The relationships between sex, age, geography and time in bed in adolescents: a meta-analysis of data from 23 countries

Sleep Med Rev. 2010 Dec;14(6):371-8. doi: 10.1016/j.smrv.2009.12.002. Epub 2010 Mar 6.


Objectives: To quantify the relationships between age, sex and country of residence and sleep time (time in bed) in young people aged 9-18 years.

Methods: Thirty studies of sleep patterns in healthy adolescents from the last 30 years in 20 countries were reviewed. Monte Carlo simulation generated pseudo-data where only summary statistics were available. Raw and pseudo-data were combined, generating a total of 92,977 data points. A mixed model, clustering on countries, analysed data for school and non-school days separately.

Results: Sleep time varied with sex, age and geographical region. School day sleep differed slightly between boys and girls, girls sleeping 11 min/night more than boys (p = 0.003). On non-school days, girls slept 29 min more each day (p = 0.003). Sleep time declined with age, - 14 min/day per year of age (school days), and seven min/night per year of age (non-school days). Large differences between countries, showed adolescents from Asian countries sleeping 40-60 min less each night than Americans, and 60-120 min less than Europeans.

Conclusion: Sex, age, geographical region and day type interact and predict sleep patterns in adolescents. One consistent trend is the increasing gap between sleep on school days and non-school days as adolescents get older.

Publication types

  • Meta-Analysis
  • Review

MeSH terms

  • Activities of Daily Living*
  • Adolescent
  • Adolescent Behavior*
  • Asia / epidemiology
  • Attitude to Health
  • Child
  • Child Behavior*
  • Cluster Analysis
  • Europe / epidemiology
  • Female
  • Health Behavior
  • Humans
  • Life Style
  • Male
  • North America / epidemiology
  • Quality of Life
  • Sleep Deprivation / epidemiology
  • Sleep Wake Disorders / epidemiology*
  • Sleep*
  • Social Environment
  • Socioeconomic Factors
  • Wakefulness*