A study of teens published online in Pediatrics on April 8 found that each additional hour of sleep was associated with a reduced body mass index (BMI), especially for teens with higher BMIs. Increasing sleep from 7.5 to 10.0 hours per day at age 18 predicted a reduction in the proportion of overweight adolescents by 4 percent. “The study is further evidence to support that getting more sleep each night has substantial health benefits during this crucial developmental period,” lead author Jonathan A. Mitchell, PhD, said in a Penn news release.