke were associated more strongly with AD prevalence than nighttime light intensity, nighttime light was more strongly associated with AD prevalence than alcohol abuse, chronic kidney disease, depression, heart failure, and obesity. Startlingly, nighttime light exposure more strongly associated with AD prevalence in those under the age of 65 than any other disease factor examined. Discussion: These data suggest light exposure at night may influence AD, but additional studies are needed.

Brominated Flame Retardant HBCD and Artificial Light at Night Synergically Caused Visual Disorder and Sleep Difficulty in Zebrafish Larvae.

Sleep difficulty is a widespread health concern exacerbated by factors such as light and chemical pollution. Artificial light at night (ALAN) can disrupt natural sleep-wake cycles, whereas chemical pollutants can impair sleep-related processes. The prevalence of ALAN increases the health risk of coexposure, yet it has not gained sufficient attention. Meanwhile, visual inputs are important for sleep regulation, especially the non-image-forming circadian visual system centered around melanopsin. This study evaluated the light perception ability and sleep performance of zebrafish larvae exposed to flame retardant hexabromocyclododecanes (HBCDs) at environmentally relevant concentrations (2.5 and 25 µg/L) and to cotreatment of HBCD and ALAN. HBCD induced a longer sleep latency of 34.59 min under 25 µg/L (p < 0.01) versus control (26.04 min). The situation was intensified by coexposure with low-level ALAN (10 lx) to 48.04 min. Similar synergic effects were observed for upregulations of Xenopus-related melanopsin genes and downregulations of the melatonin synthesis gene aanat2, suggesting a melanopsin-aanat2-sleep retina-brain pathway. Image-forming opsins (opn1sw1 and opn1sw2) were also activated by HBCD to 1.29-1.53-fold (p < 0.05), together with elevated retina glutamate, but without synergic effects. Collectively, we found that HBCD and ALAN coexposure caused synergic effects on the non-image-forming visual system and caused sleep difficulty in zebrafish larvae.

Sleep problems mediate the association between outdoor nighttime light and symptoms of depression and anxiety: A cross-sectional, multi-city study in Bulgaria.

BACKGROUND: Nighttime light is a growing anthropogenic health threat, particularly in urban areas. Limited evidence suggests that exposure to outdoor artificial light at night (ALAN) may be associated with people's mental health by disrupting sleep-wake cycles. AIMS: We assessed 1) the association between ALAN exposure and adults' symptoms of depression and anxiety, 2) whether the association was modified by sex, age, and income, and 3) the mediating role of sleep problems. METHODS: We obtained cross-sectional data from 4,068 adults from the five largest Bulgarian cities. Depression and anxiety symptoms were measured using the 4-item Patient Health Questionnaire (PHQ-4). Sleep problems were self-reported based on three items. Outdoor ALAN at residential addresses was assessed using annual radiance levels obtained from satellite imagery. Regression models were adjusted for person-level characteristics, green space, and nitrogen dioxide (NO2). We also assessed effect modification by sex, age, and income. Using mediation analyses, we tested sleep problems as a mediator of the ALAN-PHQ-4 association. RESULTS: Greater ALAN exposure in the fully adjusted model was marginally associated with higher PHQ-4 scores. We observed no effect modification. The mediator, sleep problems, was also positively associated with ALAN. The mediation of sleep problems was significantly positive. While the direct association was null, the total ALAN association was marginally and positively associated with PHQ-4 scores. CONCLUSIONS: Our findings suggest a positive association between outdoor nighttime light pollution and mental health. Poor sleep quality is a possible pathway relating ALAN exposure to mental health. Considering the increasing ubiquity and intensity of urban nighttime illumination, light pollution-reducing policies may provide significant health benefits for urban populations.

Outdoor light at night, air pollution and risk of incident type 2 diabetes.

