Babies, toddlers and pre-school children who sleep for less than 10 hours a night are more likely to be overweight when they are older, research has found.
Experts believe a lack of sleep causes an imbalance in the hormones that control appetite, meaning those who do not get enough sleep are more likely to feel hungry and crave calorie-rich snacks during the day.
Previous research has linked sleep deprivation with obesity in adults and teenagers, but this is one of the first to look at very young children.
Researchers from the Universities of Washington and California looked at the sleeping habits of almost 1,000 children under the age of five.
They found those who have less than ten hours' sleep were twice as likely to be overweight five years later, with some even clinically obese.
The study, published in the American journal the Archives of Paediatrics and Adolescent Medicine, also looked at children aged five to 13 but did not find any significant trends.
Childhood obesity has doubled over the past 20 years and a quarter of secondary school pupils are now judged to be so overweight their health is at risk. Around 10 per cent of six year olds are obese – with rates predicted to rise significantly
over the next few years.
Experts believe sleep, or lack of it, could be a major cause of this, with the average child now sleeping for an hour less than they did 30 years ago.
The researchers concluded: 'Insufficient night-time sleep among infants and pre-school-age children appears to be a lasting risk factor for subsequent obesity.'
Last year Chinese researchers looked at more than 5,000 youngsters and found that those who were able to catch up on sleep at the weekend were far less likely to pile on the pounds.
Scientists have also found a link between lack of sleep and type-2 diabetes.
Last year Canadian researchers discovered those who did not get the optimum seven or eight hours' sleep a night were two and a half times more at risk from the illness.
Do you think there's a link between later bedtimes and obesity?