title: Epidemiological study of sleep habits among four-and-a-half-year-old children in Japan.
abstract: BACKGROUND
  To date, only limited epidemiological data on the sleep habits of young children in Japan have been available. This study used representative samples to examine the sleep habits of four-and-a-half-year-old children in Japan.
  
  
  METHODS
  We used data from a nationwide cross-sectional survey. A member of each subject's family was asked to complete the questionnaire. The questionnaire included personal characteristics, sleep habits, and lifestyle.
  
  
  RESULTS
  The data for 39,813 subject children (collection rate: 74.3%) were analyzed. The mean value of total sleep duration, night-time sleep duration, and daytime napping duration was 10 h 40 min 30 s, 9 h 53 min 0 s, and 46 min 24 s, respectively. The prevalence of daytime napping was 45.8%. Those whose total sleep duration was less than 10h accounted for 13.7% of the sample. The factors associated with high odds ratios for shorter total sleep duration were: living in a less populated area, long hours spent watching television, longer maternal work hours, and attending preschool.
  
  
  CONCLUSIONS
  In attempting to devise ways of improving the sleep habits of young children, the lifestyles of both the children and their parents must be considered.
authors: Division of Public Health, Department of Social Medicine, Nihon University School of Medicine, Japan.
authors: Maki
authors: M
authors: Ikeda
authors: Yoshitaka
authors: Y
authors: Kaneita
authors: Shuji
authors: S
authors: Kondo
authors: Osamu
authors: O
authors: Itani
authors: Takashi
authors: T
authors: Ohida
mesh_terms: D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006184:Habits; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D012737:Sex Factors; D012890:Sleep; D013997:Time Factors