Later school start time improves teens' sleep and mood

September 1, 2010

Investigators examined the effect of delaying school start time by 30 minutes on teenagers' sleep patterns and behavior, daytime sleepiness, and mood.

Investigators examined the effect of delaying school start time by 30 minutes on teenagers' sleep patterns and behavior, daytime sleepiness, and mood. The study was conducted at a coeducational independent high school in Rhode Island with day and boarding students. About 200 students, from grades 9 through 12, completed the Sleep Habits Survey online, once before the school start time was adjusted and again 2 months after the school day start time was changed from 8:00 AM to 8:30 AM. The Sleep Habits Survey is a comprehensive 8-page self-report survey that includes questions about typical sleep and wake behaviors during the previous week.

The start time delay was associated with a 45-minute increase in sleep duration on school nights (7 hr, 52 min vs 7 hr 7 min). This increase was associated not only with an expected later waking time but also a significantly earlier (18 min) bedtime on school nights. The percentage of students getting fewer than 7 hours of sleep decreased by 79.4% from the first survey to the second survey, and those reporting at least 8 hours of sleep increased from 16.4% to 54.7%, respectively. Boarding and day students did not differ significantly with regard to school night sleep duration.

The relative proportion of students reporting dissatisfaction with the quality or length of their sleep also decreased significantly from the first survey to the second survey, although the percentage of students reporting difficulty falling asleep at least several times a week did not change much. Results of the second survey also showed a reduction in daytime sleepiness, fatigue, and depressed mood. Most health-related variables, including visits to the school health center for fatigue-related complaints, and class attendance also improved from the first survey to the second (Owens JA, et al. Arch Pediatr Adolesc Med. 2010;164[7]:608-614).

Because the students were surveyed in December and March, I was ready to attribute their changes in mood to the change of season. Who, living in the Northeast, isn't happier in spring than in the depths of winter? Many of the other changes described would be hard to explain by season alone, however. And both these results and those from other studies reviewed in an accompanying editorial to this study are impressive. But altering school start times may not be simple. Schedules of whole families and communities revolve around when children go to and are out of school. Nonetheless, it may be worth the effort to accomplish results like these. -Michael Burke, MD