Adverse health effects of nighttime lighting: comments on American Medical Association policy statement

Spatiotemporal Dynamics of COVID-19 Pandemic City Lockdown: Insights From Nighttime Light Remote Sensing

The global COVID-19 outbreak severely hampered the growth of the global economy, prompting the implementation of the strictest prevention policies in China. Establishing a significant relationship between changes in nighttime light and COVID-19 lockdowns from a geospatial perspective is essential. In light of nighttime light remote sensing, we evaluated the spatiotemporal dynamic effects of COVID-19 city lockdowns on human activity intensity in the Zhengzhou region. Prior to the COVID-19 outbreak, nighttime light in the Zhengzhou region maintained a significant growth trend, even under regular control measures. However, following the October 2022 COVID-19 lockdown, nighttime light experienced a substantial decrease. In the central area of Zhengzhou, nighttime light decreased by at least 18% compared to pre-lockdown levels, while in the sub-center, the decrease was around 14%. The areas where nighttime light decreased the most in the central region were primarily within a 15 km radius, while in the sub-center, the decrease was concentrated within a 5 km radius. These changes in both statistical data and nighttime light underscored the significant impact of the COVID-19 lockdown on economic activities in the Zhengzhou region.

Immersion in nature enhances neural indices of executive attention

There is conjecture that our modern urban environments place high demand on our attentional resources, which can become depleted over time and cause mental fatigue. Natural environments, on the other hand, are thought to provide relief from this demand and allow our resources to be replenished. While these claims have been assessed with self-report and behavioral measures, there is limited understanding of the neural mechanisms underlying these attentional benefits. The present randomized controlled trial fills this gap in the literature by using electroencephalography to explore three aspects of attention-alerting, orienting, and executive control-from a behavioral and neural perspective. Participants (N = 92) completed the Attention Network Task before and after either a 40-min walk in nature or a 40-min walk in a control, urban environment. Participants that walked in nature reported their walk to be more restorative than those that walked in the urban environment. Furthermore, the nature group showed an enhanced error-related negativity after their walk, an event-related brain component that indexes executive control capacity, whereas the urban group did not. These findings demonstrate that a 40-min nature walk enhances executive control at a neural level, providing a potential neural mechanism for attention restoration in nature.

Urban-rural disparities in the prevalence and trends of depressive symptoms among Chinese elderly and their associated factors

BACKGROUND

This study aimed to examine urban-rural disparities in the prevalence and trends of depressive symptoms (DS) among Chinese elderly and associated factors.

METHODS

A total of 8025, 7808, and 4887 respondents aged 60 years and above were selected from the China Family Panel Studies (CFPS) in 2016, 2018, and 2020, respectively. DS was assessed using a short version of Center for Epidemiologic Studies Depression Scale (CES-D). Twenty-two associated factors from six categories were included in random forest (RF) models. All urban-rural comparisons were conducted based on good model performance.

RESULTS

The DS prevalence among all rural elderly was significantly higher than corresponding urban elderly. This disparity continued to widen among younger elderly, while it continued to narrow among older elderly. The top 10 common leading factors were sleep quality, self-rated health, life satisfaction, memory ability, child relationship, IADL disability, marital status, educational level, and gender. Urban-rural disparities in sleep quality, interpersonal trust, and child relationship continued to widen, while disparities in multimorbidity, hospitalization status, and frequency of family dinner continued to narrow.

LIMITATION

This study may exist recall bias and lacks causal explanation.

CONCLUSIONS

Significant and continuing disparities in the DS prevalence were observed between urban and rural elderly in China, showing opposite trends in younger and older elderly. The top 10 leading associated factors for DS were nearly consistent across urban and rural elderly, with sleep quality having strongest contribution. Urban-rural disparities in associated factors also showed different trends. This study provides a reference for mental health promotion among Chinese elderly.

Association of exposure to artificial light at night during adolescence with blood pressure in early adulthood

Artificial light at night (ALAN) is related to various diseases, such as cancer, obesity, and coronary heart disease. However, its impact on blood pressure in adolescents is not well understood. To investigate this, we conducted a cross-sectional study with a nationwide sample of college students in China, who were freshmen from four disperse universities during Sep. and Oct. 2018. Mean levels of ALAN at participants' residential addresses during 2013-2018 were estimated using time-varying satellite data. The association of the 6-y average of ALAN with blood pressure was estimated by using generalized linear mixed models. A total of 17 046 participants (18.2 ± 0.7 y of age, 46.79% female) from 2,412 counties and cities were included in the final analysis. After a full adjustment for potential confounders, ALAN was positively associated with systolic blood pressure (β = 0.20, p = 0.032) and pulse pressure (β = 0.28, p  = 0.001), but there was no association between ALAN and diastolic blood pressure (β = -0.08, p = 0.213). In the sensitivity analysis, the results consistent with the main analysis were observed. The blood pressure of males and those with a BMI ≤24 kg/m2 were more susceptible to ALAN exposure. Our findings highlight the importance of ALAN management for blood pressure control, particularly among male and normal-weight individuals.

Sleep, light exposure at night, and psychological wellbeing during pregnancy

BACKGROUND

Psychological wellbeing during pregnancy is imperative for optimal maternal outcomes. The present study aimed to determine the association between sleep quality, light exposure at night, and psychological wellbeing in the 2nd and 3rd trimesters of pregnancy.

METHODS

This prospective study was conducted in 9 randomly selected government maternity clinics in Kuala Lumpur, Malaysia. Healthy women aged 20-48 years old with single pregnancy were recruited using convenience sampling (n = 169). Sleep quality, light exposure at night, and psychological wellbeing were self-reported using the Pittsburgh Sleep Quality Index (PSQI), Harvard Light Exposure Assessment (H-LEA), and Depression, Anxiety, and Stress Scale (DASS-21) in the 2nd trimester and followed-up at the 3rd trimester.

RESULTS

During the 2nd and 3rd trimesters of pregnancy, mild to severe symptoms of stress (10.7 and 11.3%), anxiety (42 and 44.3%), and depression (9.6 and 16.6%) were observed among the participants. Adjusted multiple linear regression revealed that poor sleep quality and higher light exposure at night were attributed to greater stress and depression symptoms in the 3rd trimester. Higher lux level exposed from 10 pm to < 1 am was associated with increased stress (β = 0.212, p = 0.037) and depression (β = 0.228, p = 0.024). Only poor sleep quality was observed to adversely affect anxiety (β = 0.243, p = 0.002) and depression levels (β = 0.259, p = 0.001) in the 2nd trimester.

CONCLUSIONS

Present study provided preliminary findings on the association between sleep quality, light at night, and psychological wellbeing of pregnant women. As a recommendation, future research could investigate whether public health interventions aimed at decreasing artificial light at night can benefit sleep quality and the psychological health of pregnant women.

Nonionizing Electromagnetic Irradiations; Biological Interactions, Human Safety

Human is usually exposed to environmental radiation from natural and man-made sources. Therefore, it is important to investigate the effects of exposure to environmental radiation, partly related to understanding and protecting against the risk of exposure to environmental radiation with beneficial and adverse impacts on human life. The rapid development of technologies causes a dramatic enhancement of radiation in the human environment. In this study, we address the biological effects caused by different fractions of non-ionizing electromagnetic irradiation to humans and describe possible approaches for minimizing adverse health effects initiated by radiation. The main focus was on biological mechanisms initiated by irradiation and represented protection, and safety approaches to prevent health disorders.

Adeniyi M, K. Okojie A, Okeke C. Photic Stress and Rhythmic Physiological Processes: Roles of Selenium as a Chronobiotic

Physiological processes exhibit distinct rhythmic patterns influenced by external cues. External cues such as photic signal play an important role in the synchronization of physiological rhythms. However, excess of or indiscriminate exposure to photic signals exerts profound effects on physiological processes, disrupting normal hormonal secretory rhythms, altering sleep/wakefulness cycle, and impairing reproductive function. Alteration in sleep/wakefulness cycle, impairment in reproductive cycle, and disruption of normal hormonal secretory rhythms characterize risk groups for photic stress such as night workers, trans-meridian travelers, and night-active people. Evidence from primary studies is increasing on the tendency of selenium to reset internal biorhythms by targeting circadian proteins and melatonin. The review highlights the chronobiological roles of selenium.

