Sleep deprivation could double the risk of obesity, a study has found.

Researchers from the University of Warwick analysed data on 28,000 children and 15,000 adults.

They found that shorter sleep duration was associated with almost a two-fold increased risk of being obese for both groups.

The research also suggested that those who sleep less have a greater increase in body mass index and waist circumference over time and a greater chance of becoming obese over time.

Lead researcher Professor Francesco Cappuccio said: "The 'epidemic' of obesity is paralleled by a 'silent epidemic' of reduced sleep duration with short sleep duration linked to increased risk of obesity both in adults and in children.

"These trends are detectable in adults as well as in children as young as 5 years."

He points out that short sleep duration may lead to obesity through an increase of appetite via hormonal changes caused by the sleep deprivation.

Lack of sleep produces gherlin, which stimulates appetite, and it also produces less leptin, which suppresses the need to eat.

However, Prof Cappuccio says more research is needed to understand the mechanisms by which short sleep is linked to chronic conditions of affluent societies, such as obesity, diabetes and hypertension.

Francesco Branca, the Regional Adviser for nutrition and food security in the World Health Organization (WHO) Regional Office for Europe, said: "This is an interesting piece of research putting together different lifestyle aspects with food choices.

"We need more research on the obese environment - the integration between medical research and socio-political research is something we should be exploring more."