title: Reduced risk for overweight and obesity in 5- and 6-y-old children by duration of sleep--a cross-sectional study.
abstract: OBJECTIVE
  To assess the relationship between sleep duration and adiposity in 5- and 6-y-old Bavarian children.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  A total of 6862 German children aged 5-6 y participating in the obligatory health examination in Bavaria, southern Germany.
  
  
  METHODS
  Routine data were collected on the height and weight of children at the time of school entry in six public health offices in 1999 and in another two in 2000. Body fat mass was estimated by BIA performed in three of those offices. An extensive questionnaire was given to all children's parents in order to assess risk factors for overweight and obesity. The main outcome measures were overweight, defined by a body mass index (BMI) above the 90th centile and obesity, defined by a BMI above the 97th centile for the German children in Bavaria. Excessive body fat was defined as fat mass above the 90th centile for all German children seen in this survey. The main exposure was usual sleeping hours on week days.
  
  
  RESULTS
  The prevalence of obesity decreased by duration of sleep: < or =10 h, 5.4% (95% CI 4.1-7.0), 10.5-11.0 h, 2.8% (95% CI 2.3-3.3), and > or =11.5 h, 2.1% (95% CI 1.5-2.9). Similar relations were found with the prevalence of overweight and excessive body fat. These effects could not be explained by confounding due to a wide range of constitutional, sociodemographic and lifestyle factors. The adjusted odds ratio for obesity were: for sleeping 10.5-11.0 h, 0.52 (95% CI 0.34-0.78) and 0.46 (95% CI 0.28-0.75) for sleeping 11.5 h.
  
  
  CONCLUSIONS
  The effect of sleep duration on obesity in children reflects a higher body fat composition and appears to be independent of other risk factors for childhood obesity.
authors.affiliation: Institute for Social Paediatrics and Adolescent Medicine, Ludwig-Maximilians University of Munich, Munich, Germany.
authors.forename: R
authors.initials: R
authors.lastname: von Kries
authors.forename: A M
authors.initials: AM
authors.lastname: Toschke
authors.forename: H
authors.initials: H
authors.lastname: Wurmser
authors.forename: T
authors.initials: T
authors.lastname: Sauerwald
authors.forename: B
authors.initials: B
authors.lastname: Koletzko
mesh_terms: D000273:Adipose Tissue; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005858:Germany / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D009765:Obesity / Q000453:epidemiology*; D016017:Odds Ratio; D012307:Risk Factors; D012890:Sleep; D011795:Surveys and Questionnaires; D013997:Time Factors