Longitudinal associations between sleep and weight status in infants and toddlers

BackgroundThe limited research assessing relationships between sleep duration and weight status in infants and toddlers relies primarily on parent-reported sleep and cross-sectional studies. ObjectivesExamine whether average sleep duration and changes in sleep duration among 6-24-month-old children were associated with weight-for-length z-scores, and whether these associations varied by race/ethnicity, socioeconomic status and sex. MethodsData were collected when children were approximately 6, 12, 18 and 24 months old (N = 116). Sleep duration was measured using actigraphy. Weight-for-length z-scores were calculated using children's height and weight. Physical activity was assessed using accelerometry. Diet was assessed using a feeding frequency questionnaire. Demographic characteristics included sex, race/ethnicity and socioeconomic status. Separate associations of between- and within-person changes in sleep duration were estimated with weight-for-length z-score treated as the outcome variable in linear mixed model analyses. Additional models were assessed that included interactions between sleep and demographic characteristics. ResultsAt time points where children slept longer at night compared to their own average, their weight-for-length z-score was lower. This relationship was attenuated by physical activity levels. ConclusionsIncreasing sleep duration can improve weight status outcomes in very young children who have low physical activity levels.