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Most of us should receive more sleep. But a recent study has found that getting more sleep may help stem the obesity epidemic. Researchers have found that, if every adolescent received 8 to 10 hours of sleep a night, that could result in as many as 500,000 fewer obese adolescents.

Previous studies have found a link between loss of sleep and weight gain and obesity. However, those studies could not figure out how to account for various factors, like level of physical activity and amount of television watched. Researchers from the University of Pennsylvania's Perelman School of Medicine did so by studying 1,000 Philadelphia students between their freshman and senior years of high school. Every six months, the students were asked to record their sleep habits. At the same time, the researchers recorded the students' height, weight and body mass index.

 "What we found in following these adolescents is that each additional hour of sleep was associated with a reduced BMI for all participants, but the reduction was greater for those with higher BMIs," study author Jonathan A. Mitchell said in a statement. "The study is further evidence to support that getting more sleep each night has substantial health benefits during this crucial developmental period."

For example, students who were in the 10^th percentile for body mass index only saw a slight decrease, 0.07 kg/m², for every extra hour of sleep they received. The benefit increased, however, for students in the 50^th percentile or higher. Those in the 50^th percentile or higher lost about 0.17 kg/m² for every hour of sleep gained; in fact, students in the 90^th BMI percentile lost 0.28 kg/m² for each extra hour of sleep. That link stayed accurate even when researchers adjusted for factors like physical activity and television viewing habits.

Researchers affiliated with the study do not believe that it is enough to remind students to get more sleep. Instead, they believe that schools should opt to start later. "Previous research has shown that delaying the start of the school day even by 30 minutes results in a 45-minute per day increase in sleep," Mitchell stated.

The study was published in the journal Pediatrics.