Outdoor Light Exposure Research Articles

Sleep patterns in Metropolitan and Regional areas in Japan: Before and during COVID-19 social restrictions

ABSTRACT Sleep timing is an important output of the circadian system. The COVID-19-mandated social restrictions significantly altered commuting time and sleep duration regionally in Japan. This study aimed to elucidate sleep patterns, especially chronotype and social jetlag (SJL), due to changes in social time pressure through the social restrictions between the Metropolitan and Regional areas in Japan. As part of the Global Chrono Corona Survey 2020 (GCCS), the data were collected during social restrictions (SR), but pre-COVID-19 behaviours were also queried retrospectively. We analyzed a cohort of 729 respondents representing both the Metropolitan and the Regional areas separately for workdays and work-free days. While the areas showed no difference in SJL before SR, the differential decrease was larger in the Metropolitan area during SR, resulting in a significant difference in SJL between the areas. The outdoor light exposure before SR was 30 min longer in the Metropolitan areas than in the Regional; during SR both areas showed similarly low (below 1 h) outdoor light exposures. The variables associated with decreased SJL were the Metropolitan areas, work-from-home, a no-usage alarm clock on workdays, and chronotypes (mid-sleep time on free days corrected for sleep deficit accumulated over the workweek, MSFsc) during SR. The results suggest that relaxed social schedules, as reflected in the increased frequency of work-from-home and reduced alarm clock use, and moving towards earlier MSFsc during SR were linked to decreased SJL and were more prominent in the Metropolitan areas. This study provides insights into sleep patterns and the social time pressure markers, by comparison between residential groups in Japan.

Towards a better understanding of light-glucose induced modifications on the structure and biological activity of formulated Nivolumab

In the last years, monoclonal antibodies (mAbs) have rapidly escalated as biopharmaceuticals into cancer treatments, mainly for their target specificity accompanied by less side effects than the traditional chemotherapy, and stimulation of reliable long-term anti-tumoral responses. They are potentially unstable macromolecules under shaking, temperature fluctuations, humidity, and indoor and outdoor light exposure, all stressors occurring throughout their production, transport, storage, handling, and administration steps. The chemical and physical modifications of mAbs can lead not only to the loss of their bioactivity, but also to the enhancement of their immunogenicity with increasing risk of severe hypersensitivity reactions in treated patients because of aggregation. The photostability of Nivolumab, the active principle of Opdivo®, has been here studied. The chemical modifications detected by LC-MS/MS after the light stressor showed Trp and Met mono and double oxidations as primary damage induced by light on this mAb. The oxidations were stronger when the mAb was diluted in sterile glucose solution where 5-HMF, a major heat glucose degradation product, acted as singlet oxygen producer under irradiation. However, no significant changes in the mAb conformation were found. On the contrary, formation of a significant extent of aggregates has been detected after shining high simulated sunlight doses. This again took place particularly when Nivolumab was diluted in sterile glucose, thus raising a direct correlation between the aggregation and the oxidative processes. Finally, the biological activity under light stress assessed by a blockade assay test demonstrated the maintenance of the PD-1 target recognition even under high light doses and in glucose solution, in line with the preservation of the secondary and tertiary structures of the mAb. Based on our results, as sterile glucose is mostly used for children's therapies, special warnings, and precautions for healthcare professionals should be included for their use to the pediatric population.

Self-Reported Outdoor Light Exposure Time and Incident Heart Failure.

