Artificial Light At Night Research Articles

Artificial light at night affects the daily profile of pulse pressure and protein expression in the thoracic aorta of rats

Artificial light at night (ALAN) disrupts 24-h variability of blood pressure, but the molecular mechanisms underlying these effects are unknown. Therefore, we analysed the daily variability of pulse pressure, the maximum value of acceleration rate of aortic pressure (dP/dt(max)) measured by telemetry and protein expression in the thoracic aorta of normotensive male rats exposed to ALAN (1–2 lx) for 3 weeks. Daily, 24-h variability of pulse pressure and dP/dt(max) was observed during a regular light/dark regimen with higher values during the dark compared to the light phase of the day. ALAN suppressed 24-h variability and enhanced ultradian (<12-h) periods of pulse pressure and dP/dt(max) in duration-dependent manners. From beat-to-beat blood pressure variability, ALAN decreased low-frequency bands (a sympathetic marker) and had minimal effects on high-frequency bands. At the molecular level, ALAN decreased angiotensin II receptor type 1 expression and reduced 24-h variability. ALAN caused the appearance of 12-h oscillations in transforming growth factor β1 and fibulin 4. Expression of sarco/endoplasmic reticulum Ca2+-ATPase type 2 was increased in the middle of the light and dark phase of the day, and ALAN did not affect its daily and 12-h variability. In conclusion, ALAN suppressed 24-h variability of pulse pressure and dP/dt(max), decreased the power of low-frequency bands and differentially affected the expression of specific proteins in the rat thoracic aorta. Suppressed 24-h oscillations by ALAN underline the pulsatility of individual endocrine axes with different periods, disrupting the cardiovascular control of central blood pressure.

Outdoor artificial light at night exposure and gestational diabetes mellitus: a case-control study.

This study aims to explore the association between outdoor artificial light at night (ALAN) exposure and gestational diabetes mellitus (GDM). This study is a retrospective case-control study. According with quantiles, ALAN has been classified into three categories (Q1-Q3). GDM was diagnosed through oral glucose tolerance tests. Conditional logistic regression models were used to evaluate the association between ALAN exposure and GDM risk. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Restricted cubic spline analysis (RCS) was utilized to investigate the no liner association between ALAN and GDM. A total of 5,720 participants were included, comprising 1,430 individuals with GDM and 4,290 matched controls. Pregnant women exposed to higher levels of ALAN during the first trimester exhibited an elevated risk of GDM compared to those with lower exposure levels (Q2 OR = 1.39, 95% CI 1.20-1.63, p < 0.001); (Q3 OR = 1.70, 95% CI 1.44-2.00, p < 0.001). Similarly, elevated ALAN exposure during the second trimester also conferred an increased risk of GDM (second trimester: Q2 OR = 1.70, 95% CI 1.45-1.98, p < 0.001; Q3 OR = 2.08, 95% CI 1.77-2.44, p < 0.001). RCS showed a nonlinear association between ALAN exposure and GDM risk in second trimester pregnancy, with a threshold value of 4.235. Outdoor ALAN exposure during pregnancy is associated with an increased risk of GDM.

Artificial light at night bans Chaoborus from vital epilimnetic waters

Artificial light at night (ALAN) is known to affect organisms in terrestrial ecosystems and adjacent litoral habitats. In the present study, we tested the effect of ALAN on the spatial distribution of organisms in open waters, using the insect larvae of Chaoborus flavicans as an example. During the day C. flavicans typically hide from visually hunting fish in deep, dark, anoxic waters. On safer nights, they forage in rich subsurface waters. Nighttime field tests revealed that light from an HPS street lamp mounted on a boat anchored in open water attracted planktivorous fish, but deterred planktonic Chaoborus from rich but risky surface waters. Chaoborus did not descend to the safest, anoxic hypolimnion, but remained in hypoxic mid-depth metalimnion, which does not appear to be a perfect refuge. Neither light gradient nor food distribution fully explained their mid-depth residence under ALAN conditions. A further laboratory test revealed a limited tolerance of C. flavicans to anoxia. Half of the test larvae died after 38 h at 9 °C in anoxic conditions. The trade-off between predation risk and oxygen demand may explain why Chaoborus did not hide in deep anoxic waters, but remained in the riskier metalimnion with residual oxygen under ALAN conditions.

