Lack of sleep may be the most important factor in determining whether a child is likely to become overweight, according to researchers from Université Laval in Quebec City.

In an article published in the latest edition of the International Journal of Obesity, the researchers report that the risk of becoming overweight is 3.5 times higher in children who get less sleep than in those who sleep a lot.

The scientists measured the weight, height, and waist size of 422 grade school students aged 5 to 10, and obtained nformation on the children's lifestyle and socioeconomic status through phone interviews with their parents.

The researchers determined that 20 percent of the boys and 24 percent of the girls were overweight based on body mass index. Children who slept less than 10 hours a night were 3.5 times more at risk of being overweight than those who slept 12 or more hours.

No other factor analyzed in the study -- parental obesity, parents' level of education, family income, time spent in front of the TV or computer, regular physical activity -- had as much of an impact on the likelihood of obesity as time spent sleeping.

“Lack of sleep lowers the level of leptin, a hormone that stimulates metabolism and decreases hunger. In addition, short nights of sleep boost the concentration of ghrelin, a hormone that increases hunger,” theorized Professor Angelo Tremblay.

“It's ironic that part of the solution to obesity might lie in sleep, the most sedentary of all human activities. In light of this study's results, my best prescription against obesity in children would be to encourage them to move more and to make sure they get enough sleep,” Tremblay said.

Other sources: Université Laval'