A healthy lifestyle is an important factor for preventing heart failure. However, the association between outdoor light exposure time and heart failure is still unknown. The aim of this study was to examine the association between outdoor light exposure time and the incidence of heart failure. This cohort study included participants from the UK Biobank recruited from 2006 to 2010 who were 40 to 70 years of age and free of heart failure at baseline. The mean follow-up time was 12.61 years. The outdoor light exposure time was self-reported at baseline. A restricted cubic spline was performed to examine the potential nonlinear relationship between outdoor light exposure and the incidence of heart failure. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% CIs. During a mean follow-up of 12.61 years, 13 789 participants were first diagnosed with heart failure. There was a nonlinear (J-shaped) trend between outdoor light time and heart failure risk. Cox proportional hazard regression models showed that, compared with participants who received an average of 1.0 to 2.5 hours of outdoor light per day, those with <1.0 hours or >2.5 hours had a higher risk of heart failure after the model was adjusted for age and sex (<1.0 hours: HR, 1.27 [95% CI, 1.18-1.36]; >2.5 hours: HR, 1.11 [95% CI, 1.07-1.15]). These associations were still significant in the fully adjusted models (<1.0 hours: HR, 1.10 [95% CI, 1.03-1.18]; >2.5 hours: HR, 1.07 [95% CI, 1.03-1.11]). We found a J-shaped association between outdoor light exposure time and the risk of incident heart failure, suggesting that moderate exposure to outdoor light may be a prevention strategy for heart failure.

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

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

THE ROLE OF OUTDOOR LIGHT EXPOSURE ON SLEEP QUALITY IN OLDER INDIVIDUALS WITH FRAILTY OF DIFFERENT LIVING TYPES

Abstract The study investigates the relationship between outdoor light exposure and sleep quality in older individuals with frailty in institutions and the community, where sleep disorders are common, and outdoor light exposure is inadequate.The study includes older individuals with frailty in community and institutions in Taiwan. Participants must be aged 65 or above and have a Clinical Frailty Scale score between 4 to 8. We collect sleep quality and outdoor light exposure data using questionnaires and actigraphy.The study includes 77 older individuals: 29 from day-care centers, 22 from conventional long-term care institutions, and 26 from unit care institutions. The average outdoor light exposure is 15 minutes per day, with an average Pittsburgh Sleep Quality Index (PSQI) score of 8, 74% sleep efficiency, and 125.8 minutes of wake after sleep onset. After controlling for multiple variables. Outdoor light exposure shows no relationship with PSQI, sleep efficiency, and wake after sleep onset.The average PSQI score is &amp;gt; 5, indicating poor subjective sleep quality. Additionally, Wake After Sleep Onset &amp;gt; 60 minutes, and sleep efficiency &amp;lt; 75%, suggesting poor objective sleep quality. The average outdoor light exposure time &amp;lt; 20 minutes, indicating a lack of outdoor light exposure. However, our study does not observe the effects of light exposure, possibly because the average daily light exposure is below the 30-minutes threshold. Older individuals with frailty experience poor sleep quality. It is possible that a longer duration of outdoor light exposure may be needed to observe its impact on sleep quality.

Timing of outdoor light exposure is associated with sleep-wake consolidation in community-dwelling older men

IntroductionA consolidated sleep-wake pattern is essential for maintaining healthy cognition in older individuals, but many suffer from sleep fragmentation that exacerbates age-related cognitive decline and worsens overall mental and physical health. Timed light exposure (light therapy) has been explored as a countermeasure, but mixed results have been obtained. To determine whether the timing of light exposure is important for sleep-wake consolidation, we analyzed the natural light diets of a cohort of community-dwelling older men.MethodsThe degree of sleep-wake fragmentation and light exposure patterns were obtained over a week using wrist actigraphy. Correlations between fragmentation, light patterns, and various physical and mental health measures were examined (n = 877).ResultsOur findings revealed that higher sleep-wake fragmentation correlated with poorer physical and mental health and reduced cognition. Moreover, reduced daytime light exposure was associated with increased sleep-wake fragmentation. Interestingly, morning and evening light exposure (&amp;gt;1,000 lux) were not useful in distinguishing between low and high sleep-wake fragmentation scores, while increased afternoon light exposure showed much better discrimination. Specifically, optimal discrimination between low and high fragmentation occurred 6.7 h after habitual sleep offset. This suggests that afternoon light therapy might be more efficient in consolidating sleep and wake in older adults, particularly in those with low-amplitude circadian rhythms.DiscussionThis study highlights the significance of properly-timed light exposure in promoting consolidated sleep and cognitive health among older individuals. Tailored light-based strategies may have the potential to enhance physical, mental, and cognitive well-being in the aging population.