Blue Light-Ocular and Systemic Damaging Effects: A Narrative Review

Light is a fundamental aspect of our lives, being involved in the regulation of numerous processes in our body. While blue light has always existed in nature, with the ever-growing number of electronic devices that make use of short wavelength (blue) light, the human retina has seen increased exposure to it. Because it is at the high-energy end of the visible spectrum, many authors have investigated the theoretical harmful effects that it poses to the human retina and, more recently, the human body, given the discovery and characterization of the intrinsically photosensitive retinal ganglion cells. Many approaches have been explored, with the focus shifting throughout the years from examining classic ophthalmological parameters, such as visual acuity, and contrast sensitivity to more complex ones seen on electrophysiological assays and optical coherence tomographies. The current study aims to gather the most recent relevant data, reveal encountered pitfalls, and suggest future directions for studies regarding local and/or systemic effects of blue light retinal exposures.

Evaluating the Relationship between Circadian Rhythms and Sleep, Metabolic and Cardiovascular Disorders: Current Clinical Evidence in Human Studies

Circadian rhythms are generated by the circadian clock, a self-sustained internal timing system that exhibits 24-h rhythms in the body. Many metabolic, cellular, behavioral and physiological processes are regulated by the circadian clock in coordination with environmental cues. The present study is a comprehensive review of the currently existing evidence concerning the relationship between circadian rhythms and sleep, metabolic, and cardiovascular disorders. We thoroughly searched the online databases PubMed, Scopus, and Web of Science to find the existing clinical studies from the last twenty-three years (2000-2023). Circadian misalignment was found to be associated with an increase in the risk of metabolic disorders, cardiovascular diseases, and obesity, as well as inadequate sleep quality. In this review article, all the included studies had a strength protocol design and all of them were conducted on humans. However, the most common limitations of them were the small sample size and the short time of the intervention. In conclusion, managing the factors that disrupt the optimal function of central and peripheral clocks can help to reduce the risk of metabolic and cardiovascular diseases, improving also sleep quality. Future studies should further explore the underlying mechanisms of the interconnections between circadian clocks and sleep, metabolic, and cardiovascular disorders. This may provide new opportunities for advance chronotherapy approach.

Brain-derived neurotrophic factor Val66Met polymorphism modulates the effects of circadian desynchronization on activity and sleep in male mice

Introduction

Understanding how environmental interact challenges with genetic predispositions modulate health and wellbeing is an important area of biomedical research. Circadian rhythms play an important role in coordinating the multitude of cellular and tissue processes that organisms use to predict and adapt to regular changes in the environment, and robust circadian rhythms contribute to optimal physiological and behavioral responses to challenge. However, artificial lighting and modern round-the-clock lifestyles can disrupt the circadian system, leading to desynchronization of clocks throughout the brain and body. When coupled with genetic predispositions, circadian desynchronization may compound negative outcomes. Polymorphisms in the brain-derived neurotrophic (BDNF) gene contribute to variations in neurobehavioral responses in humans, including impacts on sleep, with the common Val66Met polymorphism linked to several negative outcomes.

Methods

We explored how the Val66Met polymorphism modulates the response to environmental circadian desynchronization (ECD) in a mouse model. ECD was induced by housing adult male mice in a 20 h light-dark cycle (LD10:10; 10 h light, 10 h dark). Sleep and circadian activity were recorded in homozygous (Met) mice and their wild-type (Val) littermates in a standard 24 h LD cycle (LD12:12), then again after 20, 40, and 60 days of ECD.

Results

We found ECD significantly affected the sleep/wake timing in Val mice, however, Met mice maintained appropriate sleep timing after 20 days ECD, but not after 40 and 60 days of ECD. In addition, the rise in delta power at lights on was absent in Val mice but was maintained in Met mice. To elucidate the circadian and homeostatic contribution to disrupted sleep, mice were sleep deprived by gentle handling in LD12:12 and after 20 days in ECD. Following 6 h of sleep deprivation delta power was increased for both Val and Met mice in LD12:12 and ECD conditions. However, the time constant was significantly longer in the Val mice during ECD compared to LD12:12, suggesting a functioning but altered sleep homeostat.

Discussion

These data suggest the Val66Met mutation is associated with an ability to resist the effects of LD10:10, which may result in carriers suffering fewer negative impacts of ECD.

Effects of Morning or Evening Narrow-band Blue Light on the Compensation to Lens-induced Hyperopic Defocus in Chicks

SIGNIFICANCE

Exposure to blue light before bedtime is purported to be deleterious to various aspects of human health. In chicks, blue evening light stimulated ocular growth, suggesting a role in myopia development. To further investigate this hypothesis, we asked if brief blue light altered the compensatory responses to hyperopic defocus.

PURPOSE

Previous work showed that several hours' evening exposure to blue light stimulated ocular growth in chicks, but morning exposure was only effective at a lower illuminance. By contrast, rearing in blue light has inhibited ocular growth in untreated eyes and eyes exposed to form deprivation or defocus. We studied the effects of brief exposures to blue light on the compensation to hyperopic defocus.

METHODS

Chicks wore monocular negative lenses (-10 D) starting at age 10 days. They were subsequently exposed to blue light (460 nm) for 4 hours in the morning or evening for 8 to 9 days ("dim," 200 lux[morning, n = 9; evening, n = 11]; "bright," 600 lux[morning, n = 8; evening, n = 20]); controls wore lenses in white light (n = 14). Ultrasonography was done on days 1, 5, 8, and 9 for "evening" groups and days 1, 6, and 8 for "morning." All data are reported as interocular differences (experimental minus fellow eyes). Refractions were measured on the last day.

RESULTS

For evening exposure, dim blue light enhanced the axial compensation at all times (change in axial length: day 6: 465 vs. 329 μm/9 days, analysis of variance P < .001, P = .03; day 9: 603 vs. 416 μm/9 days, analysis of variance P < .001; P < .05). Bright blue light had a transient inhibitory effect (day 5: 160 vs. 329 μm; P < .005). Refractive errors were consistent with axial growth, with dim causing more myopia than bright (-9.4 vs. -4.7 D; P < .05). Morning blue light had no significant effect.

CONCLUSIONS

We speculate that these findings reflect a complex interaction between illuminance, defocus, and time of day.

An exploration of how the disruption of mainstream schooling during the COVID-19 crisis provided opportunities that we can learn from so that we may improve our future relationship with the more-than-human world

The COVID-19 crisis forced educators globally to reassess delivery of their curricula and educational priorities. Already the worsening climate crisis amid human beings' deleterious relationship with the more-than-human world has caused many educators to demand radical reconsiderations as to the purpose and meaning of education. We ask: how did the disruption of mainstream schooling, during the COVID-19 crisis, provide opportunities that we can learn from so that we may improve our future relationship with the more-than-human world? We examine research that shows children can benefit from outdoor, contemplative pedagogical approaches that differ from their usual indoor classroom experience. Outdoor, contemplative pedagogical approaches involving freedom from "clock-time", as were experienced by some children during the lockdowns, can allow for ways of knowing and states of being that are often marginalised or excluded from mainstream schools in industrial growth societies. We draw on underpinning theory that argues the status quo in schools conforms to a factory model of schooling that prioritises limited ways of knowing and states of being, thus, lacking the perspectives needed to enable children to cultivate a sustained, healthy relationship with nature. We suggest that outdoor contemplative approaches are required that allow children to dwell pedagogically and experience their relationship with the more-than-human world.

