0200 Greater Social Jetlag Is Associated with Higher BMI-z in Early Childhood

Abstract Introduction Misalignment between biological and social timing, as evidenced by the weekend-weekday difference in sleep midpoint, is termed social jetlag (SJL). SJL is associated with higher BMI and obesity in adults, adolescents, and older children; however, to our knowledge, no research to date has addressed SJL and BMI in early childhood. The present study examined the relationship between SJL and BMI-z in young children aged 2.0–8.9 years. We hypothesized that children with greater SJL would have higher BMI-z, before and after adjusting for potential covariates. Methods Data were collected from 158 children aged 2.0–8.9 years (M = 5.6 ± 1.98y, 46.2% females) from the RESONANCE cohort of the NIH Environmental Influences on Child Health Outcomes (ECHO) study between 2018–2021. Caregivers completed the ECHO Child Sleep Health Questionnaire and trained staff measured children’s height and weight. Age- and sex-adjusted BMI-z was computed (CDC). SJL was calculated as the weekend-weekday difference in nocturnal sleep midpoint. Primary linear regression models adjusted for child age, sex, race, ethnicity, and maternal education; secondary models further adjusted for average sleep duration, weekday-weekend sleep duration difference, and napping frequency. Results On average, weekend midpoints were 41 minutes later relative to weekdays (t(157) = 12.5, p 0.001). A positive association between SJL and BMI-z was observed in unadjusted and adjusted linear regression models. After controlling for all covariates, SJL remained significantly associated with BMI-z (R2 = 0.54, F(14, 143) = 12.18, p 0.001). For every 1hr of SJL, BMI-z increases 0.389 units (b = 0.00647, p = 0.016). In children already overweight or obese, 1hr increase in SJL is associated with a 0.893 unit increase in BMI-z (b = 0.0149, p 0.001). Conclusion Greater SJL was related to higher BMI-z in young children, consistent with findings in older children, adolescents, and adults. Thus, SJL may represent an obesity risk factor in early childhood. Targeted interventions to promote sleep regularity, especially in already overweight/obese children, may be beneficial. Future research should examine cumulative impacts of SJL across development and employ objective measures of body weight, including adiposity and waist circumference. Support (if any) UH3-0D023313