Chronotype and lipid metabolism in Arctic Sojourn Workers

ABSTRACT This study relates answers to the Munich Chronotype Questionnaire (MCTQ) and Pittsburgh Sleep Quality Index (PSQI) from Arctic Sojourn Workers (ASW) of Yamburg Settlement, 68° Latitude North, 75° Longitude East (n = 180; mean age ± SD; range: 49.2 ± 7.8; 25–66 y; 45% women) to Arctic Sojourn Work Experience (ASWE), age and health status. Chronotype, Mid Sleep on Free Days sleep corrected (MSFsc) and sleep characteristics of ASW were compared to those of age-matched Tyumen Residents (TR, n = 270; mean age ± SD; range: 48.4 ± 8.4; 25–69 y; 48% women), 57° Latitude North, 65° Longitude East. ASW have earlier MSFsc than TR (70 min in men, p < 0.0001, and 45 min in women, p < 0.0001). Unlike TR, their MSFsc was not associated with age (r = 0.037; p = 0.627) and was linked to a larger Social Jet Lag (+21 min in men; p = 0.003, and +18 min in women; p = 0.003). These differences were not due to outdoor light exposure (OLE): OLE on work (OLEw) or free (OLEf) days was not significantly different between ASW and TR in men and was significantly less in ASW than in TR women (OLEw: −31 min; p < 0.001; OLEf: −24 min; p = 0.036). ASWE, but not age, was associated with compromised lipid metabolism in men. After accounting for multiple testing, when corrected for age and sex, higher triglycerides to high-density lipoprotein ratio, TG/HDL correlated with ASWE (r = 0.271, p < 0.05). In men, greater SJL was associated with lower HDL (r = -0.204; p = 0.043). Worse proxies of metabolic health were related to unfavorable components of the Pittsburgh Sleep Quality Index in ASW. Higher OLE on free days was associated with lower systolic (b = -0.210; p < 0.05) and diastolic (b = -0.240; p < 0.05) blood pressure.

Invited Session II: Myopia and myopia control: Interactions between Light Exposure and Diurnal Rhythms on the Choroid.

Increasing evidence demonstrates that light exposure and circadian rhythms plays a role in myopia, with high intensity outdoor light being protective. The choroid may be involved in this mechanism. The goals of our studies were to examine the interaction between light exposure and circadian influences on the choroid. In Experiment 1, choroid diurnal rhythms were investigated during monocular light deprivation in adults using spectral domain optical coherence tomography imaging (SD-OCT). The left eye was light deprived for 20 hours. In Experiment 2, the effects of two hours of high intensity outdoor light exposure on retinal and choroid thickness were investigated and compared to indoor illumination and darkness. For Experiment 1, choroid diurnal variation persisted and retinal diurnal variation was eliminated in light deprived eyes. Total retinal and inner segment thicknesses decreased (P < 0.001) and outer segment + RPE thickness increased (P < 0.05) with light deprivation. For Experiment 2, the choroid was significantly thinner during outdoor light exposure compared to indoors and darkness (P < .01), but returned to baseline at follow-up (P > .05). Total retinal thickness was significantly thicker during and after the outdoor compared to indoor and dark conditions (P < .05). These studies demonstrate that the choroid is mediated by both intrinsic circadian mechanisms as well as light exposure. Choroidal thickness rhythms were not impacted by short-term light deprivation. Surprisingly, high intensity sunlight resulted in an unexpected thinning of the choroid. These findings have implications regarding the interaction between light exposure, circadian rhythm, and the choroid on myopia.