Circadian Disruption and Consequences on Innate Immunity and Inflammatory Response

Circadian rhythms control almost all aspects of physiology and behavior, allowing temporal synchrony of these processes between each other, as well as with the external environment. In the immune system, daily rhythms of leukocyte functions can determine the strength of the immune response, thereby regulating the efficiency of defense mechanisms to cope with infections or tissue injury. The natural light/dark cycle is the prominent synchronizing agent perceived by the circadian clock, but this role of light is highly compromised by irregular working schedules and unintentional exposure to artificial light at night (ALAN). The primary concern is disrupted circadian control of important physiological processes, underlying potential links to adverse health effects. Here, we first discuss the immune consequences of genetic circadian disruption induced by mutation or deletion of specific clock genes. Next, we evaluate experimental research into the effects of disruptive light/dark regimes, particularly light-phase shifts, dim ALAN, and constant light on the innate immune mechanisms under steady state and acute inflammation, and in the pathogenesis of common lifestyle diseases. We suggest that a better understanding of the mechanisms by which circadian disruption influences immune status can be of importance in the search for strategies to minimize the negative consequences of chronodisruption on health.

Association of outdoor artificial light at night with mental health among China adults: a prospective ecology study

Multiple environmental changes are related to mental disorders. However, research on the association between artificial light at night (ALAN) and mental health in China is limited, particularly at the national level. We used a "difference-in-differences" design and logistic regression to explore the relationship between ALAN changes and scores on self-assessed mental health. Participants were drawn from the China Family Panel Studies of adults in 2012 and 2018. The final analysis was based on 21,036 adults from 25 provinces throughout China. The brighter the ALAN, the worse was the mental health, and this connection was unaffected by particulate matter 2.5 (PM_2.5) or temperature. ALAN sensitivity may differ among populations. Our findings suggest that exposure to brighter ALAN is associated significantly with worse mental health among Chinese adults. Environmental policies that reduce ALAN could improve the mental health of the Chinese public.

Circadian Regulation of Hormonal Timing and the Pathophysiology of Circadian Dysregulation

Circadian rhythms are endogenously generated, daily patterns of behavior and physiology that are essential for optimal health and disease prevention. Disruptions to circadian timing are associated with a host of maladies, including metabolic disease and obesity, diabetes, heart disease, cancer, and mental health disturbances. The circadian timing system is hierarchically organized, with a master circadian clock located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks throughout the CNS and periphery. The SCN receives light information via a direct retinal pathway, synchronizing the master clock to environmental time. At the cellular level, circadian rhythms are ubiquitous, with rhythms generated by interlocking, autoregulatory transcription-translation feedback loops. At the level of the SCN, tight cellular coupling maintains rhythms even in the absence of environmental input. The SCN, in turn, communicates timing information via the autonomic nervous system and hormonal signaling. This signaling couples individual cellular oscillators at the tissue level in extra-SCN brain loci and the periphery and synchronizes subordinate clocks to external time. In the modern world, circadian disruption is widespread due to limited exposure to sunlight during the day, exposure to artificial light at night, and widespread use of light-emitting electronic devices, likely contributing to an increase in the prevalence, and the progression, of a host of disease states. The present overview focuses on the circadian control of endocrine secretions, the significance of rhythms within key endocrine axes for typical, homeostatic functioning, and implications for health and disease when dysregulated. © 2022 American Physiological Society. Compr Physiol 12: 1-30, 2022.

Light pollution spatial impact assessment in Hong Kong: Measurement and numerical modelling on commercial lights at street level

With rapid urbanization, the use of external lighting to illuminate cities for night-time activity is on the rise worldwide. Many studies have suggested the excessive use of external lighting causes light pollution, which harms human health and leads to energy wastage. Although more awareness has been raised, there are not many regulations and guidelines available. As one of the cities most affected by light pollution in the world, Hong Kong has started exploring this issue within the general and business communities. However, studies that quantitatively evaluate the problem of light pollution in this city are lacking. This study aimed to assess light pollution quantitatively through measurement and numerical modelling. To achieve this, measurement protocols were developed, and site measurements were carried out in one of the known problem areas, Sai Yeung Choi Street in Mong Kok district. Through this exercise, both vertical and horizontal illuminances on the street level and the light distribution along the street were determined. An average level of 250 lx for the vertical illuminance was found, which was 3-4 times higher than the recommended brightness for normal activity. The light environment of the measured area was also modelled with the simulation program DIALux. This effort complemented the measurements by providing a means to increase the resolution on the light variation and to visualize light pollution in a 3D environment. The simulation results were verified by correlating the numerical model with measurements. The correlated model was exercised in a subsequent sensitivity study to predict possible outcomes with changing lighting pattern and lighting lumen level. This study serves to quantify this issue, which helps with the further development of effective solutions.

Artificial light at night and risk of mental disorders: A systematic review

BACKGROUND

Emerging evidence suggests a possible association between artificial light at night (LAN) exposure and physiological and behavioral changes, with implications on mood and mental health. Due to the increased amount of individuals' LAN exposure, concerns have been raised regarding harmful impact of light pollution on mental health at the population level.

AIM

To perform a systematic review of observational studies to investigate if light at night, assessed both indoor and outdoor, may be associated with an increased risk of mental diseases in humans.

METHODS

We reviewed the epidemiological evidence on the association between LAN exposure, assessed either via satellite photometry or via measurements of bedroom brightness, and mental disorders. We systematically searched the PubMed, Embase and Web of Science databases up to April 1, 2022. Studies were included if they assessed the link between indoor or outdoor artificial light at night and one or more mental disorders in human populations.

RESULTS

Nine eligible studies were included in this review: six studies had a cross-sectional design, two had a longitudinal design with a median follow-up of 24 months, and one was a case-cohort study. Overall, we found moderate evidence of a positive association between LAN exposure and depressive symptoms and to a lesser extent other mental disorders, though the number of studies was limited and potential residual confounding such as socioeconomic factors, noise, or air pollution may have influenced the results.

CONCLUSIONS

Although more robust evidence is needed, the epidemiological evidence produced so far seems to support an association between LAN and risk of depressive disorders.

Selective blue-filtering spectacle lens protected primary porcine RPE cells against light emitting diode-induced cell damage

This study aimed to investigate whether use of a selective-blue-filtering (S-BF) lens can protect cultured primary porcine RPE cells against photo-irradiation. Transmittance of S-BF and UV-filtering (UVF) lenses was characterised spectrophotometrically. RPE cells were exposed to 1700 lux of white (peak λ at 443 and 533 nm; 0.44 mW/cm²) or blue (peak λ at 448 and 523 nm; 0.85 mW/cm²) LED light for 16 h to evaluate the influence of light source on the culture. The effect of the S-BF and UVF ophthalmic lenses on RPE cell cultures under blue light irradiation was then investigated. Cell viability was compared using trypan blue and MTT assays. Intracellular ROS production was detected by a fluorescein probe CM-H2DCFDA. Expression levels of catalase and Prdx3 were analysed by western blot. Trypan blue staining showed blue light caused more cell death than no light (p = 0.001) or white light (p = 0.005). MTT assay supported the hypothesis that exposure to blue light damaged RPE cells more severely than no light (p = 0.002) or white light (p = 0.014). Under blue light, use of the S-BF lens, which blocked 17% more blue light than the UVF lens, resulted in higher cellular viability (S-BF: 93.4±1.4% vs UVF: 90.6±1.4%; p = 0.022; MTT: 1.2-fold; p = 0.029). Blue and white light both significantly increased ROS production. The S-BF lens protected cells, resulting in lower levels of ROS and higher expression of catalase and Prdx3. To conclude, blue LED light exposure resulted in significant cytotoxicity to RPE cells. Partial blockage of blue light by an S-BF lens led to protective effects against retinal phototoxicity, which were mediated by reduction of ROS and increased levels of antioxidant enzymes.

