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