The University of Michigan research finds parents are split almost down the middle on whether they support delays in school start times that might permit their 13- to 17-year-olds to sleep later on school days.

The results come from a nationally representative survey through the U-M C.S. Mott Children’s Hospital Poll on Children’s Health. In it, 554 parents whose teens all start school before 8:30 a.m. shared opinions on how much sleep their children need and whether later school start times are a good idea. The study was published in the Journal of Clinical Sleep Medicine, the journal of the American Academy of Sleep Medicine.

“We found that parents underestimated how much sleep their children needed, and only about half agreed with existing recommendations that school start times should be later,” says lead researcher Galit Dunietz, Ph.D., MPH, a postdoctoral research fellow in neurology at Michigan Medicine.

School start time recommendations issued by the American Academy of Sleep Medicine and the American Academy of Pediatrics take into account teens’ natural circadian rhythms. Teens often have a daily inner clock that runs longer than 24 hours.

This makes it difficult for them to go to sleep when the rest of the family does. And they often find it challenging to get up early and be on time for a school day that starts before 8:30 a.m.

“Many teens would do fine if they could go to bed late and sleep late in the morning,” says senior study author and neurologist Ronald Chervin, M.D., M.S., director of the U-M Sleep Disorders Center. “But they can be late to school or become chronically sleep-deprived when classes start early every weekday.”