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10-04-2013 | Metabolism | Article

Sleep the weight away


Free abstract

medwireNews: Teenagers with shorter sleep duration are more likely to have a higher body mass index (BMI) than those who sleep for longer, show study findings.

"The psychosocial and physical consequences of adolescent obesity are well documented, yet the rate has more than tripled over the last four decades," said study investigator Jonathan Mitchell (University of Pennsylvania, Philadelphia, USA) in a press statement.

"The study is further evidence to support that getting more sleep each night has substantial health benefits during this crucial developmental period," he added.

As reported in Pediatrics, Mitchell and colleagues followed up a group of 1390 adolescents every 6 months from the age of 14 to 18 years to assess the impact of average sleep duration on BMI.

Each additional hour of sleep was linked with decreases in BMI in all of the adolescents. These ranged from a mean reduction of 0.04 kg/m2 for those in the 10th percentile for BMI to 0.27 kg/m2 for those in the 90th, with greater reductions per extra hour of sleep seen for those with a higher BMI at baseline.

The researchers estimated that increasing the average duration of sleep from 7.5 to 10.0 hours per day at the age of 18 years would reduce the proportion of teenagers falling into the overweight or obese (BMI >25 kg/m2) category by 4%. This amounts to approximately 500,000 less overweight adolescents in the USA.

"Educating adolescents on the benefits of sleep, and informing them of sleep hygiene practices have shown to have little impact on adolescent sleep duration," said Mitchell.

"One possible solution could be for high schools to delay the start to the school day. 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. Since our study shows increasing sleep by an hour or more could lead to a lower BMI, delaying the start of the school day could help to reduce obesity in adolescents," he suggested.

medwireNews ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013

By Helen Albert, Senior medwireNews Reporter