Effects of morning and evening exposures to blue light of varying illuminance on ocular growth rates and ocular rhythms in chicks

Recent evidence indicates that moderate levels of blue light are sufficient to suppress the nighttime rise in serum melatonin in humans, suggesting that luminous screens may be deleterious to sleep cycles and to other functions. Little is known however, about the effects of exposures to blue light on ocular physiology. We tested the effects of transient blue light exposures of various illuminances on ocular growth rates and ocular rhythms in chicks. 10-day old chicks were exposed to narrow band blue light (460 nm) of specific illuminance for 4 h in the evening (ZT8-ZT12) or the morning (ZT0-ZT4) for 9 days; for the remainder of the day they were in white light (588 lux). For the evening, four illuminances were tested: 0.15 lux (n = 15), 200 lux (radiometrically matched to white controls; n = 16), 600 lux (photometrically matched to white controls; n = 15) or 1000 lux (n = 8). The 600 lux condition was also tested using a 2-h duration (n = 8). The 200 and 600 lux conditions were extended to 14 and 21 days (n = 8 each). For morning exposures, 200 lux (n = 9), 600 lux (n = 9) and 1000 lux (n = 8) were tested. Controls remained in white light (n = 23). Ocular dimensions were measured by A-scan ultrasonography on days 1 and 9 to assess growth rates. On day 8 or 9, measurements were made at 6-h intervals over 24 h starting at noon to assess rhythm parameters. Evening exposure to blue light stimulated ocular growth rates relative to controls for all except the bright condition (0.15 lux, 200 lux, 600 lux vs bright and white respectively: 845 μm, 838 μm, 898 μm vs 733 μm and 766 μm; p < 0.05 for all comparisons). 2 h exposures to 600 lux were similarly effective (915 μm vs 766 μm; p < 0.05). Morning exposures only resulted in growth stimulation for the 200 lux condition (200 lux vs white: 884 μm vs 766 μm; p < 0.05). Furthermore, for this group only, growth of the anterior chamber had a significant contribution to the overall effect (vs white: p < 0.05), and choroids showed significant thickening. For evening exposures to 200 and 600 lux, the growth stimulatory effect lasted for 14 days (p = 0.01); by 21 days only the 600 lux group still differed (p < 0.0001). Evening exposures caused circadian disruptions in the choroidal thickness rhythms, and morning exposures disrupted both axial and choroidal rhythms. Exposure to 4 h of blue light at lower illuminances (less than 1000 lux) at transition times of lights-on and lights-off stimulates ocular growth rates and affects ocular rhythms in chicks, suggesting that such exposures may be deleterious to emmetropization in children.

Impact of Thermal Dissipation on the Lighting Performance and Useful Life of LED Luminaires Applied to Urban Lighting: A Case Study

Currently, LED technology is an established form of lighting in our cities and homes. Its lighting performance, durability, energy efficiency and light, together with the economic savings that its use implies, are displacing other classic forms of lighting. However, some problems associated with the durability of the equipment related to the problems of thermal dissipation and high temperature have begun to be detected, which end up affecting their luminous intensity and the useful life. There are many studies that show a direct relationship between the low quality of LED lighting and the aging of the equipment or its overheating, observing the depreciation of the intensity of the light and the visual chromaticity performance that can affect the health of users by altering circadian rhythms. On the other hand, the shortened useful life of the luminaires due to thermal stress has a direct impact on the LCA (Life Cycle Analysis) and its environmental impact, which indirectly affects human health. The purpose of this article is to compare the results previously obtained, at different contour temperatures, by theoretical thermal simulation of the 3D model of LED street lighting luminaires through the ANSYS Fluent simulation software. Contrasting these results with the practical results obtained with a thermal imaging camera, the study shows how the phenomenon of thermal dissipation plays a fundamental role in the lighting performance of LED technology. The parameter studied in this work is junction temperature (T_j), and how it can be used to predict the luminous properties in the design phase of luminaires in order to increase their useful life.

Spectrophotometric properties of commercially available blue blockers across multiple lighting conditions

Lenses that filter short-wavelength ("blue") light are commercially marketed to improve sleep and circadian health. Despite their widespread use, minimal data are available regarding their comparative efficacy in curtailing blue light exposure while maintaining visibility. Fifty commercial lenses were evaluated using five light sources: a blue LED array, a computer tablet display, an incandescent lamp, a fluorescent overhead luminaire, and sunlight. Absolute irradiance was measured at baseline and for each lens across the visual spectrum (380-780 nm), which allowed calculation of percent transmission. Transmission specificity was also calculated to determine whether light transmission was predominantly circadian-proficient (455-560 nm) or non-proficient (380-454 nm and 561-780 nm). Lenses were grouped by tint and metrics were compared between groups. Red-tinted lenses exhibited the lowest transmission of circadian-proficient light, while reflective blue lenses had the highest transmission. Orange-tinted lenses transmitted similar circadian-proficient light as red-tinted lenses but transmitted more non-circadian-proficient light, resulting in higher transmission specificity. Orange-tinted lenses had the highest transmission specificity while limiting biologically active light exposure in ordinary lighting conditions. Glasses incorporating these lenses currently have the greatest potential to support circadian sleep-wake rhythms.

Current Insights into Optimal Lighting for Promoting Sleep and Circadian Health: Brighter Days and the Importance of Sunlight in the Built Environment

This perspective considers the possibility that daytime's intrusion into night made possible by electric lighting may not be as pernicious to sleep and circadian health as the encroachment of nighttime into day wrought by 20th century architectural practices that have left many people estranged from sunlight.

Disrupted Circadian Control of Hormonal Rhythms and Anticipatory Thirst by Dim Light at Night

AIMS

Our study addresses underlying mechanisms of disruption of the circadian timing system by low-intensity artificial light at night (ALAN), which is a growing global problem, associated with serious health consequences.

METHODS

Rats were exposed to low-intensity (∼2 lx) ALAN for 2 weeks. Using in situ hybridization, we assessed 24-h profiles of clock and clock-controlled genes in the suprachiasmatic nuclei (SCN) and other hypothalamic regions, which receive input from the master clock. Moreover, we measured the daily rhythms of hormones within the main neuroendocrine axes as well as the detailed daily pattern of feeding and drinking behavior in metabolic cages.

RESULTS

ALAN strongly suppressed the molecular clockwork in the SCN, as indicated by the suppressed rhythmicity in the clock (Per1, Per2, and Nr1d1) and clock output (arginine vasopressin) genes. ALAN disturbed rhythmic Per1 expression in the paraventricular and dorsomedial hypothalamic nuclei, which convey the circadian signals from the master clock to endocrine and behavioral rhythms. Disruption of hormonal output pathways was manifested by the suppressed and phase-advanced corticosterone rhythm and lost daily variations in plasma melatonin, testosterone, and vasopressin. Importantly, ALAN altered the daily profile in food and water intake and eliminated the clock-controlled surge of drinking 2 h prior to the onset of the rest period, indicating disturbed circadian control of anticipatory thirst and fluid balance during sleep.

CONCLUSION

Our findings highlight compromised time-keeping function of the central clock and multiple circadian outputs, through which ALAN disturbs the temporal organization of physiology and behavior.

A longitudinal study of morning, evening, and night light intensities and nocturnal sleep quality in a working population

We aimed to investigate whether higher light intensity in the morning is associated with better nocturnal sleep quality and whether higher light intensities in the evening or night have the opposite effect. Light intensity was recorded for 7 consecutive days across the year among 317 indoor and outdoor daytime workers in Denmark (55-56° N) equipped with a personal light recorder. Participants reported sleep quality after each nocturnal sleep. Sleep quality was measured using three parameters; disturbed sleep index, awakening index, and sleep onset latency. Associations between increasing light intensities and sleep quality were analyzed using mixed effects models with participant identity as a random effect. Overall, neither white nor blue light intensities during morning, evening, or night were associated with sleep quality, awakening, or sleep onset latency of the subsequent nocturnal sleep. However, secondary analyses suggested that artificial light during the morning and day contrary to solar light may increase vulnerability to evening light exposure. Altogether, we were not able to confirm that higher morning light intensity significantly improves self-reported sleep quality or that higher evening or night light intensities impair self-reported sleep quality at exposure levels encountered during daily life in a working population in Denmark. This suggests that light intensities alone are not important for sleep quality to a degree that it is distinguishable from other important parameters in daily life settings.

