0249 Early Differences in Social Jetlag Across Racial and Ethnic Groups in U.S. Children

Abstract Introduction Growing evidence highlights the importance of maintaining regular sleep timing, beyond sufficient sleep duration, for numerous sleep and health outcomes. Social jetlag (SJL), a measure of sleep irregularity and a proxy for circadian misalignment, has been observed in children as young as 2 years, increasing across development. Although racial/ethnic differences in children’s sleep duration and quality are well established, no studies to date have examined differences in SJL. Methods Data were analyzed across 5,348 children ages 2-11 years (52.7% Non-Hispanic White, 9.0% Asian, 20.6% Hispanic/Latino, 17.6% Black/African-American, 49.7% female) collected from 2018-2022 as part of the NIH Environmental Influence on Child Health Outcome (ECHO) study. Sleep timing and racial/ethnic identity were collected via parent-report through completion of the ECHO Child Sleep Health Questionnaire and the ECHO Demographic of the Biological Family survey. SJL was calculated as the difference between weekday and weekend midsleep times. Weekend midsleep times were adjusted to account for sleep extension due to accumulated weekday sleep loss. Results Between subjects ANOVA revealed significant main effects of age and race/ethnicity, and a significant age x race/ethnicity interaction (all p < 0.001). SJL was significantly greater overall for Hispanic/Latino and Black/African-American children relative to Non-Hispanic White White and Asian children and increased in magnitude with age across all groups. Small racial/ethnic differences in SJL were observed in children ages 2-4, growing significantly with advancing age. Substantial racial/ethnic differences in sleep timing were already present at age 2, with weekday and weekend midsleep times for Non-Hispanic White children occurring 40 and 55 min earlier than Black/African-American children and 58 and 73 min earlier than Hispanic/Latino children. Conclusion Racial/ethnic differences in parent-reported SJL emerged as early as age 2, increasing with the transition to formal schooling and the need to adhere to fixed start times. Given the expanding recognition of sleep regularity as a key factor in healthy development, these findings point to a potential early contributor to group differences in sleep health and underscore the need to identify factors driving these differences. Such work is critical for informing interventions and policies that support healthy sleep for all children. Support (if any)