title: Lack of sleep could increase obesity in children and too much television could be partly to blame.
abstract: OBJECTIVE
  To examine the bidirectional relationship between short sleep duration and body mass index (BMI). A secondary aim was to investigate whether reduced physical activity and increased screen time (television and computer use) mediated these associations.
  
  
  METHODS
  This study utilised data from the Longitudinal Study of Australian Children, which is an observational cohort study of Australian children. The sample included 2984 (52.4% boys) children followed from 4 to 5 years of age until 8 to 9 years of age. Sleep duration, screen time and covariates were reported by parents, with BMI measured objectively. Cross-lagged modelling investigated the bidirectional association between sleep duration and BMI; lagged panel mediation modelling examined physical activity and screen time as potential mediators.
  
  
  RESULTS
  Short sleep duration at 4 to 5 years of age was significantly associated with higher BMI at 8 to 9 years of age (β= -.07, p = .044). The relationship between short sleep duration at 4 to 5 years of age and higher BMI at 8 to 9 years of age was partially mediated by increased television viewing at 6 to 7 years of age (β = -.01, 95% confidence interval [-.02, -.002]).
  
  
  CONCLUSIONS
  Short sleep duration could be a risk factor for obesity in children. Increased television viewing may be one mechanism underlying this longitudinal relationship.
authors.affiliation: Centre for Health Initiatives, University of Wollongong, Wollongong, NSW, Australia. cmagee@uow.edu.au.
authors.forename: Christopher
authors.initials: C
authors.lastname: Magee
authors.forename: Peter
authors.initials: P
authors.lastname: Caputi
authors.forename: Don
authors.initials: D
authors.lastname: Iverson
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015444:Exercise; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000453:epidemiology / Q000209:etiology*; D012890:Sleep; D012959:Socioeconomic Factors; D013690:Television / Q000706:statistics & numerical data*
keywords: Mediation; Obesity; Sleep; Television viewing