April 25, 2018
3 min read

Middle schoolers have improved sleep habits with later school start times

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Daniel Lewin, PhD, DABSM, CBSM
Daniel S. Lewin

Later school start times benefit the sleep schedules of adolescents, with seventh and eighth graders reporting a longer duration of sleep and less sleepiness during the day, according to findings published in the Journal of School Health.

“When [teenagers] do not sleep on a regular schedule — at the optimal time for the optimal amount of time — there can be serious short- and long-term effects on health, particularly cardiometabolic health, mental health, safety and learning,” Daniel S. Lewin, PhD, DABSM, CBSM, associate director of sleep medicine at Children’s National Health System, told Infectious Diseases in Children. “The bottom line is that sleep health is one of the essential pillars of good health behavior that includes optimal nutrition, sleep duration and timing and regular exercise.”

“This disconnect has led to several groups, including the AAP, the American Medical Association, the CDC and the United States Department of Education to recommend later start times for both middle and high schools,” Lewin and colleagues wrote.

To examine the relationship between sleep habits in middle school-aged children and school start times, the researchers conducted a study in which students attending grades seven and eight answered questions in online surveys. Some adolescents included attended eight schools that started at approximately 8 a.m. (n = 630). Students from three schools that started at approximately 7:23 a.m. also were included (n = 343). All schools were located within a suburban school district.

Once data were collected, Temkin and colleagues calculated doubly robust inverse probability of treatment-weighted regression estimates that focused on how later school start times impact bedtimes, duration of sleep and sleepiness during the day.

The average duration of sleep for students who began school at an early start time received 8 hours and 9 minutes of sleep on average. These students demonstrated shorter durations of sleep when compared with those of students who began school at later times (average duration: 8 hours, 23 minutes). When the researchers accounted for demographic variables, they observed a significant association between start time and sleep duration, with those beginning school later having 17 more minutes of sleep (b = 0.29; P < .001).

Temkin and colleagues observed that when duration of sleep was considered, there was a 37-muinute average difference between the two start times and an increase of sleep duration by about 46% of the time spent during the delayed school start time.

All students who participated in the study went to bed at 9:45 p.m. on average. Those who started school early had an average bedtime of 9:43 p.m., and those who started school at a later time had an average bedtime of 10:02 p.m. Once the researchers took demographic variables into consideration, they observed that bedtime and school had a significant relationship, with those starting school earlier having a bedtime set 15 minutes before those who start school later (b = 0.25; P < .001).

When adolescents were not in school on the weekend, an average sleep duration of 10 hours and 6 minutes was observed, with an average bedtime of 11:06 p.m. Although a relationship was observed between sleep duration, bedtimes and school start times, no significant connection was observed regarding weekend sleep duration or bedtimes and school start times.

Additionally, adolescents who attended schools with later start times were less likely to feel sleepy during the day (b = –0.34; P < .001). These students also reported being wide awake or not struggling to stay awake during activities up to 2 weeks before survey completion (b = 0.09; P < .001). According to the researchers, students in eighth grade, black students and females were more likely to report daytime sleepiness.

Temkin and colleagues observed that demographic characteristics played a significant role in adolescent sleep habits and school start times. In this cohort, students in eighth grade received 25 minutes less sleep than other students. Female students received an estimated 10 minutes less sleep, and those with two or more reported races exhibiting a 22-minute decrease in sleep duration than white students. Furthermore, students who spoke a language other than English at home had a sleep duration shortened by 27 minutes on average.

When the effect that demographics have on betimes was examined, the researchers observed a significant relationship between grades, races and language spoken in the home; no significant relationship was found between sex and bedtime. Temkin and colleagues speculate that this may imply that earlier wake-up times may be associated with the difference in sleep duration rather than bedtimes.

“When you see a teenager who has mood, attention, social and learning problems, as well as overweight, ask about their sleep health, timing and duration, sleep schedule regularity and snoring,” Lewin said. “Teenagers who are struggling with early school start times and sleep problems should maintain a relatively regular schedule on weekends, should not nap for longer than 20 minutes in the afternoon, should not drink caffeinated beverages after noon and should sleep in as late as possible on weekday mornings without using the snooze button.” – by Katherine Bortz

Disclosures: The authors report no relevant financial disclosures.