BACKGROUND: Air pollution and outdoor light at night (LAN) have been reported to be related to type 2 diabetes (T2D). However, their interaction with risk of T2D remains uncertain. Therefore, our study aimed to explore the relationship between outdoor LAN, air pollution and incident T2D. METHODS: Our study included a cohort of 24,147 subjects recruited from 2015 to 2018 in Ningbo, China. Land use regression models were used to evaluate particulate matter with a diameter ≤2.5 µm (PM2.5), ≤10 µm (PM10) and nitrogen dioxide (NO2). Satellite images data with a spatial resolution of 500m was used to estimate outdoor LAN levels. T2D new cases were identified by medical records based on health information system. Cox proportional hazards models were used to estimate Hazard ratios (HRs) and 95% confidence intervals (CIs). Moreover, we investigated the multiplicative and additive interactions between air pollution and outdoor LAN. RESULTS: During 108,908 person-years of follow-up period, 1016 T2D incident cases were identified. The HRs (95% CIs) were 1.22 (1.15, 1.30) for outdoor LAN, 1.20 (1.00, 1.45) for PM2.5, 1.23 (1.11, 1.35) for PM10 and 1.19 (1.04, 1.37) for NO2 in every interquartile range increase, respectively. Furthermore, significant interactions were observed between outdoor LAN and NO2. CONCLUSIONS: Our findings indicated that air pollution and outdoor LAN were positively associated with T2D. Moreover, we observed an interaction between outdoor LAN and NO2 suggesting that stronger associations for outdoor LAN and T2D in areas with higher levels of NO2, and for NO2 and T2D in areas with higher levels of outdoor LAN.

Nobiletin, an activator of the pyruvate kinase isozyme M1/M2 protein, upregulated the glycolytic signalling pathway and alleviated depressive-like behaviour caused by artificial light exposure at night in zebrafish.

We established a zebrafish model of depression-like behaviour induced by exposure to artificial light at night (ALAN) and found that nobiletin (NOB) alleviated depression-like behaviour. Subsequently, based on the results of a 24-h free movement assay, clock gene expression and brain tissue transcriptome sequencing, the glycolysis signalling pathway was identified as a potential target through which NOB exerted antidepressant effects. Using the ALAN zebrafish model, we found that supplementation with exogenous L-lactic acid alleviated depressive-like behaviour. Molecular docking and molecular dynamics simulations revealed an inter-molecular interaction between NOB and the pyruvate kinase isozyme M1/M2 (PKM2) protein. We then used compound 3 k to construct a zebrafish model in which PKM2 was inhibited. Our analysis of this model suggested that NOB alleviated depression-like behaviour via inhibition of PKM2. In summary, NOB alleviated depressive-like behaviour induced by ALAN in zebrafish via targeting of PKM2 and activation of the glycolytic signalling pathway.

Outdoor light at night is a modifiable environmental factor for metabolic syndrome: The 33 Communities Chinese Health Study (33CCHS).

Metabolic syndrome (MetS) is a significant public health problem and presents an escalating clinical challenge globally. To combat this problem effectively, urgent measures including identify some modifiable environmental factors are necessary. Outdoor artificial light at night (LAN) exposure garnered much attention due to its impact on circadian rhythms and metabolic process. However, epidemiological evidence on the association between outdoor LAN exposure and MetS remains limited. To determine the relationship between outdoor LAN exposure and MetS, 15,477 adults participated the 33 Communities Chinese Health Study (33CCHS) in 2009 were evaluated. Annual levels of outdoor LAN exposure at participants' residential addresses were assessed using satellite data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Generalized linear mixed effect models were utilized to assess the association of LAN exposure with MetS and its components, including elevated waist circumference (WC), triglycerides (TG), blood pressure (BP), fasting blood glucose (FBG), and reduced high-density lipoprotein cholesterol (HDL-C). Effect modification by various social demographic and behavior factors was also examined. Overall, 4701 (30.37 %) participants were defined as MetS. The LAN exposure ranged from 6.03 to 175.00 nW/cm2/sr. The adjusted odds ratio (OR) of MetS each quartile increment of LAN exposure were 1.43 (95 % CI: 1.21-1.69), 1.44 (95 % CI: 1.19-1.74) and 1.52 (95 % CI: 1.11-2.08), respectively from Q2-Q4. Similar adverse associations were also found for the components of MetS, especially for elevated BP, TG and FBG. Interaction analyses indicated that the above associations were stronger in participants without habitual exercise compared with those with habitual exercise (e.g. OR were 1.52 [95 % CI: 1.28-1.82] vs. 1.27 [95 % CI, 1.04-1.55], P-interaction = 0.042 for MetS). These findings suggest that long-term exposure to LAN can have a significant deleterious effect on MetS, potentially making LAN an important modifiable environmental factor to target in future preventive strategies.

