0652 Delayed Sleep Time In African Americans And Depression In A Community-Based Population

Abstract Introduction Experimental studies have suggested a shorter circadian period in African Americans when compared to Non-Hispanic Whites, and suggest racial differences in circadian phase shifting in such experiments. Observational studies that indicate that delayed sleep phase is associated with depression. Whether delayed sleep time is associated with depression in a community-based population and the influence of race on such an association are largely unknown. We tested the hypothesis that in a community-based population, the prevalence of delayed sleep time is greater in African Americans when compared to Whites. We also tested the hypothesis that depression is associated with delayed sleep time in a community based population. Methods We analyzed data from the Sleep Heart Health Study, which is a large community-based sample (n=6,441). Self-reported time to fall asleep on weekdays and weekends was available for analysis. Covariates included age, sex, race, body mass index, smoking, apnea-hypopnea index, alcohol, antidepressant medications, and caffeine. Depression was defined based on participant’s response to the question, “In the past 4 weeks have you felt downhearted and blue?” and/or anti-depressants in their medication list. Delayed sleep time was defined as a usual time to fall asleep after midnight. Results After adjusting for covariates, weekday self-reported time to fall asleep was 26 ± 12 minutes later in African Americans when compared to Non-Hispanic whites (P=0.03). Similarly, weekend time to fall asleep was 27 ± 12 minutes later in African Americans when compared to Non-Hispanic whites (P=0.025). The proportion of individuals with delayed sleep time was greater in African Americans (33.3%) when compared to Non-Hispanic whites (18.7%; P