Rising levels of obesity could be linked to a lack of sleep in childhood, a researcher said today.
Dr Shahrad Taheri said children and adolescents were getting fewer hours of sleep than they used to, affecting the levels of hormones that control appetite and energy expenditure.
The researcher at Bristol University blames shorter sleep periods among youngsters on increased use of televisions, mobile phones and computers.
Research suggests that most TV viewing by children happens near bedtime, and can disrupt sleep, he said.
Writing in the Archives of Disease in Childhood from the British Medical Journal, Dr Taheri said that removing electronic gadgets from children's bedrooms could be part of a strategy to tackle obesity.
"Sleep is probably not the only answer to the obesity pandemic, but its effect should be taken seriously, as even small changes in energy balance are beneficial," he said.
Dr Taheri said studies have indicated that sleep loss could disturb the production of hormones that control the desire for calorie-rich foods, hunger and energy expenditure.
For example, the level of ghrelin, a hormone released by the stomach to signal hunger, was found to be 15% higher in people who have only five hours sleep a night than those gaining eight hours.
Lack of sleep also leads to tiredness during the day, which may mean people do not do enough physical activity, a major contributor to obesity.
The link between obesity and sleep deprivation appears to be particularly strong in children and young people, Dr Taheri said.
The Avon Longitudinal Study of Parents and Children in the UK found in the 1990s that insufficient sleep at 30 months predicted obesity at age seven.
And teenagers, who need more sleep at a critical period of development, are also at risk, with evidence showing that as little as two or three nights of sleep restriction could have an "profound effect" on young adults, Dr Taheri said.
He suggested: "An obesity prevention approach in children and adolescents that promotes a healthy diet, physical activity and adequate sleep could be adopted."
Good sleep could be promoted by removing televisions and other electronic items from children's bedrooms and ensuring a strict, regular bedtime routine, he said.
"Ensuring adequate sleep in children and adolescents may not only help fighting against obesity, but could have other added health and educational benefits - for example improvements in academic performance," he said.