Outdoor Light at Night and Children's Body Mass: A Cross-Sectional Analysis in the Fr1da Study

BackgroundEmerging evidence supports an association between light at night (LAN) exposure with obesity or overweight in adults. However, effects of LAN exposure during childhood have yet to be further investigated. ObjectiveIn this study, we aimed to determine whether LAN exposure is associated with body mass in young children. Research design and methodWe used data from the Fr1da cohort study which screened children for early-stage islet autoimmunity in Bavaria, Germany from February 2015 to March 2019. A total of 62,212 children aged <11 years with complete residential information was included in the analysis. Self-reported weight and height were used to calculate age- and sex-specific body mass index (BMI) z-scores. LAN exposure was based on remotely sensed images from Visible Infrared Imaging Radiometer Suite and assigned to the children's residencies. We used generalized additive models to estimate the associations between LAN exposure and BMI adjusting for potential confounders. ResultsWe observed an increase in BMI z-scores of 34.0% (95% confidence interval (CI): 25.4–42.6) per 10 nW/cm2/sr increment in LAN exposure at baseline (2015) and of 32.6% (24.3–41.0) for LAN exposure one year prior to screening, both adjusted for age and sex. Similar associations were observed after adjustment for socioeconomic status and urbanization degree. ConclusionOur findings suggest that outdoor light exposure may be a risk factor for weight gain during childhood.

Effect of Text Messaging Parents of School-Aged Children on Outdoor Time to Control Myopia

Myopia in school-aged children is a public health issue worldwide; consequently, effective interventions to prevent onset and progression are required. To investigate whether SMS text messages to parents increase light exposure and time outdoors in school-aged children and provide effective myopia control. This randomized clinical trial was conducted in China from May 2017 to May 2018, with participants observed for 3 years. Of 528 965 primary school-aged children from Anyang, 3113 were randomly selected. Of these, 268 grade 2 schoolchildren were selected and randomly assigned to SMS and control groups. Data were analyzed from June to December 2021. Parents of children in the SMS group were sent text messages twice daily for 1 year to take their children outdoors. All children wore portable light meters to record light exposure on 3 randomly selected days (2 weekdays and 1 weekend day) before and after the intervention. The co-primary outcomes were change in axial length (axial elongation) and change in spherical equivalent refraction (myopic shift) from baseline as measured at the end of the intervention and 3 years later. A secondary outcome was myopia prevalence. Of 268 grade 2 schoolchildren, 121 (45.1%) were girls, and the mean (SD) age was 8.4 (0.3) years. Compared with the control group, the SMS intervention group demonstrated greater light exposure and higher time outdoors during weekends, and the intervention had significant effect on axial elongation (coefficient, 0.09; 95% CI, 0.02-0.17; P = .01). Axial elongation was lower in the SMS group than in the control group during the intervention (0.27 mm [95% CI, 0.24-0.30] vs 0.31 mm [95% CI, 0.29-0.34]; P = .03) and at year 2 (0.39 mm [95% CI, 0.35-0.42] vs 0.46 mm [95% CI, 0.42-0.50]; P = .009) and year 3 (0.30 mm [95% CI, 0.27-0.33] vs 0.35 mm [95% CI, 0.33-0.37]; P = .005) after the intervention. Myopic shift was lower in the SMS group than in the control group at year 2 (-0.69 diopters [D] [95% CI, -0.78 to -0.60] vs -0.82 D [95% CI, -0.91 to -0.73]; P = .04) and year 3 (-0.47 D [95% CI, -0.54 to -0.39] vs -0.60 D [95% CI, -0.67 to -0.53]; P = .01) after the intervention, as was myopia prevalence (year 2: 38.3% [51 of 133] vs 51.1% [68 of 133]; year 3: 46.6% [62 of 133] vs 65.4% [87 of 133]). In this randomized clinical trial, SMS text messages to parents resulted in lower axial elongation and myopia progression in schoolchildren over 3 years, possibly through increased outdoor time and light exposure, showing promise for reducing myopia prevalence. Chinese Clinical Trial Registry Identifier: ChiCTR-IOC-17010525.

