Clear benefit emerges for students who switched from early to late school start

While most of the nation’s kids are out of school because of the Covid-19 pandemic, this might be time to rethink school start times, particularly for teens. According to a recent study, delaying high school start times led to more sleep for adolescents, who tend to be vulnerable to sleep deficits and related problems.

“In schools that shifted their start time later, objective measurement shows that students slept longer on school nights at both 1 and 2 years after the change, relative to students in schools that maintained an early start time throughout the observation period,” wrote Rachel Widome, PhD, MHS, an epidemiologist with the University of Minnesota School of Public Health, and colleagues, in JAMA Pediatrics.

Despite recommendations that adolescents sleep 8-10 hours per night, more than half of U.S. 16-year-olds regularly get only 7 hours or fewer per night, with typical bedtimes for 12th graders falling after 11 p.m. on weekdays, experts noted. High school start times, which often don’t line up with adolescent circadian biology, can exacerbate the issue. According to Widome and colleagues, no previous study had measured adolescent student sleep at multiple points over a span of time that encompassed a shift in school start times.

“Unfortunately, high schools in the United States tend to start quite early, typically earlier than primary schools, leaving adolescents with their current sleep bottleneck,” Widome and colleagues wrote. “In the present study, we aimed to determine whether a shift to a later start time was associated with objectively measured adolescent sleep duration, quality, and timing during an extended follow-up period.”

The observational cohort study encompassed 5 suburban and rural public high schools in Minnesota’s Twin Cities region. Researchers followed 455 students (225 girls [49.5%] and 219 boys [48.1%]; mean [SD] age at baseline 15.2 [0.3] years) from grades 9-11. At the study’s baseline in 2016, all 5 participating schools started at times that Widome and colleagues deemed to be early (either 7:30 am or 7:45 am). Follow-ups at 1 year and 2 years included students at 2 schools that pushed back start times by 50 and 65 minutes after baseline; 3 of the schools began at 7:30 am throughout the study.

Widome and colleagues gathered much of their data using wrist actigraphy—a device similar to a wristwatch that tracks sleep patterns, movement, and light. Participants were instructed to wear the device at all times, except during contact sports or while in the water. Students also self-reported sleep patterns and other data.

Students in the later-starting schools slept a mean of 41 (95% CI 25-57) and 43 (95% CI 25-61) minutes longer on school nights at the 1- and 2-year follow-ups, respectively, than their counterparts at earlier-starting schools.

Further, delayed-start students slept approximately 24 fewer minutes on the weekends (95% CI −51 to 2) at 1 year and 34 fewer minutes (95% CI −65 to −3) at 2 years compared with early-starting students.

All students in the study had later sleep onset on school nights in grades 10 and 11 compared with 9th grade. At the same time sleep onset in later-starting schools did not vary substantially from that found in students at the other schools, with onset occurring 2 (95% CI −13 to 16) and 16 (95% CI −1 to 33) mean minutes later in the delayed-start students at the respective 1- and 2-year follow-ups.

“Concurrent with the increase in school night sleep duration, those attending delayed-start schools had a decrease in weekend night sleep duration, suggesting lesser accumulated sleep debt with the later start times,” Widome and colleagues wrote. “Sleep fragmentation, sleep efficiency, and sleep latency onset appeared to be minimally affected or unaffected by the shift to a later start time.”

Study limitations identified by the research team included the study’s lack of randomization to condition, meaning a correlation between student sleep and school decisions to change start times could be responsible for the results.

One potential area for future research, Widome and colleagues wrote, could focus on the question of how school start times might affect health status and academic performance. In the meantime, however, they concluded that the new data “suggest that later start times could be a durable and transformative strategy for dealing with the epidemic sleep insufficiency among adolescents.”

In an accompanying editorial, Indiana University School of Medicine pediatrics researchers Erika Cheng, PhD, MPA, and Aaron Carroll, MD, MS, who is also an editor for JAMA Pediatrics but like Cheng was not affiliated with the study, called for a new mindset when it comes to adolescents’ sleep habits. While noting that costs and logistics, among other issues, can make this sort of change more challenging than it might seem at a glance, such changes could nevertheless lead to improved productivity and quality of life in this population.

“We ask our adolescents to perform well in school, build positive relationships, learn to drive, and avoid risk-taking behaviors; to do so, they need emotion regulation and executive functioning skills that depend on regions of the brain that are vulnerable to sleep deprivation,” Cheng and Carroll wrote. “We often blame adolescents for their not getting enough sleep, but much of that is not their fault—it is ours.”

  1. A 2-year observational study found adolescents got roughly 40 more minutes of sleep per weeknight when high schools moved to later start times.

  2. Weekend sleep patterns also suggested lesser sleep deficits after the shift.

Scott Harris, Contributing Writer, BreakingMED™

No source appearing in this article disclosed any relevant financial relationship with industry.

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Topic ID: 85,138,730,138,192,925