Delayed School Start Times Shown to Increase Adolescent Sleep Duration, Study Finds

Delayed school start times were shown to increase sleep duration among adolescents and lessen the need for catch-up sleep during the weekend, which may assist in addressing nationwide sleep deficits in these populations. Published today in JAMA Pediatrics, researchers highlight that while the National Sleep Foundation recommends 8 to 10 hours of sleep per night for adolescents, more than half of those aged 16 years nationwide get less than 7 hours.

Sleep behavior among adolescents has become a major issue of focus that both parents and education systems have sought to improve in past years. In a prior study, insufficient sleep in 2 adolescent groups aged 6-12 and 13-17 was linked with impaired behavioral and social well-being. These factors were shown to affect school performance, as well as physical and mental health, stressing the vital need for effective interventions.

One issue that may be contributing to these widespread sleep deficits are school start times, which researchers note start early, and may leave adolescents with their current sleep bottleneck. While some states, such as California, move up school start times, researchers indicate that fewer than 15% of US high schools start at 8:30 AM or later, and 42% start very early, at 8 AM or before.

Researchers sought to investigate the association of delayed school start times with sleep duration, timing, and quality. They examined an adolescent cohort of 455 students (225 girls [49.5%] and 219 boys [48.1%]; mean [SD] age at baseline, 15.2 [0.3] years) from 5 public high schools in the metropolitan area of Minneapolis and St Paul, Minnesota. All 5 schools started early at baseline (7:30 am or 7:45 am) with 2 schools later delaying their start times by 50 and 65 minutes (experimental group).

The observational cohort study followed students’ sleep duration, timing, and quality via wrist actigraphy from grade 9 (May 3 to June 3, 2016) through grade 11 (March 15 to May 21, 2018), with 2 follow ups occurring in 2017 and 2018. Difference-in-difference design, linear mixed-effects models were used to estimate differences in changes in sleep time between the experimental and control schools.

Compared with students who attended control schools, those attending experimental schools exhibited an additional mean 41 objectively measured minutes of night sleep at follow-up 1 (95% CI, 25-57) and 43 at follow-up 2 (95% CI, 25-61). Delayed start times were not associated with falling asleep later on school nights at follow-ups.

Additionally, students attending experimental schools were shown to have a decreased need for catch-up sleep during the weekend as they showed a mean difference-in-differences change in weekend night sleep of −24 (95% CI, −51 to 2) minutes from baseline to follow-up 1 and −34 (95% CI, −65 to −3) minutes from baseline to follow-up 2 compared with control students.

“The present study’s results suggest that later start times could be a durable and transformative strategy for dealing with the epidemic sleep insufficiency among adolescents,” said the study authors.

Reference

Widome R, Berger AT, Iber C, et al. Association of delaying school start time with sleep duration, timing, and quality among adolescents [published online April 27, 2020]. JAMA Pediatr. doi: 10.1001/jamapediatrics.2020.0344.