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Starting school just 30 minutes later was associated with significant improvements in reported adolescent sleep times, mood and health, according to a new study released Monday.
The study, which is published in the July issue of Archives of Pediatrics & Adolescent Medicine, adds to evidence that allowing teenagers to sleep later in the morning has many benefits.
While some high schools have shifted to later start times over the past decade the vast majority still begin the school day by 8 a.m. or earlier.
The study’s lead author, Judith Owens, the director of the pediatric sleep clinic Hasbro Children’s Hospital in Providence, explained that biological changes in teenagers’ circadian rhythms causes a shift in sleep onset and wake times relative to younger children. Along with a biological shift in the sleep-wake cycle, other factors such as after-school activities and homework can push bedtimes later.
“On a practical level this means that the average adolescent has difficulty falling asleep before 11 p.m.,” Owens said. Teenagers still need slightly more than nine hours of sleep each night, which would call for an ideal wake time of about 8 a.m.
... At the end of the study, the average sleep duration on school nights increased by 45 minutes to nearly eight hours. Not only did the average student sleep about 30 minutes later in the morning, many reported going to bed about 15 minutes earlier.
Owens said some students reported that they felt so much better sleeping later that they also decided to try to go to bed earlier to get more sleep. The number of students who reported getting at least eight hours of sleep increased from 16.4% to 54.7%. There were also changes in mood with the percentage of students who rated themselves as depressed or “at least somewhat unhappy” falling to 45% from 66% before the later starting time, while the percentage of students who reported feeling annoyed or irritated throughout the day fell to 63% from 84%.
http://online.wsj.com/article/BT-CO-20100705-704870.html
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