Reviewing the Role of Outdoor Lighting in Achieving Sustainable Development Goals

The Sustainable Development Goals (SDGs) aim at providing a healthier planet for present and future generations. At the most recent SDG summit held in 2019, Member States recognized that the achievements accomplished to date have been insufficient to achieve this mission. This paper presents a comprehensive literature review of 227 documents contextualizing outdoor lighting with SDGs, showing its potential to resolve some existing issues related to the SDG targets. From a list of 17 goals, six SDGs were identified to have relevant synergies with outdoor lighting in smart cities, including SDG 3 (Good health and well-being), SDG 11 (Sustainable cities and communities), SDG 14 (Life below water) and SDG 15 (Life on land). This review also links efficient lighting roles partially with SDG 7 (Affordable and clean energy) and SDG 13 (Climate action) through Target 7.3 and Target 13.2, respectively. This paper identifies outdoor lighting as a vector directly impacting 16 of the 50 targets in the six SDGs involved. Each section in this review discusses the main aspects of outdoor lighting by a human-centric, energy efficiency and environmental impacts. Each aspect addresses the most recent studies contributing to lighting solutions in the literature, helping us to understand the positive and negative impacts of artificial lighting on living beings. In addition, the work summarizes the proposed solutions and results tackling specific topics impacting SDG demands.

Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources

Sky Quality Meter (SQM) is a commercial instrument based on photometers widely used by amateur astronomers for skyglow measurement from the ground. In the framework of the MINLU project, two SQM-LE units were integrated in an autonomous sensor suite realized and tested at University of Padova for monitoring light pollution from drones or sounding balloons. During the ground tests campaign before airborne measurement, the performance of both SQM units was verified in laboratory using controlled light sources as a reference input; the results showed that both units presented an angular response deviating consistently from the expected performance and that the sensors' field of view was larger than the one declared in the manufacturer's datasheet. This aspect in particular would affect direct skyglow measurements during flight as light sources close to the boundaries of the field of view would not be attenuated but instead detected by the sensors. As a direct consequence, the measurement of low-intensity skyglows at stratospheric altitudes could be affected by high-intensity punctual sources acting as lateral disturbances. A dedicated test campaign was therefore conceived and realized to investigate SQM unit response to light sources in the field of view and identify the true angular response curve; the setup consisted in a controlled rotatory stage moving the unit in front of a fixed diffusive light source. Different test conditions were used to validate the experimental procedure, demonstrating the repeatability of the measurements. This paper presents the experimental campaign and the resulting SQM angular response curve; results indicate for both SQMs a larger than expected field of view and the presence of a double peak in the angular response, which is likely related to a non-perfect alignment of SQMs collimation optics. Furthermore, the wider resulting curves suggest that the contribution of lateral sources is more prominent with respect to the response predicted by the manufacturer. For this reason, the utilization of baffles to restrict SQMs field of view is analyzed to minimize the disturbance of lateral light sources and two different geometries are presented.

Sleep Interventions in the Treatment of Schizophrenia and Bipolar Disorder

Due to the effects of sleep on the central nervous system, it is thought that sleep disorders have a special importance in the onset, course and treatment of psychiatric diseases. Although the negative effects of sleep problems on the occurrence, recurrence and clinical course of psychiatric disorders are well known, it is reported that clinicians do not spend enough time for sleep problems in practice. This may be related to the fact that patients underreport their complaints for various reasons, insufficient examination time, and clinicians' lack of knowledge about the importance of the subject. Pharmacotherapy, psychological and behavioral interventions are options among the therapeutic approaches to sleep problems. But, it seems that clinicians tend to prefer pharmacological approaches for the treatment of sleep problems. However, it is important to choose the appropriate treatment option with considering the method preferred by the patients, who already use many and high doses of pharmacological agents, the nature of the psychiatric disorder and the sleep problem. In this context, chronotherapeutic approaches such as bright light, sleep deprivation, interpersonal relations and social rhythm therapy, and cognitive behavioral therapy techniques adapted for patients with bipolar disorder can be used in the treatment of suitable patients. In this article, the current literature about sleep-related problems observed in patients with schizophrenia and bipolar disorder is reviewed comprehensively with presenting clinical phenotypes and treatment approaches.

Ambient-task combined lighting to regulate autonomic and psychomotor arousal levels without compromising subjective comfort to lighting

Background

Although evidence of both beneficial and adverse biological effects of lighting has accumulated, biologically favorable lighting often does not match subjectively comfortable lighting. By controlling the correlated color temperature (CCT) of ambient lights, we investigated the feasibility of combined lighting that meets both biological requirements and subjective comfort.

Methods

Two types of combined lightings were compared; one consisted of a high-CCT (12000 K) light-emitting diode (LED) panel as the ambient light and a low-CCT (5000 K) LED stand light as the task light (high-low combined lighting), and the other consisted of a low-CCT (4500 K) LED panel as the ambient light and the same low-CCT (5000 K) stand light as the task light (low-low combined lighting) as control. Ten healthy subjects (5 young and 5 elderly) were exposed to the two types of lighting on separate days. Autonomic function by heart rate variability, psychomotor performances, and subjective comfort were compared.

Results

Both at sitting rest and during psychomotor workload, heart rate was higher and the parasympathetic index of heart rate variability was lower under the high-low combined lighting than the low-low combined lighting in both young and elderly subject groups. Increased psychomotor alertness in the elderly and improved sustainability of concentration work performance in both age groups were also observed under the high-low combined lighting. However, no significant difference was observed in the visual-analog-scale assessment of subjective comfort between the two types of lightings.

Conclusions

High-CCT ambient lighting, even when used in combination with low-CCT task lighting, could increase autonomic and psychomotor arousal levels without compromising subjective comfort. This finding suggests the feasibility of independent control of ambient and task lighting as a way to achieve both biological function regulation and subjective comfort.

Green light extends Drosophila longevity

The role of visible light on longevity is incompletely understood. Here we show the effect of visible light in Drosophila melanogaster is wavelength specific. Life span was significantly extended by green light, whereas blue light reduced longevity dramatically, and minor impact was observed with red light. While oxidative stress, heat stress, or caloric restriction does not contribute to the beneficial effect of green light, our study found that the life span extension effect of green light might be mediated by microbiota or photosensitive micronutrients in food medium. In conclusion, we report that green light can extend longevity and present the potential of light as a noninvasive therapy for aging-related diseases.

Association of Outdoor Artificial Light at Night With Mental Disorders and Sleep Patterns Among US Adolescents

IMPORTANCE

Indoor nighttime light exposure influences sleep and circadian rhythms and is known to affect mood-associated brain circuits in animals. However, little is known about the association between levels of nighttime outdoor light and sleep and mental health in the population, especially among adolescents.

OBJECTIVE

To estimate associations of outdoor artificial light at night (ALAN) with sleep patterns and past-year mental disorder among US adolescents.

DESIGN, SETTING, AND PARTICIPANTS

This population-based, cross-sectional study of US adolescents used the National Comorbidity Survey-Adolescent Supplement, a nationally representative cross-sectional survey conducted from February 2001 through January 2004. A probability sample of adolescents aged 13 to 18 years was included. Analyses were conducted between February 2019 and April 2020.

EXPOSURES

Levels of outdoor ALAN, measured by satellite, with means calculated within census block groups. ALAN values were transformed into units of radiance (nW/cm2/sr).

MAIN OUTCOMES AND MEASURES

Self-reported habitual sleep patterns (weeknight bedtime, weeknight sleep duration, weekend bedtime delay, and weekend oversleep) and past-year mood, anxiety, behavior, and substance use disorders, measured via an in-person structured diagnostic interview. Parent-reported information was included in behavior disorder diagnoses.

RESULTS

Among 10 123 adolescents (4953 boys [51.3%]; mean [SE] age, 15.2 [0.06] years [weighted]; 6483 for behavior disorder outcomes), ALAN was positively associated with indicators of social disadvantage, such as racial/ethnic minority status (median [IQR] ALAN: white adolescents, 12.96 [30.51] nW/cm2/sr; Hispanic adolescents: 38.54 [47.84] nW/cm2/sr; non-Hispanic black adolescents: 37.39 [51.88] nW/cm2/sr; adolescents of other races/ethnicities: 30.94 [49.93] nW/cm2/sr; P < .001) and lower family income (median [IQR] ALAN by family income-to-poverty ratio ≤1.5: 26.76 [52.48] nW/cm2/sr; >6: 21.46 [34.38] nW/cm2/sr; P = .005). After adjustment for several sociodemographic characteristics, as well as area-level population density and socioeconomic status, this study found that higher ALAN levels were associated with later weeknight bedtime, and those in the lowest quartile of ALAN reported the longest weeknight sleep duration. Those in the highest quartile of ALAN went to bed 29 (95% CI, 15-43) minutes later and reported 11 (95% CI, 19-2) fewer minutes of sleep than those in the lowest quartile. ALAN was also positively associated with prevalence of past-year mood and anxiety disorder: each median absolute deviation increase in ALAN was associated with 1.07 (95% CI, 1.00-1.14) times the odds of mood disorder and 1.10 (95% CI, 1.05-1.16) times the odds of anxiety disorder. Further analyses revealed associations with bipolar disorder (odds ratio [OR], 1.19 [95% CI, 1.05-1.35]), specific phobias (OR, 1.18 [95% CI, 1.11-1.26]), and major depressive disorder or dysthymia (OR, 1.07 [95% CI, 1.00-1.15]). Among adolescent girls, differences in weeknight bedtime by ALAN (third and fourth quartiles vs first quartile) were greater with increasing years since menarche (F3, 8.15; P < .001).