Behavioural and transgenerational effects of artificial light at night (ALAN) of varying spectral compositions in zebrafish (Danio rerio).

Artificial light at night (ALAN) can disrupt the natural behaviour, physiology, and circadian rhythms of organisms exposed to it, and therefore presents a significant and widespread ecological concern. ALAN typically comprises a wide range of wavelengths, and different wavelengths have different effects on circadian clocks. In the animals investigated thus far, short and middle wavelengths are intensely involved in synchronisation and entrainment, but we still have a poor understanding of how different wavelengths might affect behaviour when animals are exposed to ALAN, in particular whether some wavelengths are disproportionally detrimental. This experiment examined the direct and transgenerational effects of 10 different wavelength treatments of ALAN on behaviour in zebrafish (Danio rerio), a diurnally active model organism. Across a 10-day period, female zebrafish were exposed to either a monochromatic wavelength, white light ALAN, or to a control treatment, and the individual impacts of each treatment on locomotion and anxiety-like behaviours were examined both for solitary fish and fish in groups. We found the strongest impact at short wavelengths (365 to 470 nm), with individuals and groups of zebrafish showing more anxiety-like behaviour after fewer nights of ALAN exposure relative to the other wavelengths. Furthermore, F1 offspring born from ALAN-exposed mothers displayed less frequent movement and shorter movement distances despite never being exposed to ALAN themselves, regardless of the spectral treatment. Our results highlight both the specific and broad-spectrum potential for ALAN to cause disruption to locomotion in adult zebrafish and their offspring.

Exposure to Light at Night and Risk of Cancer: A Systematic Review, Meta-Analysis, and Data Synthesis.

BACKGROUND: Emerging interest surrounds the role of environmental factors, notably exposure to light at night (LAN), as a potential cause of cancer. The aim of this study was to conduct a systematic review and, if possible, meta-analysis of observational studies on LAN and cancer risk of multiple types. METHODS: A systematic literature search in PubMed, Web of Science, and Embase, spanning from inception to May 2023, was conducted. Studies focusing on the association between LAN exposure and cancer risk in adult populations were included. We used random effects models to calculate pooled risk estimates (RR) and 95% confidence intervals (CI). We assessed study quality using the Risk of Bias in Non-randomized Studies of Interventions. RESULTS: Among 8492 initially identified studies, 26 met the inclusion criteria (13 were case-control and 13 were cohort studies). These studies were published from 2001 to 2023 and assessed diverse cancer types in North America, Asia, Europe, and Australia. Except for breast cancer, there was a paucity of site-specific cancer studies. In the meta-analysis of 19 breast cancer studies, higher exposure to indoor (summary RR, 1.08; 95% CI 1.01-1.15) and outdoor (summary RR, 1.10; 95% CI, 1.04-1.15) LAN were associated with increased risk. After excluding one low-quality study, the results were unchanged. CONCLUSIONS: We found a positive association between LAN exposure and breast cancer risk in women. However, data are lacking for other cancer types, and further studies are required to better understand the role of LAN on cancer.

