Background: In the U.S., poor sleep is linked to childhood obesity. During the Coronavirus Disease 2019 (COVID-19) pandemic, home confinement and school closures intensified obesogenic sleep behaviors, potentially contributing to increased childhood obesity and overweight prevalence, particularly among marginalized children.

Objective: To examine the association between sleep behaviors and weight in children (preschool) and young adolescents (school-aged) during the COVID-19 pandemic, exploring socioeconomic status and race/ethnicity as potential mediators of this association.

Methods: We examined data from a longitudinal cohort study of U.S. children aged 4 to 15 years. Participating families were drawn from a COVID-19 family study, including data collected early and mid-pandemic, and included pre-pandemic data for those re-enrolled from two cluster randomized-controlled trials. Nighttime sleep behaviors were assessed using actigraphy for sleep onset trajectories and surveys for sleep disturbance and bedtime resistance. Regression models examined the association between these sleep behaviors and mid-pandemic BMI-for-age z-scores.

Results: The investigation of objectively measured sleep onset in both preschool and school-aged cohorts revealed trajectory-defined shifts in sleep onset yet did not detect a statistically significant association with mid-pandemic BMIz after accounting for confounders. For school-aged children, sleep disturbance was a modest predictor of mid-pandemic BMIz after adjusting for sleep duration and other covariates, where a one-unit standard deviation change in sleep disturbance score was positively associated with mid-pandemic BMIz; however, this association attenuated after adjusting for baseline weight. Evidence also suggested that socioeconomic status was an effect modifier. For preschoolers, a statistically significant independent association between bedtime resistance and mid-pandemic BMIz was not observed, nor was there evidence that race/ethnicity moderated this relationship in this sample.

Conclusions: Obesity prevention efforts should address multiple behaviors, including sufficient and high-quality sleep, to promote healthy weight rather than targeting single aspects of poor sleep. Sleep hygiene interventions are needed for vulnerable children affected most by public health emergencies. Future research should examine pediatric cohorts using comprehensive, long-term assessments of sleep exposures.