Sleep study links irregular sleep, late bedtimes to worse grades in high school

ByRose Weldon

Fact checked byCarol L. DiBerardino, MLA, ELS

Key takeaways:

A study linked irregular sleep and late bedtimes to worse grades and behavioral issues among high schoolers.
Suspension and expulsion were more common if a student woke up later or varied their bedtime.

A study identified late or varied bedtimes as risk factors for worse grades and behavioral issues among high school students, according to results published in Sleep.

“There's plenty of research that examines the effects of sleep duration — such as how much sleep someone gets — on academic functioning, but not as much on other dimensions of sleep, such as sleep quality and sleep variability across the week,” Gina M. Mathew, PhD, a post-doctoral associate in public health at Stony Brook Medicine in Stony Brook, New York, told Healio.

“We examined whether multiple dimensions of sleep measured objectively were linked with academic performance and school-related behavioral problems in a large sample,” Mathew said.

Mathew and colleagues analyzed data from nearly 800 adolescents participating in Princeton University and Columbia University’s Future of Families and Child Wellbeing Study, a sample of children born in U.S. cities with a population exceeding 200,000. Participants aged 15 years were asked to wear a wrist accelerometer — a device that records the wearer’s movements — for a week so that study staff could estimate their sleep patterns, and to provide information on grades and any school-related behavioral issues.

The authors examined the data through the lens of sleep timing, sleep efficiency and sleep variability in relation to academic function.

In analytical samples which “ranged from 774 to 782 depending on the outcome,” participants with more variable bedtimes had a greater chance of receiving a D or lower (OR = 1.29) during the last grading period compared with those with more consistent bedtimes.

Adolescents who went to bed later, got up later or varied the number of hours they slept per night received fewer A grades. Adolescents were more likely to be suspended or expelled in the last 2 years if they got up later, varied the number of hours they slept each night or if they varied the time they went to bed each night.

“It was somewhat surprising that neither sleep duration nor efficiency were linked to academic performance or behavioral problems,” Mathew said. “These dimensions of sleep are certainly important for a number of aspects of emotional and physical health but were not related to our academic measures of interest in this sample.”

Mathew said it is important for providers to encourage parents to keep consistent bedtimes and wake times for their children — even in high school, when adolescents often desire more freedom.

“For pediatricians, asking about sleep habits and making appropriate recommendations at regular checkups is an important tool in maintaining optimal pediatric sleep health,” Mathew said.

She said future studies could obtain academic records directly from schools and measure sleep and academic functioning across time, which would allow researchers to examine whether good sleep actually predicts better academic functioning within the same adolescent. On a larger scale, she recommended that school districts start school later.

“School districts should move high school start times to 8:30 a.m. or later, which would allow for sufficient sleep during the school week and for students to perform when at their best,” Mathew said. “Research could subsequently examine if adolescent academic functioning improves following a district's shift to later school start times.”