Assessment of indoor light-at-night exposure in children and adolescents during schooldays and weekends.

Light-At-Night (LAN) is increasingly recognized and may has adverse health effects on children and adolescents, yet few studies have reported objective indoor LAN exposure levels for children and adolescents. In this study, we measured the indoor LAN exposure levels and duration among 897 children and adolescents aged 6-14 in Beijing, China, using portable photometers during both school days and weekends. Results indicate that the median indoor LAN exposure from 9:00 p.m. to 7:00 a.m. was 5.1 lx, with 31.8% of the subjects experiencing an average exposure above 10 lx. Additionally, from the perspective of cumulative high exposure duration, children and adolescents were exposed to more than 10 lx for approximately 64 min from 9:00 p.m. to 7:00 a.m. During the entire nighttime (from self-reported bedtime to wake-up time), the median exposure was 2.1 lx, with 16.6% averaging exposures above 10 lx. Exposure levels were significantly higher on weekends than on schooldays. Both girls and upper-grade students had higher levels of exposure and longer durations of high exposure. Girls in grade 7 (OR:2.56, 95%CI: 1.68-3.88) experienced the highest LAN exposure in our subjects compared to boys in grade 1-4. Our findings underscore the importance of promoting healthy light exposure behaviors among children and adolescents and reducing their light exposure environments to mitigate the potential health impacts of LAN.

Insights into the Effect of Light Pollution on Mental Health: Focus on Affective Disorders-A Narrative Review.

The presence of artificial light at night has emerged as an anthropogenic stressor in recent years. Various sources of light pollution have been shown to affect circadian physiology with serious consequences for metabolic pathways, possibly disrupting pineal melatonin production with multiple adverse health effects. The suppression of melatonin at night may also affect human mental health and contribute to the development or exacerbation of psychiatric disorders in vulnerable individuals. Due to the high burden of circadian disruption in affective disorders, it has been hypothesized that light pollution impacts mental health, mainly affecting mood regulation. Hence, the aim of this review was to critically summarize the evidence on the effects of light pollution on mood symptoms, with a particular focus on the role of circadian rhythms in mediating this relationship. We conducted a narrative review of the literature in the PubMed, Scopus, and Web of Science datasets. After the screening process, eighteen papers were eligible for inclusion. The results clearly indicate a link between light pollution and the development of affective symptoms, with a central role of sleep disturbances in the emergence of mood alterations. Risk perception also represents a crucial topic, possibly modulating the development of affective symptoms in response to light pollution. The results of this review should encourage a multidisciplinary approach to the design of healthier environments, including lighting conditions among the key determinants of human mental health.

Sociodemographic inequalities in residential nighttime light pollution in urban Bulgaria: An environmental justice analysis.

INTRODUCTION: Outdoor nighttime light (NTL) is a potential anthropogenic stressor in urban settings. While ecological studies have identified outdoor NTL exposure disparities, uncertainties remain about disparities in individual exposure levels, particularly in Europe. AIM: To assess whether some populations are disproportionately affected by outdoor NTL at their residences in urban Bulgaria. METHODS: We analyzed 2023 data from a representative cross-sectional survey of 4,270 adults from the five largest Bulgarian cities. Respondents' annual exposures to outdoor artificial nighttime luminance were measured using satellite imagery and assigned at their places of residence. We calculated the Gini coefficient as a descriptive NTL inequality measure. Associations between respondents' NTL exposure levels and sociodemographic characteristics were assessed by estimating quantile mixed regression models. Stratified regressions were fitted by gender and for each city. RESULTS: We found moderate distributive NTL inequalities, as indicated by a 0.214 Gini coefficient. Regression analyses found associations between greater NTL exposure and higher educational attainment. Respondents with incomes perceived as moderate experienced less NTL exposure at the 0.5 and 0.8 quantiles, while unemployed respondents experienced lower exposure at the 0.2 and 0.5 quantiles. We observed null associations for the elderly and non-Bulgarian ethnicities. Regardless of the quantile, greater population density was associated with higher NTL levels. Stratification by sex did not yield substantial differences in the associations. We observed notable city-specific heterogeneities in the associations, with differences in the magnitudes and directions of the associations and the NTL quantiles. CONCLUSIONS: NTL exposures appeared to embody an environmental injustice dimension in Bulgaria. Our findings suggest that some sociodemographic populations experience higher exposure levels to NTL; however, those are not necessarily the underprivileged or marginalized. Identifying populations with high exposure levels is critical to influencing lighting policies to ease related health implications.

