The Benefits of Later School Start Times

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In a previous post, I mentioned that the COVID-19 pandemic would provide much useful information about sleep habits, sleep needs, and the daily functioning of children. With the vast majority of schools conducting all or some classes online during the 2020-21 school year, the reduction of time required to get ready for school, along with the elimination of morning commutes, meant that students would not necessarily have to get up as early to start the school day.

A study just published in the journal Sleep provides data from over 5,000 students in grades 6-12 from all over the U.S. Students were either in (a) in-person classes; (b) online live classes with teacher interactions; or (c) online but without live classes or teacher interactions. Some students had “hybrid” instructional models with some in-person days and some online. Students reported the time their classes started in 30-minute intervals from “before 7:00 AM” to “after 9:30 AM.” They also reported their bedtimes and rise times, bedtime and rise time consistency (day-to-day variation), and bedtime routines, including the use of technological devices before going to bed.

How Start Times Affected Sleep

As expected, the time that the school day started (whether in-person or online) affected how much sleep was reported. With earlier starts, both bedtimes and wake times were earlier. On average, bedtimes for online live classes were around half an hour later than for in-person classes. For middle school students, a start time between 8:30 and 9:00 AM resulted in a greater number of students getting sufficient sleep (defined as at least 9 hours).

Of note is that only about a third of middle school students had start times this late. Only around half of the high school students who got sufficient sleep had in-person start times later than 8:30. There was considerable night-to-night variability in sleep, especially in the hybrid models, since students had to get up earlier for in-person days. In past research, more variability in sleep schedules has been associated with negative mood and behavior outcomes in children and adolescents.

These data have implications for the hard decisions many school districts have faced regarding start times for school. A great many districts have followed the recommendation of the American Academy of Pediatrics for start times no earlier than 8:30 AM for middle and high school students and the results reported here indicate that such start times afford the opportunity for more sleep. The results also indicate that even for online instruction, starting at 8:30 or later is more optimal. Reducing day-to-day variation in start times for online classes is also a goal that school districts should consider.

What Does This Mean for Younger Children?

As I have mentioned numerous times in previous posts, start times for younger children (grades K-6) have received very little attention from researchers, and this recent study is illustrative of that point. In a majority of cases when school districts move middle and high school start times later, elementary start times are moved earlier, and we have no idea if very early start times are beneficial or at least not harmful for young children. Since younger children need more sleep, having an earlier start requires an earlier rise time to allow for preparation and commute.

There are individual differences in sleep needs by age, but guidelines typically call for 10-13 hours for preschoolers age 3-5 and 9-12 hours for children 6-12. For example, if a first or second grader’s school begins at 7:30 AM, they might have to be asleep before 8:00 PM to get sufficient sleep before waking early enough to get ready and commute to school.