THURSDAY, June 13, 2019 (HealthDay News) -- It's a no-brainer -- not getting enough sleep makes it harder for kids to learn. And a new study finds that starting school later in the morning can help teens be more alert during the day.
In 2017, the Cherry Creek School District in Greenwood Village, Colo., changed start times from 8 a.m. to 8:50 a.m. for its middle school students and from 7:10 a.m. to 8:20 a.m. for high school students.
That change gave middle schoolers 31 more minutes of sleep, while high schoolers got 48 minutes more, the researchers said.
"Biological changes in the circadian rhythm, or internal clock, during puberty prevents teens from falling asleep early enough to get sufficient sleep when faced with early school start times," said lead researcher Lisa Meltzer. She's an associate professor of pediatrics at National Jewish Health in Denver.
"This study provides additional support that delaying middle and high school start times results in increased sleep duration for adolescents due to later wake times," she added in a news release from the American Academy of Sleep Medicine.
For the study, more than 15,000 students completed online surveys about their sleep habits before and after the new starting time.
Besides getting more sleep, students said they were more alert for homework.
Before the time change, 46% of middle schoolers and 71% of high schoolers said they were too tired to do homework. After the change, that dropped to 35% and 56%, respectively.
At the same time, scores that measured academic engagement rose significantly.
"The study findings are important because getting enough sleep is critical for adolescent development, physical health, mood, and academic success," Meltzer said.
The report was published online recently in the journal Sleep, and the findings were presented Wednesday at a meeting of the American Academy of Sleep Medicine in San Antonio, Texas.
For more about school starting times, visit the U.S. Centers for Disease Control and Prevention.