When night becomes day: Artificial light at night alters insect behavior under semi-natural conditions

Light is the most important Zeitgeber for temporal synchronization in nature. Artificial light at night (ALAN) disrupts the natural light-dark rhythmicity and thus negatively affects animal behavior. However, to date, ALAN research has been mostly conducted under laboratory conditions in this context. Here, we used the field cricket, Gryllus bimaculatus, to investigate the effect of ALAN on insect behavior under semi-natural conditions, i.e., under shaded natural lighting conditions, natural temperature and soundscape. Male crickets were placed individually in outdoor enclosures and exposed to ALAN conditions ranging from <0.01 to 1500 lx intensity. The crickets' stridulation behavior was recorded for 14 consecutive days and nights and their daily activity patterns were analysed. ALAN impaired the crickets' stridulation rhythm, evoking a change in the crickets' naturally synchronized daily activity period. This was manifested by a light-intensity-dependent increase in the proportion of insects demonstrating an intrinsic circadian rhythm (free-run behavior). This also resulted in a change in the population's median activity cycle period. These ALAN-induced effects occurred despite the crickets' exposure to almost natural conditions. Our findings provide further validity to our previous studies on ALAN conducted under lab conditions and establish the deleterious impacts of ALAN on animal behavioral patterns. TeaserArtificial light at night alters cricket behavior and desynchronizes their stridulation even under near-natural conditions.

Carry-over effect of artificial light at night on daytime mating activity in an ecologically important detritivore, the amphipod Gammarus pulex.

Artificial light at night (ALAN) is a growing environmental problem influencing the fitness of individuals through effects on their physiology and behaviour. Research on animals has primarily focused on effects on behaviour during the night, whereas less is known about effects transferred to daytime. Here, we investigated in the lab the impact of ALAN on the mating behaviour of an ecologically important freshwater amphipod, Gammarus pulex, during both daytime and nighttime. We manipulated the presence of ALAN and the intensity of male-male competition for access to females, and found the impact of ALAN on mating activity to be stronger during daytime than during nighttime, independent of male-male competition. At night, ALAN only reduced the probability of precopula pair formation, while during the daytime, it both decreased general activity and increased the probability of pair separation after pair formation. Thus, ALAN reduced mating success in G. pulex not only directly, through effects on mating behaviour at night, but also indirectly through a carry-over effect on daytime activity and the ability to remain in precopula. These results emphasise the importance of considering delayed effects of ALAN on organisms, including daytime activities that can be more important fitness determinants than nighttime activities.

Artificial night light and thyroid cancer.

The occurrence of thyroid cancer (TC) has increased in recent decades. Exposure to outdoor artificial light at night (ALN) is associated with an increased risk of cancer. To investigated the impact of ALN, as a significant environmental pollutant, on TC incidence worldwide. The assessment involved analyzing satellite ALN data in conjunction with TC incidence data [adjusted standardized rate (ASR)], while considering the quality of cancer registries (QCR), gross domestic product (GDP) per person, and health expenditure per person (HEP) for each country. Results indicated a correlation between higher ASR and ALN exposure percentages, particularly in countries with higher GDP or HEP quartiles (all P< 0.05). Significant differences in ASR were observed across QCR levels, both high and low quality (all P < 0.05), but not in countries without registry activity. However, when evaluating ASR against ALN exposure percentages while considering GDP/HEP quartiles or QCR levels, no significant associations were found (all P > 0.10). The findings suggest a potential link between higher GDP and adverse health conditions, serving as possible risk factors for TC, rather than a direct association with ALN. Limitations include the use of cross-sectional data, temporal misalignment, and reliance on ALN as a socioeconomic proxy. It is proposed that light pollution might be connected to a lifestyle conducive to carcinogenesis. Additionally, the presence of higher GDP/HEP could enhance access to diagnostic resources, potentially facilitating TC diagnosis and inclusion in cancer registries.

