Delaying high school start times by nearly an hour resulted in more sleep for students and increased academic performance, researchers said. in a study conducted in three Seattle schools.
Following implementation of the later school start time in the 2016-2017 school year, median daily sleep duration during school days increased from 6 hours and 50 minutes the previous year to 7 hours and 24 minutes, and survey findings suggested that students were less sleepy on school days, according to Horacio de la Iglesia, PhD, of the University of Washington, and colleagues.
Also, median grades increased 4.5% after implementing the delayed start, and first-period absenteeism declined from 15.5 to 13.6 per student-year (P<0.0001), the researchers reported in the journal Science Advances.
The decision by the Seattle School District to delay start times for secondary schools from 7:50 to 8:45 starting in the 2016-2017 academic year gave de la Iglesia and colleagues a unique opportunity to study the impact of such a move on student sleep, grades, and attendance.
Because the decision was announced more than a year before the change was implemented, the researchers were able to measure sleep-wake cycles of students before and after it occurred.
Numerous studies have shown changes in the circadian system during puberty that cause teens to naturally stay up later at night and sleep later in the mornings. Many studies have shown that teens tend to be chronically sleep deprived.
Although the strategy of delaying school start times in an effort to increase teen sleep times has been debated for more than a decade, Seattle’s school system is among the largest in the country to try it.
The study involved sophomores enrolled in three science classes at two Seattle area public high schools. Sleep-wake cycles were measured over two-week periods for each year studied using a wrist-worn actigraphy device.
During the spring of 2016 (pre-change) and the spring of 2017 (post-change) students wore the watches while sleeping during the two-week recording phase of the study. They also completed a sleep diary (used for validation) and they completed several questionnaires, including the Beck Depression Index II, the Epworth Sleepiness Scale Questionnaire and the Munich and Horne-Ostberg Chronotype Questionnaires.
“Although it is highly likely that increased sleep was the cause for reduced sleepiness, it is much harder to attribute causality for 4.5% higher grades on increased sleep; nevertheless, it is certainly reasonable that students who are better rested and more alert should display better academic performance,” de la Iglesia told MedPage Today.
Another finding was that attendance and late arrival improved mainly at one school that had mostly economically disadvantaged students. At the other, which had a more affluent student population, less change was seen in those parameters.
“After the change was made the two schools were much more similar to each other in terms of attendance and late arrival,” de la Iglesia said. “This suggests — although we can’t prove it yet — that delayed school start times could benefit lower income students more and contribute to reducing the achievement gap. That is very exciting.”
Even though the findings appear to show a clear benefit to later high school start times, de la Iglesia said it may take time for other large school systems to follow Seattle’s lead.
“One of the main obstacles is cultural — the idea that teens are sleeping later because they are lazy, which isn’t true. They are not lazy. They are just following their biological timing, and that isn’t going to change,” he said.
He added that economic and institutional obstacles have also prevented school systems from adopting later high school start times. Many school systems don’t have enough buses to make the change and coaches have fought it because later start times mean later dismissals, which interfere with sports practice schedules.
“It is certainly not an easy thing to do, but it could have huge benefits,” de la Iglesia said. “It is pretty clear that high school students will get more sleep if school start times are later.”
The study was supported by government grants and foundation funding. De la Iglesia reported having given talks on adolescent sleep physiology to Seattle-area school boards and other groups, which may have influenced the district’s decision to implement the later start times.