Longer Sleep Linked to Lower BMI for Teens

Let them sleep.

That’s the advice of researchers who studied the sleep habits of teens struggling with obesity.

A new study from the Perelman School of Medicine at the University of Pennsylvania found that increasing the number of hours that adolescents sleep may lower the prevalence of obesity for that age group.

In fact, fewer hours of sleep was associated with greater increases in body mass index, according to the study published in the latest issue of Pediatrics.

So how much sleep does a teen need?

The researchers suggest that sleep should be increased to 10 hours per day, especially for adolescents “in the upper half of the BMI distribution,” a news release from the University of Pennsylvania School of Medicine states.

“The psychosocial and physical consequences of adolescent obesity are well documented, yet the rate has more than tripled over the last four decades,” said lead author Jonathan A. Mitchell, PhD, in the news release. “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. The study is further evidence to support that getting more sleep each night has substantial health benefits during this crucial developmental period.”

The four-year study followed 1,000 high school students from the Philadephia area from their freshman year through senior year. Every six months, their sleep patterns were documented.

Based on the results of their study, the authors believe that increasing sleep from 8 to 10 hours per day at age 18 could result in a 4 percent reduction in the number of adolescents with a BMI above 25 kg/m2. That would equate to about 500,000 fewer overweight adolescents, according to the news release.

But to see results, it may take more than a parent encouraging their child to sleep longer.

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

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