Light at night and lung cancer risk: A worldwide interdisciplinary and time-series study.

Background: Light at night (LAN) has become a concern in interdisciplinary research in recent years. This global interdisciplinary study aimed to explore the exposure-lag-response association between LAN exposure and lung cancer incidence. Methods: LAN data were obtained from the Defense Meteorological Satellite Program's Operational Linescan System. Data of lung cancer incidence, socio-demographic index, and smoking prevalence of populations in 201 countries/territories from 1992 to 2018 were collected from the Global Burden of Disease Study. Spearman correlation tests and population-weighted linear regression analysis were used to evaluate the correlation between LAN exposure and lung cancer incidence. A distributed lag nonlinear model (DLNM) was used to assess the exposure-lag effects of LAN exposure on lung cancer incidence. Results: The Spearman correlation coefficients were 0.286-0.355 and the population-weighted linear regression correlation coefficients were 0.361-0.527. After adjustment for socio-demographic index and smoking prevalence, the Spearman correlation coefficients were 0.264-0.357 and the population-weighted linear regression correlation coefficients were 0.346-0.497. In the DLNM, the maximum relative risk was 1.04 (1.02-1.06) at LAN exposure of 8.6 with a 2.6-year lag time. After adjustment for socio-demographic index and smoking prevalence, the maximum relative risk was 1.05 (1.02-1.07) at LAN exposure of 8.6 with a 2.4-year lag time. Conclusion: High LAN exposure was associated with increased lung cancer incidence, and this effect had a specific lag period. Compared with traditional individual-level studies, this group-level study provides a novel paradigm of effective, efficient, and scalable screening for risk factors.

Artificial light at night decreases leaf herbivory in typical urban areas.

Artificial light at night (ALAN) is exerting growing pressure on natural ecosystems, but its impact on biological interactions remains unclear. This study aimed to assess how ALAN influences leaf functional traits and herbivory in two prevalent street tree species (Styphnolobium japonicum (L.) Schott and Fraxinus pennsylvanica) through field surveys and paired experiments in the urban areas of Beijing, China. We found that ALAN led to increased leaf toughness and decreased levels of leaf herbivory. Additionally, ALAN showed species-specific effects on leaf nutrients, size as well as defense substances. The findings illustrate that ALAN can significantly alter some key functional traits and ecological processes (nutrient cycling, energy flow). In general, we suggest that high ALAN intensity will be detrimental to the energy flow from urban plants to higher trophic levels, posing a potential threat to the maintenance of biodiversity (e.g., arthropod diversity, bird diversity) in urban ecosystems.

Short-term exposure to indoor artificial light at night during sleep impairs cardiac autonomic function of young healthy adults in China.

