Pushing back high school start times could have benefits for typically sleep-deprived teens, both physically and mentally, a new study suggests.
Researchers delayed the start time of a single school in Rhode Island by a half hour. After the change, students got 45 minutes more snooze time on average and reported feeling less fatigued and depressed. Absences during first period and visits to the health center for fatigue also declined.
However, since the study involved only one school, the results might not necessarily apply to the general population, the researchers say. The school was also not typical in that about 80 percent of students were boarding there.
Nonetheless, the findings add to a growing body of evidence suggesting that postponing school starts can have a number of payoffs for teens. While the researchers don't advocate that all high schools across the country change their schedules, they say it is something to ponder.
"Even a modest delay in school start time, a half hour, can have a very significant impact on quality of life and health and mood of adolescents," said study researcher Dr. Judith Owens, director of the Pediatric Sleep Disorder Center at Hasbro Children's Hospital in Providence, RI. Although such a change can be challenging in terms of coordinating a schedule shift, "I think the evidence really is mounting that it's an undertaking that's well worth at least considering," Owens said.
Teens and sleep
While adolescents still need just as much sleep as younger kids, about nine hours, social and biological changes take place around high school that result in less shuteye for teens.
Around the time of puberty, our sleep-wake cycle shifts by as much as two hours, Owens said, so that a teenager might naturally fall asleep at 11 p.m. instead of 9 p.m., and wake up at 8 a.m. instead of 6 a.m. Such a transition makes it hard to get ready for the 8 a.m. or earlier start time that many high schools have.
In addition, homework, jobs, extracurricular activities and social time can also eat away at time spent sleeping.
Less sleep is associated with a number of bad outcomes for teens, including obesity, an increase in car accidents and attention and memory problems.
Most studies looking at the effects of school start time on teens have either compared two different schools or looked at the impact over different years. Owens and her colleagues wanted to see what would happen in the same group of students over a relatively short period of time.
They had 201 students in grades 9 through 12 fill out questionnaires about their sleep habits and moods before and after the time change. The school delayed its start time from 8 a.m. to 8:30 a.m. for two months.
Among the findings:
- Sleep time on school nights increased by 45 minutes. This was due to both earlier bedtimes and later waking times.
- The percentage of students getting at least eight hours of sleep increased from 16.4 percent to 54.7 percent.
- The percentage reporting less than seven hours of sleep decreased by 79.4 percent.
- Fewer students reported feeling "unhappy or depressed," (65.8 percent initially compared with 45.1 percent after the change).
- Fewer students visited the health care center for symptoms of fatigue (15.3 percent initially vs. 4.6 percent after)
- Absences and tardies to first period decreased by 45 percent.
The fact that students got more sleep after the time change suggests that delaying school start might not simply result in kids pushing back their bedtimes and therefore getting the same amount of sleep. Some students said that they were even inspired to go to bed earlier, because they became aware of just how beneficial a little extra sleep can be.
More research needed
Since the study didn't have a control group — a group of students who didn't change their school start time — the researchers don't know if the benefits they saw were really due to the time change, or from other factors.
However, the researchers note their study population was more uniform than the average high school, with relatively similar requirements for homework and extracurricular activities. So there was less of a chance that differences in other factors influenced these results.
More studies should be conducted in populations throughout the country to get a better idea of how to address the issue, the researchers say.
The results were published in the July issue of the Archives of Pediatrics & Adolescent Medicine, a journal of the American Medical Association.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.