A study shows that getting a later start to school is helping high school students in Seattle, Washington, get a little more sleep. In the study, teenagers did add 34 minutes of sleep a night. Students got more sleep, and had better grades, better test scores, and fewer absences.
The Seattle School District changed the start time from 7:50 a, m, to 8:45 a, m, in 20lin high schools and most middle schools, At the same time, many other American schools are also changing to later start times so that the teens who don't have enough sleep can get more sleeping time.
The scientists asked about 28,000 students and parents to complete surveys about school start times, the children's sleep habits and daytime sleepiness. The first survey was completed four months before a Denver school district changed the time that school began. The next survey was completed six months after the change, which allowed older students to start later. High school began about 70 minutes later at 8:20 a.m. Middle school started anywhere from 40 to 60 minutes later at 8:50 . m. And elementary school started 60 minutes earlier at 8 a. m. They made the final survey 18 months after the adjustments.
Both students and their parents answered questions about when children went to bed and woke on weekdays and weekends, how long they slept on weekends and how they felt during the day.
The elementary school students didn't experience much difference in the amount of time they slept before and after the school start time changed. The middle school students woke much later. High school students received the most sleep after the change, waking 45 minutes later. What the parents reported about their children showed the same trends (趋势). Many experts believe that starting school later does improve students' sleep but some think that students will still not get enough sleep no matter when school begins.