0216 Environmental bright light exposure is associated with sleep timing: the Multi-Ethnic Study of Atherosclerosis

Abstract Introduction Light influences sleep via the circadian system, but few studies have examined objective light exposure and sleep outcomes in the general population. We investigated the relationship between daily average time above 1,000 lux white light (TALT1000), a proxy for outdoor light exposure, and actigraphy measures of sleep timing and regularity in the Multi-Ethnic Study of Atherosclerosis (MESA). Methods Light and actigraphy data collected over 5+ days (wrist-worn Actiwatch Spectrum) were analyzed. Relationships between TALT1000 and dichotomized sleep timing measures (sleep midpoint regularity, defined as &amp;lt;30 minutes variability in sleep timing; late sleep onset, defined as 12AM or later) were evaluated with logistic regression models, adjusted for age, self-reported race/ethnicity, sex, federal poverty level, partner status, employment, smoking, BMI, depression score, sleep duration, day length by month and site, chronotype, number of days measured, ActiWatch off-wrist time, and average physical activity during active period. Stratified analyses for employment status and sleep duration were also conducted. Covariates associated with quartiles of TALT1000 were evaluated with ordinal logistic regression. Results 2,135 MESA participants with valid actigraphy data were included (mean age=68.6 years, 53.8% female, mean TALT1000=61 minutes, mean sleep midpoint variability=70.6 minutes). There was a dose-response relationship between quartiles of TALT1000 and sleep timing regularity, with participants in the highest quartile of TALT1000 exposure (equivalent to 90+ minutes daily bright light exposure) having 87.7% increased odds of sleep timing regularity (adjOR=1.88, CI=1.35-2.62); the highest quartile of TALT1000 was also associated with a 41% decreased odds of sleep onset timing ≥12AM (adjOR=0.59, CI=0.43-0.81). Age, race/ethnicity, partner status (single), and day length were negatively associated, while BMI, sex (male), earlier chronotype, and physical activity were positively associated with quartiles of TALT1000 (p&amp;lt;0.05). Conclusion Greater average bright light exposure is associated with greater sleep timing regularity and earlier sleep onset in a large sample of U.S. adults. Future analyses will investigate timing of light exposure and associated multi-omic signatures. Support (If Any) NIH-NHLBI T32HL007901, R35HL135818, R01HL098433, R24HL114473, 75N92019R002.

Time spent outdoors as an intervention for myopia prevention and control in children: an overview of systematic reviews.

PurposeOutdoor light exposure is considered a safe and effective strategy to reduce myopia development and aligns with existing public health initiatives to promote healthier lifestyles in children. However, it is unclear whether this strategy reduces myopia progression in eyes that are already myopic. This study aims to conduct an overview of systematic reviews (SRs) reporting time spent outdoors as a strategy to prevent myopia or slow its progression in children.MethodsWe searched the Cochrane Library, EMBASE, MEDLINE and CINAHL from inception to 1 November 2020 to identify SRs that evaluated the association between outdoor light exposure and myopia development or progression in children. Outcomes included incident myopia, prevalent myopia and change in spherical equivalent refraction (SER) and axial length (AL) to evaluate annual rates of myopia progression. The methodological quality and risk of bias of included SRs were assessed using the AMSTAR‐2 and ROBIS tools, respectively.ResultsSeven SRs were identified, which included data from 47 primary studies with 63,920 participants. Pooled estimates (risk or odds ratios) consistently demonstrated that time outdoors was associated with a reduction in prevalence and incidence of myopia. In terms of slowing progression in eyes that were already myopic, the reported annual reductions in SER and AL from baseline were small (0.13–0.17 D) and regarded as clinically insignificant. Methodological quality assessment using AMSTAR‐2 found that all reviews had one or more critical flaws and the ROBIS tool identified a low risk of bias in only two of the included SRs.ConclusionThis overview found that increased exposure to outdoor light reduces myopia development. However, based on annual change in SER and AL, there is insufficient evidence for a clinically significant effect on myopia progression. The poor methodological quality and inconsistent reporting of the included systematic reviews reduce confidence in the estimates of effect.