CONCLUSIONS AND RELEVANCE

In this study, area-level outdoor ALAN was associated with less favorable sleep patterns and mood and anxiety disorder in adolescents. Future studies should elucidate whether interventions to reduce exposure to ALAN may positively affect mental and sleep health.

Urbanicity mental costs valuation: a review and urban-societal planning consideration

Living in cities has numerous comparative advantages than living in the countryside or in small villages and towns, most notably better access to education, services and jobs. However, it is also associated with a roughly twofold increase in some mental disorders rate incidence compared with living in rural areas. Economic assessments reported a forecasted loss of more than 19 trillion dollars in global GDP between 2011 and 2030 and of around 7 trillion for the year 2030 alone when measured by the human capital method. If we exclude self-selection processes and make the hypothesis to be able to level down the mental illness rate incidence in urban areas to these of the rural by better urban-societal planning, around € 1.2 trillion could be saved yearly worldwide. Even a reduction of only 20% in urban mental illness rate would save around 250 billion dollars yearly.

Circadian Rhythms in Environmental Health Sciences

PURPOSE OF REVIEW

This review aims to explore how circadian rhythms influence disease susceptibility and potentially modify the effect of environmental exposures. We aimed to identify biomarkers commonly used in environmental health research that have also been the subject of chronobiology studies, in order to review circadian rhythms of relevance to environmental health and determine if time-of-day is an important factor to consider in environmental health studies. Moreover, we discuss opportunities for studying how environmental exposures may interact with circadian rhythms to structure disease pathology and etiology.

RECENT FINDINGS

In recent years, the study of circadian rhythms in mammals has flourished. Animal models revealed that all body tissues have circadian rhythms. In humans, circadian rhythms were also shown to exist at multiple levels of organization: molecular, cellular, and physiological processes, including responding to oxidative stress, cell trafficking, and sex hormone production, respectively. Together, these rhythms are an essential component of human physiology and can shape an individual's susceptibility and response to disease. Circadian rhythms are relatively unexplored in environmental health research. However, circadian clocks control many physiological and behavioral processes that impact exposure pathways and disease systems. We believe this review will motivate new studies of (i) the impact of exposures on circadian rhythms, (ii) how circadian rhythms modify the effect of environmental exposures, and (iii) how time-of-day impacts our ability to observe the body's response to exposure.

Quality of Sleep Among Bedtime Smartphone Users

Background

Exposure to light from viewing devices at night disturbs the circadian rhythm, especially sleep. The study aimed to assess (a) extent to which smart phones are used by medical undergraduate students during bedtime and to find their quality of sleep (b) the association of quality of sleep and cell phone variables.

Methods

A cross sectional observational study was conducted among 450 medical undergraduate students. The participants completed Pittsburgh Sleep Quality Index (PSQI) questionnaire and a validated semi structured questionnaire consisting of demographic details and cell phone variables.

Results

By dividing the subjects into three groups according to their usage (Group I <1 hour, Group II 1 to 2 hours, Group III >2 hours), Group III respondents had significant prolonged sleep latency, reduced sleep duration, sleep inefficiency and daytime sleep disturbances (P < 0.05). Lack of awareness about night shift mode, lying posture use while using phone during bedtime correlated with poor quality sleep (P < 0.05).

Conclusions

Awareness about the negative impact of evening exposure to viewing devices on sleep and health should be emphasized.

Visual Image Quality Impacts Circadian Rhythm-Related Gene Expression in Retina and in Choroid: A Potential Mechanism for Ametropias

Purpose

Stimulated by evidence implicating diurnal/circadian rhythms and light in refractive development, we studied the expression over 24 hours of selected clock and circadian rhythm-related genes in retina/retinal pigment epithelium (RPE) and choroid of experimental ametropias in chicks.

Methods

Newly hatched chicks, entrained to a 12-hour light/dark cycle for 12 to 14 days, either experienced nonrestricted vision OU (i.e., in both eyes) or received an image-blurring diffuser or a minus 10-diopter (D) or a plus 10-D defocusing lens over one eye. Starting 1 day later and at 4-hour intervals for 24 hours, the retina/RPE and choroid were separately dissected. Without pooling, total RNA was extracted, converted to cDNA, and assayed by quantitative PCR for the expression of the following genes: Opn4m, Clock, Npas2, Per3, Cry1, Arntl, and Mtnr1a.

Results

The expression of each gene in retina/RPE and in choroid of eyes with nonrestricted vision OU varied over 24 hours, with equal levels OU for most genes and times. Altered visual input influenced gene expression in complex patterns that varied by gene, visual input, time, and eye, affecting experimental eyes with altered vision and also contralateral eyes with nonrestricted vision.

Discussion

Altering visual input in ways known to induce ametropias alters the retinal/RPE and choroidal expression of circadian rhythm-related genes, further linking circadian biology with eye growth regulation. While further investigations are needed, studying circadian processes may help understand refractive mechanisms and the increasing myopia prevalence in contemporary societies where lighting patterns can desynchronize endogenous rhythms from the natural environmental light/dark cycle.

Light Exposure during Days with Night, Outdoor, and Indoor Work

OBJECTIVE

To assess light exposure during days with indoor, outdoor, and night work and days off work.

METHODS

Light intensity was continuously recorded for 7 days across the year among indoor (n = 170), outdoor (n = 151), and night workers (n = 188) in Denmark (55-56°N) equipped with a personal light recorder. White light intensity, duration above 80, 1000, and 2500 lux, and proportion of red, green, and blue light was depicted by time of the day and season for work days and days off work.

RESULTS

Indoor workers' average light exposure only intermittently exceeded 1000 lux during daytime working hours in summer and never in winter. During daytime working hours, most outdoor workers exceeded 2500 lux in summer and 1000 lux in winter. Night workers spent on average 10-50 min >80 lux when working night shifts. During days off work, indoor and night workers were exposed to higher light intensities than during work days and few differences were seen between indoor, outdoor, and night workers. The spectral composition of light was similar for indoor, outdoor, and night workers during days at and off work.

CONCLUSION

The night workers of this study were during night hours on average exposed for a limited time to light intensities expected to suppress melatonin. The indoor workers were exposed to light levels during daylight hours that may reduce general well-being and mood, especially in winter. Outdoor workers were during summer daylight hours exposed to light levels comparable to those used for the treatment of depression.

