Children and teenagers who keep a set bedtime every school night are half as likely to be tired in class, according to a new report from the Centers for Disease Control and Prevention. But some of the most academically vulnerable groups of students are also those most likely to have inconsistent sleep times.
Nationwide, a third of children sleep less than the amount recommended by the American Academy of Sleep Medicine: 9 to 12 hours for children ages 6 to 12, and 8 to 10 hours for teenagers ages 13 to 18.
Researchers used 2020 data from a National Center for Health Statistics survey to analyze weeknight bedtimes for children ages 5 to 17. Only 47 percent of them always went to bed at the same time, but more than 4 out of 5 children went to sleep at the same time most school nights.
However, the CDC found that among children living below the poverty line, Black children, and those in single-parent households, more than a quarter didn’t keep regular bedtimes on school nights.
That’s a problem, sleep experts say, because setting specific sleep and wake-up times, particularly for children and adolescents, can help regulate core systems for sleep.
Two interconnected systems govern sleep. At the most basic level, the longer it has been since you’ve slept, the more the body will release the sleep-regulating hormone melatonin, and the sleepier you’ll feel. The second system, known as the circadian cycle, changes body hormones, temperature, and activity levels in response to changes in light and dark levels.
Circadian rhythms may change throughout the year in response to light levels, and also shift to about an hour later in adolescence. The CDC found elementary- and middle school-age children were 10 percentage points more likely to have consistent sleep times than older students.
Set sleep times and pre-bedtime periods can also help families to manage students’ screen time, which has been shown to disrupt student sleep by mimicking natural sunlight.
Harvard Medical School studies have found that exposure to so-called “blue light” devices—including smartphones, tablets, and laptops—in the late afternoon and evening can disrupt sleep cycles by as much as six to eight hours. That’s equal to the “jet lag” caused by a flight from Washington, D.C., to Honolulu.
While families set and enforce students’ sleep times, experts say school policies can help encourage more-consistent school night sleep habits. For example, the Minnesota Sleep Society, which works with schools, recommended school leaders:
- Include sleep education in health class and parent workshops.
- Make electronic homework submission deadlines no later than early evening, such as 5-6 p.m., rather than 11:59 p.m.
- End school activities such as sports practices or clubs no later than 10 hours before morning bus pick-up the next day. (Later adolescent wake-up times may also affect early morning practices and bus pick-ups at the secondary school level.)
- Ask teachers to coordinate test and major project deadlines to help students avoid late-night “cramming.”
- When giving electronic devices to students, provide guidelines and if possible parental controls to turn them off at least one hour before bed.
- Assess students for sleep deprivation as part of developing an individualized education program.