Objective: To test associations between daytime and nighttime sleep duration and subsequent obesity in children and adolescents.
Design: Prospective cohort.
Setting: Panel Survey of Income Dynamics Child Development Supplements (1997 and 2002) from US children.
Participants: Subjects aged 0 to 13 years (n = 1930) at baseline (1997).
Main exposures: Binary indicators of short daytime and nighttime sleep duration (<25th percentile of age-normalized sleep scores) at baseline.
Main outcome measures: Body mass index at follow-up (2002) was converted to age- and sex-specific z scores and trichotomized (normal weight, overweight, obese) using established cut points. Ordered logistic regression was used to model body mass index classification as a function of short daytime and nighttime sleep at baseline and follow-up, and important covariates included socioeconomic status, parents' body mass index, and, for children older than 4 years, body mass index at baseline.
Results: For younger children (aged 0-4 years at baseline), short duration of nighttime sleep at baseline was strongly associated with increased risk of subsequent overweight or obesity (odds ratio = 1.80; 95% confidence interval, 1.16-2.80). For older children (aged 5-13 years), baseline sleep was not associated with subsequent weight status; however, contemporaneous sleep was inversely associated. Daytime sleep had little effect on subsequent obesity in either group.
Conclusions: Shortened sleep duration in early life is a modifiable risk factor with important implications for obesity prevention and treatment. Insufficient nighttime sleep among infants and preschool-aged children may be a lasting risk factor for subsequent obesity. Napping does not appear to be a substitute for nighttime sleep in terms of obesity prevention.