Sleep expert tells why high schools need later start times

Delaying the morning start time in secondary schools improves adolescents’ sleep and, consequently, their health and function, said Dr. Maida Chen, professor of pediatrics at the University of Washington School of Medicine and a sleep medicine specialist at Seattle Children’s Hospital. Ten years after Seattle delayed start times at middle and high schools, she discusses what the change has meant for students. 

There's pressure from many sides for schools to start earlier, said Chen. It’s better for working parents who drop off their children before work, for example, and it gives athletic teams more time for practices. 

Early start times, however, don’t match adolescents’ biology.  

As children experience hormonal changes and puberty, their circadian rhythms shift later. For many, their natural bedtime shifts to 11 p.m. or midnight. When schools start early, that doesn’t leave time for them to get enough sleep. 

“In childhood in particular, much of the brain is active during sleep,” said Chen. 

Insufficient sleep affects adolescents' mood, behavior, academic performance, judgment and growth. Those changes can affect the people around them, as well. 

“It is hard to parent a that-much-grumpier teenager,” said Chen. 

Fifteen years ago, Seattle Public Schools wanted to use the same buses to transport students to different schools. As a result, some middle and high schools shifted to start before 8 a.m. More students from those schools began coming to Seattle Children’s sleep disorders clinic. They couldn’t wake up on time and accumulated unexcused absences. She diagnosed many of them with delayed sleep phase syndrome but also saw the problem as more structural than individual. 

“There are certain things we can do to keep the circadian rhythm shift more aligned with bell times, but it’s not easy to fight body physiology,” Chen explained. 

She and others worked with Seattle Public Schools to change the school day’s structure. They recommended that middle and high schools delay starting until after 8:30 a.m., the time recommended by the American Academy of Pediatrics and Centers for Disease Control and Prevention. In exchange, some elementary schools could start earlier; those students’ circadian rhythms haven't shifted yet, so earlier start times don't affect their sleep as much. 

In 2016, Seattle Public Schools changed start times so the majority of middle and high schools began at 8:45 a.m. The Iglesia Lab at the University of Washington found that high school students, on average, got a half hour more sleep, improved grades and improved attendance as a result. 

Nationally, only 29.8% of middle schools and 28.1% of high schools begin at 8:30 a.m. or later. To prioritize adolescents’ health and growth, that percentage needs to be higher, Chen said.

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