Abstract MP77: Both Racial/Ethnic Residential Segregation and Exposure to Outdoor Artificial Light at Night May Impact Cardiovascular Health but Perhaps Not Through Self-Reported Sleep

Introduction: Due to structural racism, minoritized racial/ethnic groups are overrepresented in racially segregated areas of concentrated disadvantage in which residences may be less protective against outdoor artificial light at night (ALAN). Both racial/ethnic residential segregation (RRS) and ALAN are associated with disparities in both sleep duration, potentially through ALAN exposures in segregated areas disrupting melatonin production, and cardiovascular health (CVH). However, few studies have investigated pathways between RRS and ALAN, sleep, and CVH. We sought to investigate sleep duration as a potential mediator between RRS and ALAN exposures and CVH among US adults. Hypothesis: We hypothesized that (1) ALAN would disproportionately burden minoritized racial/ethnic groups, (2) sleep duration would mediate associations between both RRS and ALAN and CVH, and (3) associations would vary by race/ethnicity. Methods: We used data collected from 2011 National Health Interview Survey adult participants reporting sleep duration (short [&lt;7 hours(h)]), recommended [7-9 h], long [&gt;9 h]) and CVH (defined as yes vs. no to all: never/former smoking, BMI 18-&lt;25 kg/m 2 , meets physical activity guidelines, and no prior diagnosis of dyslipidemia, hypertension, or pre-diabetes/diabetes). Participants’ home addresses were geographically linked to the 2012 American Community Survey 5-year estimates to assess RRS, measured by the local Getis-Ord G i * statistic (z-scores) categories: low (z&lt;0), medium (0≤z≤1.96), and high (z&gt;1.96). Quintiles of residential ALAN were estimated from 2010-2011 US Defense Meteorological Satellite Program’s Operational Linescan System values. We used robust Poisson regression adjusted for sociodemographic characteristics, estimated mediation through sleep duration with the Sobel’s test, and assessed effect modification by race/ethnicity. Results and Conclusions: Among 18,057 participants (mean age±SE =45±0.2 years); 35%, 44%, and 21% resided in low, medium, and highly segregated neighborhoods, respectively. ALAN was highest among non-Hispanic White adults. Prevalence of short and long sleep duration overall were 31% and 3% and highest among Black adults (39% and 4%). High (vs. low) RRS was associated with a higher prevalence of CVH (PR=1.13 [95% CI:1.01-1.26]). However, higher ALAN (Q5 vs. Q1) was associated with a lower prevalence of CVH (PR=0.79 [95% CI:0.66-0.95]). Sleep did not appear to mediate associations, which did not vary by race/ethnicity. In conclusion, self-reported sleep did not mediate associations between RRS or ALAN and CVH. Nonetheless, further study using objective measures is warranted given the biological plausibility. The findings/conclusions in this research are those of the authors and do not necessarily represent the views of the Research Data Center, National Center for Health Statistics, or CDC.

