Delayed Start Time Improves Outcomes, Reduces Tardies and Absences

• By Dian Schaffhauser
• 03/11/19

When Seattle Public Schools delayed middle and high school start times by almost an hour, students slept longer and researchers found a link in higher median grades and improved attendance. The project was carried out by researchers at the University of Washington and the Salk Institute. Results were published in Science Advances last December.

The Seattle school district began a year-long exploration of the impact of making changes in school start times in 2014, around the same time that state legislation mandated an increase in the number of instructional hours high schoolers received. As with many such decisions around the country, a change in bell times would have to address three areas — breakfast and lunch services, before- and after-school programs and athletics — where people were most concerned about the logistical challenges. But nothing outweighed the argument that teenagers would benefit "from later start times resulting in more sleep, better health, increased academics and improved truancy rates," as one official letter to the school community put it. For most of the affected schools, that meant shoving back start times from 7:50 to 8:45.

While that change was in the works, researchers at UW thought they'd conduct a pre- and post-study to measure sleep-wake cycles using wearables. They issued Actiwatch Spectrum Plus from Philips Respironics for two weeks during spring 2016 and 2017 to groups of sophomores attending the same science class in each of two public high schools. The watches were programmed to collect data in 15-second segments for 14 days; and the students were told to press a marker button on the watch each time they went to sleep and woke up. They also completed a daily online diary in which they answered questions about sleep, how they were awakened, if they had taken naps, if they'd removed the watch and anything else that came to them. (At the same time, these science students could study their own predictions about their sleep patterns as part of their high school classwork.)

As might be expected, based on previous research projects, overall, there was a median shift in sleep duration of 34 minutes, along with an associated increase in the median grades of participants by 4.5 percent.

Regarding attendance, while students in one school showed no difference in the percent of absents and tardies, the other high school had "significantly fewer" of both in the late-start year compared to the early-start year. "Notably," the researchers wrote, that second school had "many more economically disadvantaged students (88 percent) and ethnic minorities (68 percent)" than the first one did (31 percent and 7 percent, respectively).

The research report is openly available on Science Advances.