Starting school later may have helped some disadvantaged students in Seattle get better grades, according to a new study. The research adds to a mounting pile of evidence that suggests we’re making teens get up way too early.
Sleep experts have long said that teenagers tend to fall asleep late and need up to 10 hours of sleep per night, compared to only about eight hours for adults. As result, the American Academy of Pediatrics calls early school start times a “public health issue” that affects academic success. For a study published today in the journal Science Advances, scientists at the University of Washington monitored the sleep of students at Seattle high schools before and after their schools changed their start time to 8:45AM from 7:50AM. Using wrist monitors to track activity, they found that the later start time really did result in more sleep (as opposed to teens just staying up later than ever). Not only that, but students at an economically disadvantaged high school also had higher grades and fewer absences after the start time changed.
Final grades for kids in the school with less money were 4.5 percent higher than before
School start times have increasingly become a question of public policy. This year, California legislators pushed for a bill that would require schools to start no earlier than 8:30AM. (California Gov. Jerry Brown ultimately vetoed the bill, believing that these changes should be addressed on a community level.) For any school, implementing this change is a big endeavor. When schools start later, the schedules of teachers, parents, coaches, and bus drivers have to change, too, so it’s important to know how helpful the later start time would actually be.
That’s where scientific research comes in. For today’s study, the scientists collaborated with biology teachers at two different high schools in Seattle. Ninety-two sophomores from both biology classes wore wrist monitors for two weeks. (Though these wrist monitors, which recorded light and activity level every 15 seconds, are an imperfect measure of activity, they’re far more accurate than self-reporting.) A year later, after the start time had changed, the scientists repeated the experiment with 88 new sophomores drawn from those same two classes.
The wrist monitors revealed that all of the students slept more — a median of 34 minutes more per night — after the start time changed. The students also reported feeling less sleepy and more alert. Importantly, final grades for kids in the school with less money were 4.5 percent higher than before. Before, those kids had more tardies and absences than the kids at the wealthier school. After, that gap disappeared.
This effect is correlational. “Although it is highly likely that increased sleep was the cause for reduced sleepiness, it is much harder to attribute causality for 4.5 percent higher grades on increased sleep,” the researchers write. “Nevertheless, it is certainly reasonable that students who are better rested and more alert should display better academic performance.” Even if there isn’t a direct link between improved grades and sleep in this case, it’s an intriguing result that that points to one possible way to help close the economic gap in education: let the teens sleep in.