Melatonin, circadian rhythms and glaucoma: current perspective.

Melatonin, circadian rhythms and glaucoma: current perspective.

Behavioral Measures in Myopic and Non-myopic High Schoolers During the COVID Pandemic

Purpose: The purpose of this study is to understand how the visual activity of highschool students in Houston changed due to quarantine and online learning during the COVID-19 pandemic, and whether these behaviors were different between myopes and non-myopes.&#x0D; Methods: Thirty-one participants (16.3±0.8 years, 8 females), including 12 myopes and 8 non-myopes, wore a Clouclip and Actiwatch for a week. The Clouclip records working distance and the Actiwatch measures light exposure, physical activity, and sleep duration. A questionnaire was also completed regarding demographics, ocular history, and visual behaviors.&#x0D; Results: Data showed that myopic participants engaged in near work (working distances of 10 to &lt;60 cm) for 8.4±2.6 hours on a week day and 6.5±2.1 hours on a weekend day. Non-myopic participants engaged in near work for 6.1±2.7 hours on a week day and 4.5±1.9 hours on a weekend day. While weekend near work was significantly different between refractive error groups (P&lt;.05), weekday near work (P=.08) was not. There were no differences between refractive error groups for daily light exposure (P = .89), time outdoors (P = .44), or sleep duration (P = .80).&#x0D; Conclusions: There was no significant change in sleep duration and physical activity regardless of refractive error over the pandemic, while results revealed a significant decrease in outdoor light exposure and the increase in near and intermediate work, especially with electronic devices such as the computer.

Environmental Triggers in Migraine patients in Riyadh: A Cross-Sectional Study

Background: A migraine is a disabling condition that is characterized by persistent headaches which vary in severity. Migraines are extremely common and represent a major public health concern due to their effect on the quality of life and job performance, which can also lead to a significant financial burden on global economies [1]. Methodology: In this cross-sectional study, a self-administered questionnaire was distributed among migraineurs attending primary healthcare centers and hospitals in Riyadh, Saudi Arabia. The survey included questions about sociodemographic data, number of attacks, and environmental factors triggering migraines, in order to assess their prevalence. Results: A total of 415 participants were recruited. The most common age group was 31– 50 years old (46.5%), with females dominating the males (84.8% vs 15.2%). The prevalence of migraines that affected activities of daily living (ADL) was 80% (CI=75.7% - 84.3%). The most common environmental factors that triggered migraines were noise (87.7%), followed by outdoor light exposure (81.4%), and indoor lighting, such as fluorescent light, and computer systems (79%). In univariate analyses, migraines that interfered with ADL were more common in patients with a bachelor’s degree (p=0.019) and those who were taking migraine medication (p=0.003). Conclusion: Migraines are highly prevalent in our region, most specifically among women. Noise, outdoor light exposure, indoor lighting, fluorescent lights, and computer systems usage were the most triggering environmental factors of migraines. These factors dissuade patients from doing their daily activities. Key words: Migraine, environmental factors, patients, primary healthcare center.

Objective Behavioral Measures in Children before, during, and after the COVID-19 Lockdown in Israel.

Studies using questionnaires report that COVID-19 restrictions resulted in children spending significantly less time outdoors. This study used objective measures to assess the impact of pandemic-related restrictions on children’s behavior. A total of 19 healthy 8–12-year-old boys were observed before and during social restriction periods. Of these, 11 boys were reassessed after restrictions were lifted. For each session, Actiwatches were dispensed for measures of time outdoors, activity, and sleep. Changes overall and by school status were assessed using signed-rank test and Wilcoxon rank sum tests. During restrictions, children spent significantly less time outdoors (p = 0.001), were less active (p = 0.001), and spent less time engaged in moderate-to-vigorous physical activity (p = 0.004). Sleep duration was not significantly different between sessions (p > 0.99), but bedtime and wake time shifted to a later time during restrictions (p < 0.05 for both). Time outdoors and activity returned close to pre-pandemic levels after restrictions were lifted (p > 0.05 for both). Children’s behaviors significantly changed during the COVID-19 pandemic. The reduction in outdoor light exposure is of importance due to the role of light in the etiology of myopia and vitamin D production. The reduction in physical activity may have negative health effects in terms of obesity and depression, although further research is required to ascertain the long-term effects.