The artificial light at night (ALAN) exposure has emerged as a significant environmental and public health concern globally. However, there is far less evidence on the health effects of indoor ALAN than on outdoor ALAN. Moreover, evidence on cardiovascular effects of indoor ALAN is more limited. To evaluate the association between short-term exposure to ALAN during sleep with heart rate variability (HRV) in young healthy adults, as well as the mediating role of blood oxygen saturation (SpO2), and to further explore the intervention effects of shading habits, this prospective repeated measurement study was conducted among 81 adults with 150 nights (1324h) of HRV monitoring. HRV and SpO2 were monitored during sleep, concurrently with the measurement of indoor and outdoor ALAN. Shading habits were defined as whether to wear blindfolds or draw bed curtains during sleep, and were collected by questionnaires. Linear mixed-effect model was conducted to assess the association between ALAN exposure and HRV indices. The role of SpO2 in the association was analyzed using mediation analyses. We found that indoor ALAN exposure reduced parasympathetic activity and imbalanced cardiac autonomic function. We also found that the use of outdoor ALAN may underestimate or misestimate the potential health effects of ALAN. A significant mediation effects were observed on standard deviation of normal-to-normal intervals (SDNN; p-value for ACME = 0.014) and the ratio of low frequency power to high frequency power (LF/HF; p-value for ACME = 0.026) through minimum SpO2 after indoor ALAN exposure. The association between indoor ALAN and HRV was more pronounced among participants without shading habits during sleep. This study provides general population-based evidence that short-term exposure to indoor ALAN was significantly associated with impaired HRV, and SpO2 partially mediated the association. Improve shading habits during sleep may mitigate the adverse effects of indoor ALAN.

Disrupted Circadian Rhythms and Substance Use Disorders: A Narrative Review.

Substance use disorder is a major global health concern, with a high prevalence among adolescents and young adults. The most common substances of abuse include alcohol, marijuana, cocaine, nicotine, and opiates. Evidence suggests that a mismatch between contemporary lifestyle and environmental demands leads to disrupted circadian rhythms that impair optimal physiological and behavioral function, which can increase the vulnerability to develop substance use disorder and related problems. The circadian system plays an important role in regulating the sleep-wake cycle and reward processing, both of which directly affect substance abuse. Distorted substance use can have a reciprocal effect on the circadian system by influencing circadian clock gene expression. Considering the detrimental health consequences and profound societal impact of substance use disorder, it is crucial to comprehend its complex association with circadian rhythms, which can pave the way for the generation of novel chronotherapeutic treatment approaches. In this narrative review, we have explored the potential contributions of disrupted circadian rhythms and sleep on use and relapse of different substances of abuse. The involvement of circadian clock genes with drug reward pathways is discussed, along with the potential research areas that can be explored to minimize disordered substance use by improving circadian hygiene.

Exposure to light at night (LAN) and risk of overweight/obesity, hypertension, and diabetes: a systematic review and meta-analysis.

Current studies have presented conflicting findings regarding the associations between light at night (LAN) exposure and the risk of overweight/obesity, hypertension, and diabetes. Our study systematically summarized the evidence of the association between LAN exposure and the risk of overweight/obesity, hypertension, and diabetes. We searched five databases (PubMed, Web of Science, Embase, Scopus, and Cochrane) for observational studies published up to 1 August 2023. The pooled odds ratio (ORs) and 95% confidence intervals (CIs) were estimated by random-effects models for the association. Eighteen studies were included in the meta-analysis. Compared with the group with the lowest level of LAN, the group with the highest level of LAN is associated with an increased risk of overweight/obesity (pooled OR = 1.19, 95%CI: 1.13-1.26), hypertension (pooled OR: 1.86, 95% CI:1.28-2.72), and diabetes (pooled OR = 1.21, 95%CI: 1.07-1.31). Our meta-analysis demonstrated LAN exposure is associated with increased risk of overweight/obesity, hypertension, and diabetes.

Noise and light exposure and cardiovascular outcomes: A review of evidence, potential mechanisms and implications.

Cardiovascular diseases (CVD) are the leading cause of global non-communicable disease-related deaths. In recent years there has been increasing discussion about the influence of environmental risk factors, including noise and light, on the occurrence and course of these conditions. Recent studies highlight the impact of road traffic noise on an elevated risk of stroke and increased mortality in the course of coronary artery disease (CAD). In the case of threats arising from light pollution, there are more limited published studies; however, these show an increased hospitalization risk associated with CAD. Existing analyses cannot dismiss these environmental factors, highlighting the need for further research. Future studies should investigate not only road traffic noise but also consider railway and aircraft noise. Additionally, research on light pollution should include younger individuals too. In the future, incorporating individual assessments of noise and light pollution exposure, along with the identification of particularly vulnerable groups, could contribute to refining methods of individual risk stratification and implementing new preventive strategies.

