A recent study by University of Washington researchers found that an increase in sleep duration by 34 minutes was associated with a 4.5 percent increase in the median grades of sophomore students and an improvement in their attendance, suggesting that even an extra half hour of sleep a day may be more beneficial than you think.
When the Seattle, Washington, school district moved back the start of the school day from 7:50 a.m. to 8:45 a.m. a few years back, the scientists took the opportunity to observe the benefits of a later start. The researchers studied sophomores from two public high schools in Seattle by measuring their sleep and academic performance before the schedule change and after. The study participants were all taking the same classes.
"This change was implemented for the 2016-2017 academic year and allowed us to conduct a pre-/post-study in which we measured sleep-wake cycles using wrist activity devices during the spring of 2016 (pre) and the spring of 2017 (post)," the study explains. Each student involved in the study wore an Actiwatch and kept a sleep journal. An actiwatch is a device that tracks and provides information about sleep/wake patterns.
The results, which were published last week in the Science Advances journal, found that students who started school later got an average of 35 more minutes of sleep a night. They were more likely to get to school on time, and their grades improved.
"There is evidence that adolescents in most industrialized societies do not achieve the recommended approximately nine hours of daily sleep during school days, which is consistent with estimates that in the past 100 years, sleep has shortened by about one hour in children," the study notes.
"Our study demonstrates a lengthening in the median daily sleep duration from 6 hours and 50 minutes to 7 hours and 24 minutes, restoring the historical sleep values present several decades before evenings within brightly lit environments and with access to light-emitting screens were common among teenagers. These results demonstrate that delaying high school start times brings students closer to reaching the recommended sleep amount and reverses the century-long trend in gradual sleep loss," the authors observe.
In a recent interview with Boston Magazine, US sleep expert Charles Czeisler of Harvard Medical School noted that under the current US school system, in which students have to get up very early, it's impossible for teenagers to get the amount of sleep they need.
"They're [teens] going to be chronically sleep-deprived, and we know sleep deprivation adversely affects learning. We set aside a decade for them to get the education that they need, and then we put a bowling ball around their legs so they can't achieve what they could be achieving," Czeisler said during the interview, also adding that students who don't get enough sleep are at a greater risk of depression and suicide.