Later sleep timing predicts accelerated summer weight gain among elementary school children: a prospective observational study

Objectives and backgroundSocial demands of the school-year and summer environment may affect children’s sleep patterns and circadian rhythms during these periods. The current study examined differences in children’s sleep and circadian-related behaviors during the school-year and summer and explored the association between sleep and circadian parameters and change in body mass index (BMI) during these time periods.MethodsThis was a prospective observational study with 119 children ages 5 to 8 years with three sequential BMI assessments: early school-year (fall), late school-year (spring), and beginning of the following school-year in Houston, Texas, USA. Sleep midpoint, sleep duration, variability of sleep midpoint, physical activity, and light exposure were estimated using wrist-worn accelerometry during the school-year (fall) and summer. To examine the effect of sleep parameters, physical activity level, and light exposure on change in BMI, growth curve modeling was conducted controlling for age, race, sex, and chronotype.ResultsChildren’s sleep midpoint shifted later by an average of 1.5 h during summer compared to the school-year. After controlling for covariates, later sleep midpoints predicted larger increases in BMI during summer, (γ = .0004, p = .03), but not during the school-year. Sleep duration, sleep midpoint variability, physical activity levels, and sedentary behavior were not associated with change in BMI during the school-year or summer. Females tended to increase their BMI at a faster rate during summer compared to males, γ = .06, p = .049. Greater amounts of outdoor light exposure (γ = −.01, p = .02) predicted smaller increases in school-year BMI.ConclusionsObesity prevention interventions may need to target different behaviors depending on whether children are in or out of school. Promotion of outdoor time during the school-year and earlier sleep times during the summer may be effective obesity prevention strategies during these respective times.

660 Chronotype Associations with Insomnia, Depressive Symptoms, and Changes in Sleep and Health Behaviors during the COVID-19 Pandemic

IntroductionEvening chronotype (i.e., night owl preference) is associated with worse insomnia and depressive symptoms, and poorer health behaviors. The aim of this study was to examine the association between chronotype and these symptoms and health behaviors during COVID-19 pandemic quarantine.MethodsAn online survey, distributed internationally via social media from 5/21/2020–7/1/2020, asked adults to report sociodemographic/economic information, changes in sleep (midpoint, total sleep time, sleep efficiency, time-in-bed), and health behaviors (i.e., physical activity, sedentary screen time, and outdoor light exposure patterns) from prior to during the pandemic, chronotype preference (definitely morning [DM], rather more morning [RM], rather more evening [RE], or definitely evening [DE]), and complete the Insomnia Severity Index (ISI) and the 10-item Center for Epidemiologic Studies Depression scale (CES-D-10). Multinomial logistic regression and ANCOVA models, adjusting for age and sex, examined associations of chronotype with COVID-19 pandemic related impacts on sleep, depressive symptoms, and health behaviors.ResultsA subsample of 579 participants (M age: 39y, range: 18–80; 73.6% female), currently under quarantine and neither pregnant nor performing shift work, represented each chronotype evenly (~25%). Participants delayed their sleep midpoint by 72.0min (SD=111.5) during the pandemic. DE chronotypes had a greater delay than morning types (M±SD DE: 91.0±9.0 vs. RM: 55.9±9.2 & DM: 66.1±9.3; p=0.046) with no significant change in other sleep patterns relative to other chronotypes. However, DE and RE chronotypes had greater odds of reporting that their new sleep/wake schedule was still not consistent with their “body clock” preference relative to morning types (Χ2[15]=54.8, p<0.001), reported greater ISI (F[3,503]=5.3, p=.001) and CES-D-10 scores (F[3,492]=7.9, p<.001), and had greater odds for increased or consistently moderate-to-high sedentary screen time (Χ2[12]=22.7, p=0.03) and decreased physical activity (Χ2[12]=22.5, p=0.03) than DM chronotype. There was no significant difference in change in outdoor light exposure by chronotype (Χ2[12]=12.1, p=0.43).ConclusionIn an international online sample of adults under COVID-19 pandemic quarantine, evening chronotypes, despite taking the opportunity to delay sleep to match biological clock preference, reported their sleep/wake schedules were still inconsistent with personal preference, and reported greater insomnia and depressive symptoms, and odds of engaging in poorer health behaviors than morning chronotypes.Support (if any):

