title: Determinants of sleep patterns in healthy Japanese 5-year-old children.
abstract: BACKGROUND
  Early childhood is an important period for the development of sleep patterns; studies of sleep patterns in young preschool children may help elucidate the mechanism of associated mental/physical conditions and later sleep problems.
  
  
  OBJECTIVE
  The aim of this study was to investigate intrinsic and extrinsic independent variables associated with sleep patterns in preschool children using actigraphy. Forty-eight 5-year-old children from two types of nurseries, which accommodate children with (Type A) or without (Type B) in-home caregivers, were invited to undergo a 7-day actigraphic sleep study.
  
  
  RESULTS
  Compared with weekdays, both sleep onset time and sleep end time were later on weekends (28 and 17 min later in average, respectively). On weekdays, cultural lessons were associated with a later sleep onset time (22 min later); female gender, sports lessons and fixed bathing times were related with an earlier sleep end time (17, 21 and 17 min earlier, respectively); sports lessons were also associated with higher sleep efficiency (3.7% higher). During weekends, unfixed bedtimes and daytime naps were related with a later sleep onset time (73 and 54 min later, respectively); male gender, Type A nursery and daytime naps were associated with a later sleep end time (33, 37 and 34 min later, respectively); sports lessons were associated with higher sleep efficiency (3.6% higher).
  
  
  CONCLUSIONS
  Our current findings suggested that both intrinsic and extrinsic factors, such as gender, child care, lifestyle and after-nursery lessons, influence the establishment of sleep patterns in young preschool children. Further investigation of these independent variables may help establish a strategy for predicting and preventing sleep disorders later in life.
authors.affiliation: Centre for Developmental & Cognitive Neuroscience, Department of Paediatrics & Child Health, Kurume University School of Medicine, Fukuoka, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Iwata
authors.forename: Osuke
authors.initials: O
authors.lastname: Iwata
authors.forename: Akiko
authors.initials: A
authors.lastname: Iemura
authors.forename: Mizue
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Toyojiro
authors.initials: T
authors.lastname: Matsuishi
mesh_terms: D056044:Actigraphy; D044466:Asian People; D002656:Child Day Care Centers; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D012890:Sleep / Q000502:physiology*