Associations between bird song attributes and noise, light, date, and temperature: Vermilion flycatchers (Pyrocephalus rubinus) sing shorter and higher pitched songs in territories with more artificial light at night

Urban noise and artificial light at night (ALAN) are global pollutants affecting animal acoustic communication. A previous study that measured noise, but not ALAN, found that vermilion flycatchers produce longer songs in noisier territories. A subsequent study in another population, that measured noise and ALAN, found that males emit longer songs in brighter, but not noisier, territories. The negative result could be due a lack of sufficient noise variation in the latter study. We evaluated the contribution of noise and ALAN on song length, provided sufficient variation in noise and ALAN. We also measured song peak frequency. During the dawn chorus, we recorded songs of 41 vermilion flycatchers in two populations (UNAM and PERM), and measured noise, ALAN, and temperature. For the population with sufficient noise and ALAN variation (UNAM), we confirmed that song length was positively associated with noise; it was also negatively associated with ALAN, especially in those males recorded late in the breeding season. At UNAM, we found an overall positive association between song pitch and ALAN; additionally, males singing at relatively low ambient temperatures (12-15 °C) produced higher pitched songs as ALAN increased. Those singing closer to new moon and at relatively low ambient noise levels (43-54 dB[A]) sang higher pitched songs in brighter territories; these two results should be taken cautiously. Our results show that light, noise, date, and temperature are associated in unexpected ways with song length and pitch, potentially affecting song information content and sexual selection.

In the Spotlight: Bat Activity Shifts in Response to Intense Lighting of a Large Railway Construction Site

Artificial light at night (ALAN) is a major form of anthropogenic pollution, disrupting nocturnal wildlife behaviour and ecosystem function. Large construction sites are typically located at the intersection of urban and natural areas, introducing intense lighting into previously dark natural habitats. This study examines the responses of bats to intense nighttime lighting at a major construction site associated with a linear transport infrastructure (LTI) project. We used passive acoustic monitoring to record bat activity and species richness at the construction site and in adjacent urban and natural areas with different lighting levels. Generalist species, such as Pipistrellus kuhlii and Nyctalus leisleri, were attracted to illuminated areas, likely due to increased prey availability. Conversely, sensitive species, such as those from the Myotis and Plecotus genera, along with Barbastella barbastellus, avoided illuminated areas, particularly the construction site. Species richness was significantly lower at the construction site compared to other environments, reflecting ALAN’s barrier effect on movements and habitat accessibility for more sensitive species. The findings highlight the ecological impacts of introducing ALAN to previously unlit natural environments, underscoring the urgent need for implementing ALAN mitigation strategies in urban planning and construction practices to protect biodiversity in urbanising areas.

Assessment of reproductive hormones in prepubertal and postpubertal rats (&lt;i&gt;Rattus norvegicus&lt;/i&gt;) on chronic exposure to various spectra of artificial light at night

Exposures to Artificial Light at Night (ALAN) is on the increase with resultant varied physiological impact related to the light spectrum via the non-visual pathway. This study examined the effects of various spectra of ALAN on Testosterone (Te), Progesterone (Pr) and Estradiol (Es) in rats exposed to Blue (BL), Green (GL), Yellow (YL), Red (RL), White (WL) and Darkness (DD) light wave-lengths while Ambient light (CL) served as the control. Dams with their post-natal day 1 pups were housed in cages exposed to various light wavelengths for 12 hours: (6:00pm–6:00am) daily for 126 days. At d63 and d126, five rats per treatments were euthanized; blood serum was collected and the serum hormones: Te, Es and Pr were analysed using ELISA. The results showed that light treatments had significant effect on the level of Te at d63 but not at d126 in male rats. At d63, onset of puberty, Te was significantly highest (p &lt; 0.05) under BL. In females exposed to YL and WL at d126, Te was significant high and Es was significantly low. Estradiol was heightened significantly (p &lt; 0.05) in both sexes exposed to RL. In conclusion, BL seemed to stimulate early sexual development in males, WL and GL enhanced post-pubertal male albino rat reproductive system while RL provided the best reproductive environment for females in the long term. Long periods of exposure to YL seemed to pose risks for male and female reproductive function.

