In search of lost sleep: Secular trends in the sleep time of school-aged children and adolescents

Background: Sleep deficits are associated with a wide range of detrimental physical and mental health outcomes. There is concern that children are not getting enough sleep, and that sleep duration has been declining. However, evidence is sparse. Methods: A systematic review of world literature was conducted to locate studies reporting the sleep duration of children aged 5-18 years. Monte Carlo simulation was used to generate pseudodata from summary data, which were combined with raw data and analysed by linear regression of sleep duration on year of measurement at the age x sex x day type x country level. Results: Data were available on 690,747 children from 20 countries, dating from 1905 to 2008. From these data, 641 regressions were derived. The sample-weighted median rate of change was -0.75 min nightly per year, indicating a decrease of more than 1 h per night over the study period. Rates of change were negative across age, sex and day type categories, but varied according to region, with Europe, the USA. Canada and Asia showing decreases and Australia, the UK and Scandinavia showing increases. Conclusion: Over the last 103 years, there have been consistent rapid declines in the sleep duration of children and adolescents. (C) 2011 Elsevier Ltd. All rights reserved.