title: Shortened nighttime sleep duration in early life and subsequent childhood obesity.
abstract: OBJECTIVE
  To test associations between daytime and nighttime sleep duration and subsequent obesity in children and adolescents.
  
  
  METHODS
  Prospective cohort.
  
  
  METHODS
  Panel Survey of Income Dynamics Child Development Supplements (1997 and 2002) from US children.
  
  
  METHODS
  Subjects aged 0 to 13 years (n = 1930) at baseline (1997).
  
  
  METHODS
  Binary indicators of short daytime and nighttime sleep duration (<25th percentile of age-normalized sleep scores) at baseline.
  
  
  METHODS
  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.
authors.affiliation: Department of Health Services, School of Public Health, University of Washington, Seattle, WA 98198-7230, USA. jfbell@u.washington.edu
authors.forename: Janice F
authors.initials: JF
authors.lastname: Bell
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Zimmerman
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology; D011446:Prospective Studies; D012307:Risk Factors; D012890:Sleep; D013997:Time Factors