03/06/2014 08:48 am ET Updated May 06, 2014

Is It Time to Start School Later?

Teenagers are notoriously difficult to rouse in the morning, as parents know well. Our teens' struggle to "rise and shine" in the early morning hours isn't really about adolescent obstinacy or laziness. Teens are biologically driven to these sleep-in, stay-up-late schedules -- routines that can frustrate parents and make early school mornings challenging for everybody. What if the remedy lies not in attempting to change teens' sleep routines, but in making adjustments to the requirements of their daily schedules?

New research indicates that even a small delay in school start times can have a significant effect on teenagers' sleep, as well as on their waking mood and daytime habits. Researchers at the Bradley Hasbro Children's Research Center in Rhode Island studied the impact of a 25-minute delay in school start time on adolescents' sleep patterns, daytime sleepiness, and mood, as well as daytime habits including caffeine consumption. The study included 197 high school students attending an independent boarding school. Researchers collected data about sleep habits during a winter term when school start time was delayed from 8 a.m. to 8:25 a.m. They found this modest adjustment to the beginning of the school day was associated with significant changes to sleep and waking mood:

  • Students' overall sleep duration increased significantly when their school day began 25 minutes later. Total sleep time increased by an average of 29 minutes.
  • With the later start to the school day, the percentage of students sleeping 8 or more hours per night more than doubled, from 18 percent to 44 percent.
  • Younger students (grades 9 and 10), as well as students who were sleeping less at the study's outset showed the greatest benefit from the 25-minute adjustment to school start time.
  • Students also experienced significant reduction in daytime sleepiness, as well as improvements to mood, during the later school-start period.
  • Caffeine use among students also reduced during this period.
  • Students' daytime activities -- time spent doing homework, and time engaged in extracurricular activities including sports -- did not change with the alteration in the start to the school day.
  • When the students' school start time returned to 8 a.m. after the end of the winter term study period, students lost the sleep gains they had achieved. Their sleep duration returned to levels that researchers observed at the study's outset.

These results add compelling new information to the body of evidence that suggests students' health and sleep would be well served by adjusting school schedules to be more aligned with adolescent sleep-wake cycles, and to better meet their sleep needs.

Teenagers are particularly vulnerable to insufficient sleep, for several reasons. Adolescents' sleep requirements are greater than adults -- teens need roughly 9-10 hours of nightly sleep, compared to a general recommendation of 7-8 hours for adults. Their busy schedules, with homework, sports and extracurricular activities, as well as time spent socializing make this 9-plus hour nightly sleep demand difficult to meet. Teens also experience biological changes that make them prone to sleep deficiencies and can make an early start to the school day particularly challenging. During adolescence, sleep cycles undergo a shift toward a later phase, leaving teenagers biologically more inclined to stay up later in the evening and sleep later in the morning. Teens tend to experience reduced alertness during daytime hours, and heightened alertness in the evening. This adolescent circadian rhythm shift includes a delay in the release of the sleep hormone melatonin, which begins its rise later in the evening than for younger children or adults. The morning downturn in melatonin levels also happens later, contributing to teens' difficulty in rising early. Adolescents are more prone to daytime tiredness and also to irregular sleep routines -- sleeping less during the week and catching up with extended sleep on the weekends.

Studies show insufficient sleep is common among teenagers, and the impact of sleep loss is broad, affecting learning and academic performance, as well as mood and behavior. Short on sleep, high school students are more likely to perform worse on tests, and receive lower grades. They are also more at risk for a range of unhealthy behaviors, including smoking and drinking, as well as physical violence. Teens with chronic sleep deprivation are also more prone to depression.

Other research has shown that changes to school schedules -- even modest changes, like the current study -- can have a dramatic effect on sleep, mood, and daytime functioning for teenagers:

  • Changing school start time from 8 a.m. to 8:30 a.m. resulted in a substantial rise in sleep time -- an average of 45 minutes of additional sleep -- among high school students in Rhode Island, according to research. The percentage of students sleeping fewer than 7 hours nightly decreased by 79.4 percent, while the percentage of students sleeping 8 or more hours nightly increased from 16.4 percent to 57.4 percent. Students experienced improvements to mood and motivation levels, and reductions in daytime sleepiness. Attendance improved, while visits to the school health center for complaints related to fatigue dropped.
  • Researchers studied the effects of rolling back start time to an earlier hour with a group of students through 9th and 10th grades. In the 9th grade, school started at 8:25 a.m. In the 10th grade, the school day began at 7:20 a.m. Researchers found that students went to bed at the same time even after the transition to the earlier start, and they slept less overall. In 10th grade, students also experienced significantly more daytime sleepiness.
  • Though adolescents' sleep patterns and sleep needs are distinct from younger children, it's not only teenagers who could benefit from a later start to the school day. Researchers in China spent four years studying primary school students' sleep habits, and sleep's relationship to academic performance. They found that well more than half of students -- 64.4 percent -- experienced daytime sleepiness, and that this daytime fatigue was linked to lower academic performance, as well as to diminished attention span and reduced motivation for learning. Delaying the school day by as little as 30 minutes increased sleep duration and reduced daytime sleepiness significantly.

Its time to stop requiring adolescents to adhere to a schedule that contributes to widespread sleep deficiencies -- a schedule that is at odds with students' basic biological inclinations. Adjusting the start of the school day is complicated. Many parents and school officials will likely have their own schedules and routines affected by any changes. But even small delays in favor of students can have significant effects on the quantity and quality of their nightly rest, their physical and emotional health, and their performance at school during the day. With all that at stake, it's worth giving these changes serious consideration.

Sweet Dreams,
Michael J. Breus, PhD
The Sleep Doctor®

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