Looking beyond sleep duration in understanding obesity risk in adolescents: the role of circadian timing and misalignment on adolescent dietary outcomes, physical activity, and body mass index.

Study objectives: This study evaluated the differences in obesity-related outcomes across multiple adolescent sleep health domains, including circadian misalignment (CM), circadian timing, and sleep duration.

Methods: 53 adolescents (aged 14-18; body mass index [BMI] percentile < 95%; 53.7% female) completed a cross-sectional study that included baseline assessment of height; weight; demographics; and 10 days assessment of sleep, physical activity, and dietary outcomes. Sleep duration, sleep timing, and physical activity data were collected from all participants using wrist-worn and waist-worn actigraphs. Dietary intake was measured using the Automated Self-Administered 24 Hours dietary recalls on 3 randomized days. Circadian timing was measured using dim-light melatonin onset (DLMO), and CM was calculated as the distance of time between DLMO and the average sleep onset time. Participants were categorized into groups (early vs late circadian timing, aligned vs misaligned circadian timing, and adequate sleep vs short sleep), and differences in dietary outcomes, physical activity, and BMI were analyzed using t-tests.

Results: Adolescents with later DLMO (M = 21:30 ± 1:11) had 0.63 higher BMI and 0.47% less averaged daily percent fat consumption than adolescents with early DLMO. Adolescents with CM (M = 1:42 ± 1:06) consumed 451.77 more averaged daily kcal consumption compared with those with circadian alignment. No statistically significant differences were found in any obesity-related outcome between sleep duration groups.

Conclusions: Our cross-sectional findings indicate that focusing on sleep timing and circadian alignment, beyond sleep duration, may promote better health outcomes for healthy adolescents. The findings of this study could enhance sleep education and inform clinical models for prevention efforts for pediatric obesity.