Personal light exposure patterns and incidence of type 2 diabetes: analysis of 13 million hours of light sensor data and 670,000 person-years of prospective observation.

Background: Light at night disrupts circadian rhythms, and circadian disruption is a risk factor for type 2 diabetes. Whether personal light exposure predicts diabetes risk has not been demonstrated in a large prospective cohort. We therefore assessed whether personal light exposure patterns predicted risk of incident type 2 diabetes in UK Biobank participants, using ∼13 million hours of light sensor data. Methods: Participants (N = 84,790, age (M ± SD) = 62.3 ± 7.9 years, 58% female) wore light sensors for one week, recording day and night light exposure. Circadian amplitude and phase were modeled from weekly light data. Incident type 2 diabetes was recorded (1997 cases; 7.9 ± 1.2 years follow-up; excluding diabetes cases prior to light-tracking). Risk of incident type 2 diabetes was assessed as a function of day and night light, circadian phase, and circadian amplitude, adjusting for age, sex, ethnicity, socioeconomic and lifestyle factors, and polygenic risk. Findings: Compared to people with dark nights (0-50th percentiles), diabetes risk was incrementally higher across brighter night light exposure percentiles (50-70th: multivariable-adjusted HR = 1.29 [1.14-1.46]; 70-90th: 1.39 [1.24-1.57]; and 90-100th: 1.53 [1.32-1.77]). Diabetes risk was higher in people with lower modeled circadian amplitude (aHR = 1.07 [1.03-1.10] per SD), and with early or late circadian phase (aHR range: 1.06-1.26). Night light and polygenic risk independently predicted higher diabetes risk. The difference in diabetes risk between people with bright and dark nights was similar to the difference between people with low and moderate genetic risk. Interpretation: Type 2 diabetes risk was higher in people exposed to brighter night light, and in people exposed to light patterns that may disrupt circadian rhythms. Avoidance of light at night could be a simple and cost-effective recommendation that mitigates risk of diabetes, even in those with high genetic risk. Funding: Australian Government Research Training Program.

Artificial light and cloud cover interact to disrupt celestial migrations at night.

The growth of human activity and infrastructure has led to an unprecedented rise in the use of Artificial Light at Night (ALAN) with demonstrable impacts on ecological communities and ecosystem services. However, there remains very little information on how ALAN interacts with or obscures light from celestial bodies, which provide vital orientating cues in a number of species. Furthermore, no studies to date have examined how climatic conditions such as cloud cover, known to influence the intensity of skyglow, interact with lunar irradiance and ALAN over the course of a lunar cycle to alter migratory abilities of species. Our night-time field study aimed to establish how lunar phase and climatic conditions (cloud cover) modulate the impact of ALAN on the abundance and migratory behaviour of Talitrus saltator, a key sandy beach detritivore which uses multiple light associated cues during nightly migrations. Our results showed that the number and size of individuals caught decreased significantly as ALAN intensity increased. Additionally, when exposed to ALAN more T. saltator were caught travelling parallel to the shoreline, indicating that the presence of ALAN is inhibiting their ability to navigate along their natural migration route, potentially impacting the distribution of the population. We found that lunar phase and cloud cover play a significant role in modifying the impact of ALAN, highlighting the importance of incorporating natural light cycles and climatic conditions when investigating ALAN impacts. Critically we demonstrate that light levels as low as 3 lx can have substantial effects on coastal invertebrate distributions. Our results provide the first evidence that ALAN impacted celestial migration can lead to changes to the distribution of a species.