Myopia, Melatonin and Conjunctival Ultraviolet Autofluorescence: A Comparative Cross-sectional Study in Indian Myopes

ABSTRACT Purpose: To explore the role of outdoor light exposure by estimating ocular sun exposure measured by Conjunctival Ultraviolet Autofluorescence (CUVAF) imaging and serum melatonin levels in myopes and non-myopes. Materials & Methods: Age and sex matched emmetropes and myopes (60 each) aged 10–25 years participated. Those with a history of ocular surgery or any ocular or systemic co-morbidity were excluded. Socio-demographic parameters, sun exposure questionnaires, indoor and outdoor activity profile, morning serum melatonin levels, sleep pattern, degree of myopia, ocular biometry and area of CUVAF on ultraviolet photography were noted and analyzed. Results: Mean age of myopes (18 ± 4.5 years) and emmetropes (18.5 ± 4 years) was similar (P = .523). Serum melatonin levels were significantly higher (P = .001) among myopes (89.45 pg/ml) as compared to emmetropes (52.83 pg/ml). Lifetime sun exposure was significantly lower in myopes than emmetropes (P = .0003). Area of CUVAF was inversely related to degree of myopia (P < .0001). Day time sleepiness was greater in myopes (51.7%) than emmetropes (15%) (P < .0001). There was a positive correlation between serum melatonin levels and axial length among myopes (correlation coefficient = 0.27; P = .03). Age and gender had no association with serum melatonin levels. Conclusion: This study demonstrates an inverse relationship between serum melatonin levels and degree of CUVAF in myopes. A novel link between serum melatonin, axial length and outdoor sun exposure is highlighted in the current study.

Dose-Response Relationship of Outdoor Exposure and Myopia Indicators: A Systematic Review and Meta-Analysis of Various Research Methods.

Myopia in children has dramatically increased worldwide. A systematic review and meta-analysis were conducted to evaluate the effects of outdoor light exposure on myopia. According to research data from 13 studies of 15,081 children aged 4–14 at baseline, outdoor light exposure significantly reduced myopia incidence/prevalence (odds ratio [OR] = 0.85, 95% confidence interval [CI]: 0.80–0.91, p < 0.00001; I2 = 90%), spherical equivalent refractive error (SER) by 0.15 D/year (0.09–0.27, p < 0.0001), and axial elongation by 0.08 mm/year (−0.14 to −0.02, p = 0.02). The benefits of outdoor light exposure intervention, according to pooled overall results, included decreases in three myopia indicators: 50% in myopia incidence, 32.9% in SER, and 24.9% in axial elongation for individuals in Asia. Daily outdoor light exposure of more than 120 min was the most effective intervention, and weekly intervention time exhibited a dose–response relationship with all three indicators. Subgroup comparisons revealed that interventional studies report greater benefits from outdoor light exposure compared with cohort and cross-sectional studies, and individuals with myopia in intervention studies experienced slightly greater benefits than individuals without, in terms of SER and axial elongation. Therefore, this study suggests 120 min/day of outdoor light exposure at school.