Even small delays in school start times can benefit teen health

Friday, December 7, 2018

School desk with clock, books, pencils, apple
Starting high school even 10 minutes later can result in significant sleep benefits for adolescents, says a new UWaterloo COMPASS study.

The study, which examined data from more than 27,000 Ontario students participating in COMPASS found that even small delays of 10 minutes could result in almost a half hour more of sleep, something that one-third of adolescents don’t get enough of.

Contrary to concerns some people had about screen activity increasing if school were to start later, the small delays in start times did not result in any significant changes in screen time use or amount of physical activity.

“In this natural experiment, we looked at schools that had changed their start times, either by delaying or advancing them, and super-imposed them onto the longitudinal data from students’ responses of how much time they were spending on sleep, screens, or physical activity before, during and after the school policy changes,” said Scott Leatherdale, a professor in the School of Public Health and Health Systems and principal investigator of COMPASS.

“The study supports the knowledge that teens have greater sleep needs in the morning, which conflicts with many school start times.”  

The study found that five-minute changes, either starting earlier or later, did not make a big difference to the students’ sleep. Ten-minute delays after a 9 a.m. start time also made little difference.

COMPASS is a longitudinal study that surveys more than 70,000 students in grades 9 through 12 at more than 120 Canadian schools. COMPASS is the first study internationally to use a longitudinal research design to evaluate how changes in programs, policies or built environment resources are related to changes in youth health outcomes such as substance use, obesity and mental health over time.

The study, “School start time changes in the COMPASS study: associations with youth sleep duration, physical activity, and screen time,” authored by Karen Patte, Wei Qian, Adam Cole, Guy Faulkner, Jean-Philippe Chaput, Valerie Carson and Scott Leatherdale, was published in Sleep Medicine.