No evidence for an epidemiological transition in sleep patterns among children: a 12-country study

Objective To examine the relationships between socioeconomic status (SES; household income and parental education) and objectively measured sleep patterns (sleep duration, sleep efficiency, and bedtime) among children from around the world and explore how the relationships differ across country levels of human development. Design Multinational, cross-sectional study from sites in Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom, and the United States. Setting The International Study of Childhood Obesity, Lifestyle and the Environment. Participants A total of 6040 children aged 9-11 years. Measurements Sleep duration, sleep efficiency, and bedtime were monitored over 7 consecutive days using waist-worn accelerometers. Multilevel models were used to examine the relationships between sleep patterns and SES. Results In country-specific analyses, there were no significant linear trends for sleep duration and sleep efficiency based on income and education levels. There were significant linear trends in 4 countries for bedtime (Australia, United States, United Kingdom, and India), generally showing that children in the lowest income group had later bedtimes. Later bedtimes were associated with lowest level of parental education in only 2 countries (United Kingdom and India). Patterns of associations between sleep characteristics and SES were not different between boys and girls. Conclusions Sleep patterns of children (especially sleep duration and efficiency) appear unrelated to SES in each of the 12 countries, with no differences across country levels of human development. The lack of evidence for an epidemiological transition in sleep patterns suggests that efforts to improve sleep hygiene of children should not be limited to any specific SES level.