The effect of artificial light at night (ALAN) on the characteristics of diapause of Aedes albopictus

BackgroundRecently, the effect of artificial light at night (ALAN) on the physiology and behavior of insects has gradually attracted the attention of researchers and has become a new research topic. Aedes albopictus is an important vector that poses a great public health risk. Further studies on the diapause of Ae. albopictus can provide a basis for new vector control, and it is also worth exploring whether the effect of ALAN on the diapause of Ae. albopictus will provide a reference for the prevention and control of infectious diseases mediated by Ae. albopictus. MethodsIn this study, we experimentally studied the diapause characteristics of different geographical strains of Ae. albopictus under the interference of ALAN, explored the effect of ALAN on the diapause of Ae. albopictus and explored the molecular mechanism of ALAN on the diapause process through RNA-seq. ResultsAs seen from the diapause incidence, Ae. albopictus of the same geographic strain showed a lower diapause incidence when exposed to ALAN. The differentially expressed genes (DEGs) were mainly enriched in signaling and metabolism-related pathways in the parental females and diapause eggs of the ALAN group. ConclusionsALAN inhibits Ae. albopictus diapause. In the short photoperiod induced diapause of Ae. albopictus in temperate strain Beijing and subtropical strain Guangzhou, the disturbance of ALAN reduced the egg diapause rate and increased the egg hatching rate of Ae. albopictus, and the disturbance of ALAN also shortened the life cycle of Ae. albopictus eggs after hatching.

Artificial Light at Night Reduces Flashing in Photinus and Photuris Fireflies During Courtship and Predation

Artificial light at night (ALAN) affects species-specific communication in a wide range of nocturnal species, including fireflies (Lampyridae). Fireflies rely on bioluminescent signals for communicating. In this study, we conducted two manipulative field experiments to evaluate the effect of artificial light at night on the flashing activity of male and female neotropical fireflies during courtship and predation. Our results showed a significant reduction in the flashing activity of both males and females exposed to ALAN during courtship and predation. Remarkably, the effect of ALAN on male flashing activity seems to be independent of female flashing activity. In conclusion, ALAN disrupts bioluminescent intraspecific (courtship) and interspecific (predation) communication, which in turn could influence mating success, thus negatively affecting neotropical firefly populations in the long term. Our findings contribute to understanding the challenges faced by neotropical firefly communities in the presence of ALAN.

How Mobility and Temporal Contexts May Affect Environmental Exposure Measurements: Using Outdoor Artificial Light at Night (ALAN) and Urban Green Space as Examples

Temporal contexts are essential for the derivation of causally relevant environmental exposure in environmental and public health studies. We argue that the proper temporal contexts need further emphasis in the mobility-oriented research paradigm and articulate this issue using a study in Hong Kong. We use people’s exposure to outdoor artificial light at night (ALAN) and green space as two essential examples. We recruited 208 participants from two representative communities in Hong Kong and derived their mobility-oriented environmental exposures from high-resolution remote sensing data and Google Street View imagery. We employed one-standard-deviational ellipses to quantitatively represent participants’ activity spaces, and we further used participants’ seven-day Global Positioning System trajectories to derive their spatiotemporally weighted exposures to green space and outdoor ALAN in different temporal contexts. Multiple t tests were used to examine the disparities in activity spaces and measured exposures in different temporal contexts, and these exposure measurements were then used to predict people’s health outcomes. We found that people’s activity spaces are significantly different in size between day and night, for both weekdays and weekends, and in both geographic contexts. We further observed that improper temporal contexts could lead to significantly different environmental exposure levels and causally irrelevant modeling results.

