Short sleep duration and body mass index: a prospective longitudinal study in preadolescence.

Short sleep duration is associated with incidence of overweight and obesity in preadolescent children. The authors performed regression analyses on data from the Quebec Longitudinal Study of Kindergarten Children (1986-1987), a prospective cohort study comprising 1,916 preadolescent children in Canada. The aim was to assess associations between time spent in bed and body mass index reported by mothers after adjusting for numerous confounding factors, such as pubertal status. Time-in-bed and body mass index trajectories were computed using a semiparametric model mixture. Time-in-bed trajectories were classified as short (15% of the preadolescents), 10.5-hour (68%), and 11-hour (17%) sleep-duration trajectories, decreasing over time. Body mass index trajectories were classified as normal weight (68% of the preadolescents), overweight (27%), and obese (5%). The short sleep trajectory was associated with an increased odds ratio of being in the overweight body mass index trajectory (odds ratio (OR)=1.55, 95% confidence interval (CI): 1.39, 1.71) or in the obese body mass index trajectory (OR=3.26, 95% CI: 3.20, 3.29) compared with the 11-hour trajectory. One hour less of sleep per night at 10 years of age was associated with an increased odds ratio of being overweight (OR=1.51, 95% CI: 1.28, 1.76) or obese (OR=2.07; 95% CI: 1.51, 2.84) at 13 years of age.