The effects of brief high intensity light on ocular growth in chicks developing myopia vary with time of day

Evidence suggests that the relevant variable in the anti-myopigenic effect of increased time spent outdoors is the increase in light intensity. Because light is the strongest Zeitgeber, it is plausible that the effects of bright light exposure depend on time of day, and may impact circadian rhythms. In these studies, we asked whether the effects on eye growth rates and ocular rhythms of brief daily exposures to bright light differed depending on time of day in eyes developing myopia in response to form deprivation (FD) or negative lens-induced hyperopic defocus (LENS). We also studied the effects of concurrent exposures to brief hyperopic defocus and bright light. Exp. 1: Starting at 12d, chicks wearing monocular diffusers or -10 D lenses were exposed to 3 daily hours (h) of bright light (30K lux) in the morning (FD: n = 12; LENS: n = 7) or evening (FD: n = 21; LENS: n = 7) for a total of 6 exposures. Controls wore diffusers or lenses but weren't exposed to bright light ("not bright" FD: n = 14; LENS: n = 9). Exp. 2: Untreated chicks were exposed to 3 h bright light in the morning (n = 12) or evening (n = 14) for a total of 6 exposures. Controls were not exposed to bright light (n = 11). Exp. 3: Chicks were exposed to 2 h simultaneous monocular hyperopic defocus and bright light in the morning (n = 11), mid-day (n = 7) or evening (n = 8) for 5 exposures. "Not bright" lens-wearing controls were data from published work (Nickla et al., 2017). High frequency A-scan ultrasonography was done at the start and end to measure growth rates. The FD group in Exp. 1 and the morning and evening groups in Exp. 3 were measured at 6-h intervals over the final 24 h to determine parameters for the rhythms in axial length and choroidal thickness. 1. Brief bright light in the evening inhibited eye growth in eyes wearing diffusers or lenses relative to "not bright" controls(interocular differences: FD: 316 vs 468 μm, p = 0.026; LENS: 233 vs 438 μm, p = 0.03); morning bright light had no effect. There was no differential effect of time of day of exposure on the rhythm in axial length; for choroid thickness, "time" accounted for the variance between groups (2-way ANOVA interaction p = 0.027). 2. In binocularly untreated chicks, bright light in the morning had a small but significant growth stimulatory effect relative to evening exposures (803  vs 679 μm/7d; post-hoc p = 0.048). 3. Eyes exposed to simultaneous hyperopic defocus and bright light were significantly more inhibited relative to "not bright" controls for morning exposures (interocular differences: -207 vs 69 μm; p < 0.01). In conclusion, the effects of brief periods of bright light on the growth controller depended on the time of day of exposure and on the contemporaneous state ofocular growth .

Difference in autonomic nervous effect of blue light depending on the angle of incidence on the eye

Objective

Blue light has been attributed to the adverse biological effects caused by the use of smartphones and tablet devices at night. However, it is not realistic to immediately avoid nighttime exposure to blue light in the lifestyle of modern society, so other effective methods should be investigated. Earlier studies reported that inferior retinal light exposure causes greater melatonin suppression than superior retinal exposure. We examined whether the autonomic responses to blue light depends on the angle of incidence to the eye.

Results

In eight healthy subjects, blue light from organic electroluminescent lighting device (15.4 lx at subjects’ eye) was exposed from 6 angles (0º, 30º, 45º, 135º, 150º, and 180º) for 5 min each with a 10-min interval of darkness. After adjusting the order effect of angles, however, no significant difference in heart rate or autonomic indices of heart rate variability with the angle of incidence was detected in this study.

Chromaticity-based real-time assessment of melanopic and luminous efficiency of smartphone displays

We investigate the spectral power distributions of 54 phones (33 measured experimentally in default text mode and 21 downloaded from the web) and estimate the mean ± std. dev. of the luminous efficiency of radiation, melanopic efficiency of radiation, and melanopic/photopic ratio as 287 ± 13 lm/W, 303 ± 26 blm/W, and 1.06 ± 0.13, respectively. We establish the chromaticity-performance characteristics relation to precisely assess the action efficiency of radiation performance using either RGB gray values or CIE xy values. Our real-time assessment of smartphone displays can aid in reducing energy consumption and improving user health.

Influence of a Light Source Installed in a Luminaire of Opal Sphere Type on the Effect of Light Pollution

The article presents the results of the studies concerning the influence of a light source installed in luminaire of opal sphere type on the light pollution effect of the night sky. It is known from literature reports that the effect of light pollution is influenced by the spectral distribution of light. Although the influence of the spectral distribution has been widely studied from different perspectives, there is still a need to study this phenomenon—for example, from the point of view of the spectral reflection properties of the ground, on which the lanterns are installed. Hence, the above-mentioned aspect was considered in the authors’ investigations. The luminaire considered has been equipped with 20 different light sources, including the latest generation of lamps (light-emitting diodes, LEDs) as well as the conventional ones. With respect to these light sources, the measurements of light distribution and spectral distribution of emitted radiation of the luminaire were performed. Having these measurement data, the simulations were carried out using the DIALux software, and the calculations were made using the specially prepared calculation tool. On the basis of the results obtained in this way this was stated that the type of light source installed in the luminaire has a significant effect on the sky glow. An important factor affecting light pollution is not only the value of the luminous flux emitted upward but also the spectral characteristics of the emitted radiation, the impact of which is most noticeable. The conclusions from the studies indicate the next steps in the analysis of the light pollution effect. These steps will be focused on extended analysis of LEDs as modern and developed light sources.

Effect of duration, and temporal modulation, of monochromatic light on emmetropization in chicks

Previous experiments disagree on the effect of monochromatic light on emmetropization. Some species respond to wavelength defocus created by longitudinal chromatic aberration and become more myopic in monochromatic red light and more hyperopic in monochromatic blue light, while other species do not. Using the chicken model, we studied the effect of the duration of light exposure, modes of lighting, and circadian interruption on emmetropization in monochromatic light. To achieve this goal, we exposed one-week-old chicks to flickering or steady monochromatic red or blue light for a short (10 days) or long (17 days) duration; other chicks were exposed to white light for 10 days. Refraction and ocular biometry were measured. Activity was measured via a motion detection algorithm and an IR camera. The results showed that in both steady and flickering light, there was a greater increase in axial length and vitreous chamber depth in chicks exposed to red or white light compared to chicks exposed to blue light. With a longer duration of exposure, axial length and vitreous chamber depth differences were no longer observed, except at an intermediate time point. Chicks exposed to red light were more active during the day compared to chicks exposed to blue light. We conclude that our results indicate that with short duration monochromatic light exposure, chicks rely on wavelength defocus to guide emmetropization. With longer exposure from hatching, our results support the notion that responses to wavelength defocus can be transient and that the difference between species may be due to differences in experimental duration and/or interference with circadian activity rhythms.

Effects of Lighting Quality on Working Efficiency of Workers in Office Building in Tanzania

Background

In this era of Information Communication Technology, a high-quality working environment is essential to the occupants. Providing quantity rather the quality of work environments is very common in most of the least developed countries, including Tanzania. Existing research asserts that poor indoor environmental quality such as lighting has a detrimental effect on human health, and in case of the office working population, it also affects their work performance. This study aims to analyze the effects of the lighting quality on working efficiency of workers in Tanzania.

Methods

Four representative offices from the administration building at Mbeya University of Science and Technology were investigated from June to September 2018. The customized questionnaire survey tool was administered to the randomly selected occupants to survey their perceptions about the quality of lighting in their workplace and its influence on their health and work efficiency. Physical observation and illuminance distribution measurements were also conducted.

Results

The statistical analysis indicates that the majority of the occupants are less satisfied with the lighting quality in their working environment, and some respondents reported that it significantly affected their work efficiency and wellbeing. The average desk illuminance and uniformity level were found to be below the recommended values of the Chartered Institution of Building Services Engineers (CIBSE) and the International Commission on lighting (CIE).

Conclusion

Despite the suggested improvement measures, this research emphasizes that poorly articulated work environment can adversely affect the productivity and work efficiency of the workers. The workers in such condition are also exposed to occupational diseases. Thus, providing a healthy work environment should be a fundamental right of the workers.

Effect on nurse and patient experience: overnight use of blue-depleted illumination

BACKGROUND

Typical hospital lighting is rich in blue-wavelength emission, which can create unwanted circadian disruption in patients when exposed at night. Despite a growing body of evidence regarding the effects of poor sleep on health outcomes, physiologically neutral technologies have not been widely implemented in the US healthcare system.

OBJECTIVE

The authors sought to determine if rechargeable, proximity-sensing, blue-depleted lighting pods that provide wireless task lighting can make overnight hospital care more efficient for providers and less disruptive to patients.

DESIGN

Non-randomised, controlled interventional trial in an intermediate-acuity unit at a large urban medical centre.

METHODS

Night-time healthcare providers abstained from turning on overhead patient room lighting in favour of a physiologically neutral lighting device. 33 nurses caring for patients on that unit were surveyed after each shift. 21 patients were evaluated after two nights with standard-of-care light and after two nights with lighting intervention.

