title: Sleep duration and obesity in children: is the association dependent on age and choice of the outcome parameter?
abstract: OBJECTIVE
  To assess the association between sleep duration in children and different markers of body fat by age and weight status.
  
  
  METHODS
  Nation-wide health survey. Measurement of BMI and body fat percentage (KFA) calculated from weight, height, skin fold thickness, age, and sex. Sleep duration and potential confounding variables were assessed in a parent questionnaire.
  
  
  METHODS
  N/A.
  
  
  METHODS
  7767 German resident children from 3 to 10 years of age.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Prolongation of sleep duration from the lowest to the highest percentile accounted for a similar mean decrease founding variables and did not show a systematic age dependency. The greatest effects of sleep duration were seen for the upper tails of the BMI and KFA distributions, which were about four as high as the lower tails.
  
  
  CONCLUSIONS
  The association between sleep duration and weight status is of similar size through ages 3 to 10 years. The sleep-associated changes in BMI are likely to be a consequence of higher body fat and primarily affect children whose BMI or KFA is already elevated. These findings favor hormonal pathways nurturing adipose tissue playing a key role in the underlying physiological mechanisms.
authors.affiliation: Institute for Social Paediatrics and Adolescent Medicine, Ludwig-Maximilians University, Munich, Germany Otmar.Bayer@lrz.uni-muenchen.de
authors.forename: Otmar
authors.initials: O
authors.lastname: Bayer
authors.forename: Angelika Schaffrath
authors.initials: AS
authors.lastname: Rosario
authors.forename: Martin
authors.initials: M
authors.lastname: Wabitsch
authors.forename: Rüdiger
authors.initials: R
authors.lastname: von Kries
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000367:Age Factors; D015992:Body Mass Index; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D015986:Confounding Factors, Epidemiologic; D005260:Female; D005858:Germany / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology; D010290:Parents; D017678:Sex Distribution; D012885:Skinfold Thickness; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000378:metabolism; D011795:Surveys and Questionnaires; D013997:Time Factors