title: Predictors of shorter sleep in early childhood.
abstract: OBJECTIVE
  The aim of this study was to identify socio-demographic and home environmental predictors of shorter sleep in early childhood, and to examine whether effects were mediated by the timing of bedtime or wake time.
  
  
  METHODS
  Participants were from Gemini, a British birth cohort of twins, and included 1702 children; one randomly selected from each twin pair. Parents reported night-time sleep duration at an average age of 15.8 months (range 14-27 months) using a modified version of the Brief Infant Sleep Questionnaire. Multiple logistic regression models were used to identify predictors of shorter sleep for this study.
  
  
  RESULTS
  Using a cut-off of <11 h a night, shorter sleep was reported in 14.1% of children. Lower maternal education, non-white ethnic background, being male, low birth weight, living in a home with >1 older child and watching >1 h of TV in the evening were independently associated with shorter sleep. Mediation analyses showed that associations between education, ethnicity, evening TV viewing and sleep were driven predominantly by later bedtimes, while sex differences were driven predominantly by earlier wake times in boys.
  
  
  CONCLUSIONS
  In this sample, multiple environmental factors were associated with shorter sleep in young children, with several operating predominantly through later bedtime. An emphasis on the importance of an early and consistent bedtime could help promote healthy sleep and reduce inequalities in child health.
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: McDonald
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Wardle
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Clare H
authors.initials: CH
authors.lastname: Llewellyn
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Cornelia H M
authors.initials: CH
authors.lastname: van Jaarsveld
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: Abigail.fisher@ucl.ac.uk.
authors.forename: Abigail
authors.initials: A
authors.lastname: Fisher
mesh_terms: D002675:Child, Preschool; D015331:Cohort Studies; D004522:Educational Status; D005006:Ethnicity / Q000706:statistics & numerical data; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D012307:Risk Factors; D012737:Sex Factors; D012892:Sleep Deprivation / Q000453:epidemiology / Q000209:etiology*; D011795:Surveys and Questionnaires; D013690:Television / Q000706:statistics & numerical data; D006113:United Kingdom / Q000453:epidemiology
keywords: Bedtime; Behaviour; Child; Predictors; Sleep; Wake time
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