Embedding sustainability into the design of street lighting

Light pollution is an increasing problem and Artificial Light at Night (ALAN) affects nature in many ways. The Norwegian Road Authorities (SVV) initiated a collaboration with the Norwegian Institute for Bioeconomy (NIBIO) and the University of South-Eastern Norway (USN) to find measures that can help reduce the negative impacts of road lighting on the environment and nature. While USN has looked more generally at sustainable lighting design and ways to reduce the negative effects of road lighting, NIBIO has focused on how road lighting affects insects. We study how the light from roads contributes to light pollution, with the final aim to know more about what measures most effectively reduce the negative effects of road lighting. In this pilot study of light levels in two transects beside a road, the results show that the light levels decreased relatively fast as the distance to the light source increased. Thus, the direct light from the road lighting might not be the most prominent addition to the light pollution in the open landscape. On the other hand, the measurements showed some light influence from the road up to around 160 meters from the road, although the levels were low. While the light was below the detection limit, the light source was visible as a point source at a very large distance. This observation addresses the question of whether organisms are influenced by the average light energy per area, or the intensity of a source as observed from a distance (irradiance vs. radiance). Additional sources of light pollution may affect the result, such as unshielded private light sources and sky glow. This project aims to find measures that can help reduce the negative impacts of road lighting on the environment and nature. We study how the light from roads contributes to different components of light pollution, like skyglow, light trespass and luminance from the light source.

Artificial light at night (ALAN) pollution alters bat lunar chronobiology: insights from broad-scale long-term acoustic monitoring

BackgroundThe timing of behavior and habitat use of nocturnal animals can be influenced by the lunar cycle in nature. The prevalence of artificial light at night (ALAN) has been recognized as a source of environmental pollution. The interaction between ALAN and the lunar cycle on bat behavior is important for understanding anthropogenic effects on bats. We utilized a decade (2012–2022) of acoustic monitoring data collected in North Carolina, United States, to investigate the relationship between bat activity, lunar cycle, and light pollution. We examined whether the amount of lunar illumination affected species-specific nightly activity and whether hourly bat activity patterns varied between nights with different moon phases. We further investigated if the relationship between bat activity and the lunar cycle might be altered by light pollution.ResultsWe found that seven bat species showed activity variation across nights in relation to the amount of moon illumination when ALAN was absent. In general, bats were less active on full moon nights compared to new moon nights. Light pollution interacted with the bat–lunar relationship in five of the seven species, masking the effect of the lunar cycle. We identified delayed bat activity patterns on nights with a full or waxing moon in seven species, and light pollution altered that pattern in four species. Overall, ALAN was associated with decreased bat activity independent of lunar cycle effects.ConclusionsOur study demonstrated that at a broad spatial scale, ALAN negatively affected many North American temperate bat species and altered their lunar chronobiology. As light pollution is spreading to historically dark areas and habitats, ALAN might couple with other threats, such as the white-nose syndrome or climate change, to cause cascading damage in the environment that depends on ecosystem services such as pest control provided by bats. We argue that further research and conservation actions are needed to mitigate the impact of light pollution.

Artificial light at night causes community instability of bacterial community in urban soils

Urban soils host diverse bacteria crucial for ecosystem functions and urban health. As urbanization rises, artificial light at night (ALAN) imposes disturbances on soil ecosystems, yet how ALAN affects the structure and stability of soil bacterial community remains unclear. Here we coupled a short-term incubation experiment, community profiling, network analysis, and in situ field survey to assess the ecological impacts of ALAN. We showed that ALAN influenced bacterial compositions and shifted the bacterial network to a less stable phase, altering denitrification potential. Such transition in community stability probably resulted from an ALAN-induced decrease in competition and/or an increase in facilitation, in line with the Stress Gradient Hypothesis. Similar destabilizing effects were also detected in bacterial networks in multiple urban soils subjected to different levels of ALAN stress, supporting the action of ALAN on naturally-occurring soil bacterial communities. Overall, our findings highlight ALAN as a new form of anthropogenic stress that jeopardizes the stability of soil bacterial community, which would facilitate ecological projection of expanding ALAN exposure.

The effect of artificial light at night on a nocturnalprimate.

