Delayed High School Start Times in Seattle: Positive Outcomes

In the 2016-2017 school year, the Seattle Public School District took a risk. Based on policy recommendations published in a 2014 report by the American Academy of Pediatrics (AAP), district officials implemented a system-wide delay in high school start times. Here’s the AAP claim that triggered the change:

“[We] recognize insufficient sleep in adolescents [is] an important public health issue that significantly affects the health and safety, as well as the academic success, of our nation’s middle and high school students…a substantial body of research has now demonstrated that delaying school start times is an effective countermeasure to chronic sleep loss and has a wide range of potential benefits to students with regard to physical and mental health, safety, and academic achievement.”

Their practical advice: don’t start middle or high school before 8:30 am. Their reasoning: with the onset of puberty, adolescent circadian rhythm – i.e. the natural cycle of wakefulness and sleep, related to the presence of light, dark, and various hormonal factors – shifts the natural sleep clock back by a couple of hours. Whereas prepubescent children start to fade around 8:30 pm and are generally ready to sleep by around 9:30 or 10:00, if not earlier, adolescents and late adolescents tend to be wide awake at 10:00 pm and not ready for sleep until around midnight.

Seattle school officials got the message. They moved back school start times to 8:45 am across the district, with some schools starting as late as 8:55 am. At the same time, they took another important step: they approved a study by researchers at the University of Washington to gauge the effects – positive or negative – of the changes.

The overall takeaway?

Later start times help high school students in several areas.

One Hour Makes A Difference

First, let’s take a quick look at the AAP statement. It proposes later school start times benefit adolescent physical health, mental health, safety, and academic achievement. The mechanism by which these benefits arise – theoretically – is increased sleep time. We extrapolate that from the following language in the AAP statement: “…delaying school start times is an effective countermeasure to chronic sleep loss.”

Which begs the question: if school starts later, isn’t it likely that adolescents will just stay up later?

It’s a good question. One would think teens would see later school start times as an opportunity to stay up later. But the data show otherwise. On average, the students in the study increased their sleep time by over half an hour. They went from six hours and fifty minutes a night to seven hours and twenty-four minutes. Which, we should point out, is still a full two hours short of the physician recommended nine to nine and a half hours teens per night teens need for optimal health.

Now, let’s take a look at how researchers ran the study. They analyzed the sleep patterns, grades, and attendance of two groups of high school students from two different schools who took the same 10th grade biology class first thing in the morning. They gathered data from the first group over six-week period in the spring of 2016, the year before the time change, and gathered data from the second group over a six-week period in the spring of 2017, seven months into the school year with the new start times. Students wore special wristwatches to record darkness/light and sleep/wakefulness. They also answered questionnaires regarding sleepiness and mental well-being. The schools provided the data on grades and attendance.

Here’s what they found.

Delayed School Start: Three Positive Outcomes
  • Average sleep time increased by of over half an hour for students in both schools
  • Grades improved by 4.5% for students in both schools
  • Absentee rates decreased by 2% in one of the schools
  • Tardiness rates decreased by 2% in one of the schools

Note: The decreased absentee and tardiness rates appeared in the school comprised of a greater proportion of economically disadvantaged students (88% compared to 31%) and a greater proportion of ethnic minorities (68% compared to 7%). Researchers noted that these facts warrant further investigation but offered no substantial explanations for the significant differences.

The Natural Clock

The team of researchers from the University of Washington point out that over the past one hundred years, average sleep times for adolescents have decreased by about one hour. Explanations include the universal presence of electricity in the developed world, the near-universal access to light-emitting screens, such as television, smartphones, and computers, and the gradual move toward earlier start times for high schools, which generally begin an hour or half an hour earlier than elementary schools. All these factors put teens between a rock and a hard place.  Internally, their natural sleep patterns shift later by couple of hours, while externally, the demands of school shift earlier by an hour or so.

For some students, a 7:45 am  or 7:55 am start time means getting up as early as 5:00 am. For an adolescent whose circadian clock keeps them up until midnight, this is not ideal. In fact, it’s a formula for decreased cognitive performance, higher levels of circulating stress hormones, and increased levels of moodiness and irritability. Any parent of teens – or anyone who works with teenagers – knows moodiness, irritability, and stress come with the territory. And that’s without chronic sleep deprivaiton. Forcing early school start times on them makes little sense. It actually exacerbates some of the more challenging aspects of puberty teens work daily to modulate. That’s what the AAP concluded before publishing their report, and that’s what Seattle Public School officials understood before taking the risk to implement their plan, which involved a mountain of logistical reshuffling to accomplish.

Time to Follow Their Lead

So far, the reward proves worth the risk and justifies the practical headaches: sleep time and grades both improve. Students show up on time and get more out of their first-period classes than before. Now, what remains to be seen is if the rest of the country will follow suit, and shift high school start times to an hour that increases chances of student engagement, participation, and improved academic achievement.