RESULTS

Providers reported a satisfaction score of 8 out of 10, with 82% responding that the lighting pods provided adequate lighting for overnight care tasks. Among patients, a median 2-point improvement on the Hospital Anxiety and Depression Scale was reported.

CONCLUSION AND RELEVANCE

The authors noted improved caregiver satisfaction and decreased patient anxiety by using a blue-depleted automated task-lighting alternative to overhead room lights. Larger studies are needed to determine the impact of these lighting devices on sleep measures and patient health outcomes like delirium. With the shift to patient-centred financial incentives and emphasis on patient experience, this study points to the feasibility of a physiologically targeted solution for overnight task lighting in healthcare environments.

Effects of light on aging and longevity

Increasing evidence suggests an important role for light in regulation of aging and longevity. UV radiation is a mutagen that can promote aging and decrease longevity. In contrast, NIR light has shown protective effects in animal disease models. In invertebrates, visible light can shorten or extend lifespan, depending on the intensity and wavelength composition. Visible light also impacts human health, including retina function, sleep, cancer and psychiatric disorders. Possible mechanisms of visible light include: controlling circadian rhythms, inducing oxidative stress, and acting through the retina to affect neuronal circuits and systems. Changes in artificial lighting (e.g., LEDs) may have implications for human health. It will be important to further explore the mechanisms of how light affects aging and longevity, and how light affects human health.

Altered ocular parameters from circadian clock gene disruptions

The pathophysiology of refractive errors is poorly understood. Myopia (nearsightedness) in particular both blurs vision and predisposes the eye to many blinding diseases during adulthood. Based on past findings of diurnal variations in the dimensions of the eyes of humans and other vertebrates, altered diurnal rhythms of these ocular dimensions with experimentally induced myopia, and evolving evidence that ambient light exposures influence refractive development, we assessed whether disturbances in circadian signals might alter the refractive development of the eye. In mice, retinal-specific knockout of the clock gene Bmal1 induces myopia and elongates the vitreous chamber, the optical compartment separating the lens and the retina. These alterations simulate common ocular findings in clinical myopia. In Drosophila melanogaster, knockouts of the clock genes cycle or period lengthen the pseudocone, the optical component of the ommatidium that separates the facet lens from the photoreceptors. Disrupting circadian signaling thus alters optical development of the eye in widely separated species. We propose that mechanisms of myopia include circadian dysregulation, a frequent occurrence in modern societies where myopia also is both highly prevalent and increasing at alarming rates. Addressing circadian dysregulation may improve understanding of the pathogenesis of refractive errors and introduce novel therapeutic approaches to ameliorate myopia development in children.

Effects of the Emitted Light Spectrum of Liquid Crystal Displays on Light-Induced Retinal Photoreceptor Cell Damage

Liquid crystal displays (LCDs) are used as screens in consumer electronics and are indispensable in the modern era of computing. LCDs utilize light-emitting diodes (LEDs) as backlight modules and emit high levels of blue light, which may cause retinal photoreceptor cell damage. However, traditional blue light filters may decrease the luminance of light and reduce visual quality. We adjusted the emitted light spectrum of LED backlight modules in LCDs and reduced the energy emission but maintained the luminance. The 661W photoreceptor cell line was used as the model system. We established a formula of the ocular energy exposure index (OEEI), which could be used as the indicator of LCD energy emission. Cell viability decreased and apoptosis increased significantly after exposure to LCDs with higher emitted energy. Cell damage occurred through the induction of oxidative stress and mitochondrial dysfunction. The molecular mechanisms included activation of the NF-κB pathway and upregulation of the expression of proteins associated with inflammation and apoptosis. The effect was correlated with OEEI intensity. We demonstrated that LCD exposure-induced photoreceptor damage was correlated with LCD energy emission. LCDs with lower energy emission may, therefore, serve as suitable screens to prevent light-induced retinal damage and protect consumers’ eye health.

LED Light Sources and Their Complex Set-Up for Visually and Biologically Effective Illumination for Ornamental Indoor Plants

Ornamental plants are often used in indoor environments as part of biophilic design to improve the health and wellbeing of occupants, and to support sustainable, green architecture. Unfortunately, many plants do not thrive and need to be continuously replaced, which is economically unsustainable. The wavelengths and spectrum ratio of commonly used light sources such as light emitting diode (LED), and the lack of an appropriate light dark cycle (photoperiod), appear to be crucial influencing factors. Therefore, this study focuses on determining the optimal action spectrum of LEDs for visually and biologically effective illumination for plants, and humans as end users. This practice-based research study applies critical analysis of literature, photographic evaluation of the appearance of plants under various LED lighting in the form of a visual assessment questionnaire-based survey, and provides various measurements that record the properties of light including correlated color temperature (CCT), color rendering index (CRI), spectral power distribution (SPD), peak light wavelength (λP), photosynthetic photon flux density (PPFD) and daily light integrals (DLI). Research confirms the LED lighting used for horticultural food production cannot be applied to ornamental indoor plants due to fundamental differences in purpose. Such illumination provides fast growth for market consumption and usually makes plants appear unnatural, whereas ornamental plants in an indoor environment should grow at an appropriate speed which reduces maintenance costs and they should have a natural appearance. These new findings, supported by evidence and data, can help investors, clients, architects, landscape and lighting designers, as well as luminaire manufacturers, make improved, biophilic-sustainable lighting design choices.

Urban-Rural Differences in Older Adult Depression: A Systematic Review and Meta-analysis of Comparative Studies

CONTEXT

Depression among older adults (aged 60 years or older) is a problem that could be exacerbated by global trends in urbanization and population aging. The study purpose was to assess whether urban, relative to rural, residence is associated with depression among older adults and whether associations differ in countries with developed versus developing economies.

EVIDENCE ACQUISITION

In 2017, the authors identified and extracted information from comparative studies of urban-rural depression prevalence among older adults. Studies were identified in PubMed, PsychINFO, and Web of Science and limited to English language articles published after 1985. Eighteen studies met inclusion criteria. Random effects meta-analysis was conducted to produce weighted pooled ORs estimating the association between urban-rural residence and depression for all study participants (N=31,598) and sub-analyses were conducted for developed (n=12,728) and developing (n=18,870) countries.

EVIDENCE SYNTHESIS

Depression prevalence was significantly higher among urban residents in ten studies and significantly higher among rural residents in three studies (all three conducted in China). Associations between urban-rural residence and depression generally remained significant after adjusting for covariates. In developed countries, the odds of depression were significantly higher among urban than rural residents (pooled OR=1.44, 95% CI=1.10, 1.88). However, in developing countries, this association was not observed (pooled OR=0.91, 95% CI=0.46, 1.77).

CONCLUSIONS

Converging trends of urbanization and population aging could increase the global burden of depression among older adults. The pathways through which urban-rural residence influences depression risk among older adults might differ by country context. Future research should focus on measuring variation in these contexts.

Circadian Control of Neuroendocrine Function: Implications for Health and Disease

The circadian timing system orchestrates daily rhythms in physiology and behavior via the suprachiasmatic nucleus (SCN), the master brain clock. Because endocrine secretions have far-reaching influence on the brain and periphery, circadian regulation of hormones is essential for normal functioning and disruptions to circadian timing (e.g., irregular sleep patterns, limited exposure to sunlight, jet lag, nighttime light exposure) have detrimental health consequences. Herein, we provide an overview of circadian timing in three major endocrine axes, the hypothalamo-pituitary-gonadal (HPG), hypothalamo-pituitary-adrenal (HPA) and hypothalamo-pituitary-thyroid (HPT) axes, and then consider the negative health consequences of circadian disruptions in each of these systems. For example, disruptions to HPG axis circadian timing lead to a host of negative reproductive outcomes such as irregular menstrual cycles, low sperm density and increased rates of miscarriages and infertility. Dysregulation of HPA axis timing is associated with obesity and metabolic disease, whereas disruptions to the HPT axis are associated with dysregulated metabolic gene rhythms in the heart. Together, this overview underscores the significance of circadian endocrine rhythms in normal health and disease prevention.