Anthropogenic disturbance is a major threat to biodiversity. An anthropogenic disturbance that is rarely addressed for nonhuman primates is the effect of artificial light at night (ALAN) which is defined by the spread of artificial lighting at night which eliminates natural darkness. Artificial light at night can result from streetlights, or indirectly from sky glow (artificial light that is scattered and reflected back to earth by the atmosphere). Research has demonstrated that artificial lighting causes changes in animal behavior, reproductive success, survivorship, as well as can alter the composition of the communities. The goal of this paper is to explore how the behavior of spectral tarsiers, Tarsius spectrumgurskyae, is modified in response to artificial light. We conducted this study at Tangkoko Nature Reserve on the easternmost tip of the northern arm of Sulawesi, Indonesia. The results of this study suggest that in response to artificial light tarsiers increase their time spent travelling and foraging, left their sleeping sites earlier and returned to them later thereby extending their daily activity time. The tarsiers also left their sleeping trees at lower heights, gave fewer vocalizations and fewer alarm calls each night in response to the additional artificial light. The tarsier's lengthened night might be leading to a change in interspecific competition for food as well as increase the ability of potential predators to locate the tarsiers. Additional research on the effect of ALAN on primates is clearly needed.

Corals nitrogen and carbon isotopic signatures alters under Artificial Light at Night (ALAN)

This study examines the impact of Artificial Light at Night (ALAN) on two coral species, Acropora eurystoma and Pocillopora damicornis, in the Gulf of Aqaba/Eilat Red Sea, assessing their natural isotopic responses to highlight changes in energy and nutrient sourcing due to sensory light pollution. Our findings indicate significant disturbances in photosynthetic processes in Acropora eurystoma, as evidenced by shifts in δ13C values under ALAN, pointing to alterations in carbon distribution or utilization. In Pocillopora damicornis, similar trends were observed, with changes in δ13C and δ15N values suggesting a disruption in its nitrogen cycle and feeding strategies.The study also uncovers species-specific variations in heterotrophic feeding, a crucial factor in coral resilience under environmental stress, contributing to the corals' fixed carbon budget. Light measurements across the Gulf demonstrated a gradient of light pollution which possess the potential of affecting marine biology in the region. ALAN was found to disrupt natural diurnal tentacle behaviors in both coral species, crucial for prey capture and nutrient acquisition, thereby impacting their isotopic composition and health.Echoing previous research, our study underscores the need to consider each species' ecological and physiological contexts when assessing the impacts of anthropogenic changes. The findings offer important insights into the complexities of marine ecosystems under environmental stress and highlight the urgency of developing effective mitigation strategies.

Short-time exposure to light at night affects incubation patterns and correlates with subsequent body weight in great tits (Parus major).

Artificial light at night (ALAN) widely affects wildlife by blurring light-dark differences, including transitions such as sunrise and sunset, thereby affecting regulation of diel rhythms. As a result, activity onsets in many wild diurnal songbirds advance under ALAN. From chronobiological studies, it is known that the direction and strength of the response to light depends on when during the night exposure takes place. However, these experiments are mostly done under continuous light conditions, when animals have free-running rhythms. It remains unclear whether phase-dependence also holds in entrained, wild songbirds; i.e., does the effect of ALAN on activity patterns differ between exposure in the morning compared to the evening? This information is essential to assess the effects of mitigation measures by limiting ALAN to selected times of the night. We exposed incubating great tits (Parus major) inside the nest-box to 4 h of dim light, of which 1 h overlapped with dawn before sunrise or dusk after sunset. We found a small advancing effect of morning-light on activity onset and of evening-light on offset compared to dark controls but not vice versa. Breeding success and chick condition were unaffected by the light treatments. However, light-treated females had lower weights 9-18 days after the end of the treatment compared to the controls, independent of whether ALAN occurred in the morning or the evening, indicating possible costs of ALAN. Despite the weak behavioral response, ALAN might have affected the females' circadian clock or physiology resulting in lower body condition.

The effects of artificial light at night (ALAN) on the circadian biology of marine animals

The effects of artificial light at night (ALAN) on the circadian biology of marine animals