THURSDAY, April 15, 2021 (HealthDay News) -- Starting the school day a little later helps middle and high school students get more and better sleep, according to a new study.
The research is based on annual surveys of about 28,000 elementary, middle and high school students and their parents. The surveys were completed before and two years after school start times were changed.
Changes to sleep cycles during puberty make it harder for teens to fall asleep. With early school start times, many don't get enough rest.
In the study, middle schools pushed their start times back by 40 to 60 minutes; and high schools began the day 70 minutes later. Meanwhile, elementary schools started an hour earlier.
Participants were asked about students' typical bedtime and wake time on weekdays and weekends, and also about quality of sleep and daytime sleepiness.
The surveys revealed that the high school students benefited most from starting school later. They were able to get an extra 3.8 hours of sleep a week. More than 10% said they were sleeping better and 20% reported less daytime sleepiness.
Because they were getting more sleep on weeknights, high school students didn't feel as great a need to play catch-up on weekends, the study found. Their additional weekend sleep fell from an average of just over 2 hours to 1.2.
Meanwhile, middle school students reported getting an extra 2.4 hours of sleep a week with a later school start time. They also had a 12% drop in reported daytime sleepiness.
Later start times had no effect on elementary school students, according to findings published April 15 in the journal Sleep. The study was led by Lisa Meltzer, a pediatric psychologist at National Jewish Health in Denver.
Sleep is a key factor in students' overall health, social development and school performance, but lack of sleep is common among children and teens.
Meltzer and her co-authors said the new study offers the strongest evidence to date that moving elementary school start times to 8 a.m. has no negative effect on students.
As students return to in-person learning, it is important for school officials to consider healthy start times for all youngsters, they said.
The U.S. Centers for Disease Control and Prevention has more on school start times.
SOURCE: Sleep, news release, April 15, 2021