Obese adolescents go to bed later and sleep less than their lighter contemporaries. This is the finding of a study published in the April issue of Australian and New Zealand Journal of Public Health.

Professor Tim Olds and his colleagues at the University of South Australia explored the sleep patterns of 9-18 year old Australians on different days of the week.

Other findings that may help parents understand their adolescent children included: * On average, girls slept more, because of earlier bedtimes. * As adolescents grow older, they sleep less. * Underweight children went to bed significantly earlier than those of normal weight.

Prof. Olds said the 'cause and effect' between sleep patterns and weight was unclear.

"The sleep patterns we found sit comfortably with the theory that short sleep duration predisposes towards obesity," he said. "However, there may also be some third factor that contributes to both overweight and short sleep duration."

This third factor may be linked to the time adolescents spend in front of computer or TV screens or low physical activity. "Sleep intervention studies examining the relationship between screen time, weight status and sleep would help to clarify these issues.

Source: Wiley - Blackwell