Each fall, groggy teenagers resign themselves to another year of fighting their body clocks so they can get to class on time. It's well known that teens who don't get at least eight hours of sleep a night face a slew of problems. That's why both the American Academy of Pediatrics and the Centers for Disease Control recommend shifting middle- and high-school start times to 8:30 a.m. or later. Yet during the 2011-12 school year — the most recent statistics available — only 17.7 % of the nation's public middle, high and combined schools met the 8:30 a.m. guideline, and nearly 40% started before 8 a.m. In California, the average start time was 8:07 a.m.
Many districts are reluctant to change their schedules because they see the shift as too expensive and disruptive. But that's short-sighted. In the long run, a later start could actually save schools money — and benefit society at large.
Later start times can mean less missed school — absences dropped 15% in Bonneville County, Idaho, after it instituted such a change, according to a 2014 Children's National Medical Center report. In states such as California where state funding for schools is tied to attendance, it follows that later start times could translate into extra dollars. Megan Reilly, chief financial officer for the Los Angeles Unified School District, has estimated that boosting attendance by just 1% districtwide would bring in an additional $40 million per year.
Repeated studies also show that when the school day starts later and teens get more sleep, both grades and standardized test scores go up. A Colby College economist, Finley Edwards, found that a one-hour delay in start time increased math test and reading test scores by three percentile points. Even more striking, the lowest-scoring students showed the biggest jumps.
Compared to other strategies for boosting performance, delaying the start of the school day is easy and efficient. Teny M. Shapiro, an economist at Santa Clara University, estimates that a one-hour change produces the same benefit as shrinking class size by one-third or replacing a teacher in the 50th percentile of effectiveness with one in the 84th percentile.
Another potential problem schools commonly raise is that later start times would lead to kids missing classes at the end of the day in order to attend sporting events, or that athletic participation rates would decline. There may be something to these concerns; but on the other hand, there's reason to believe more sleep would result in fewer student injuries — and, in turn, fewer missed hours in class and on the field.
Student athletes who get enough sleep are far less likely to get injured. In a 2012 study of Los Angeles middle- and high-school athletes, researchers found that getting less than eight hours of sleep was the strongest predictor of injury. Two-thirds of the athletes who didn't meet this threshold got injured.
Another study, in North Carolina, showed that more than a quarter of injured high-school athletes missed at least one week of playing time. While less than 20% of the injuries required emergency room treatment, according to the North Carolina study, the costs were still significant: the researchers found that even the minor injuries added up to nearly $1 million a year in medical costs.
But sleepy teens aren't just a problem in school. When they get behind the wheel, they contribute to what the National Highway Traffic Safety Administration calls the "extreme danger" of drowsy driving, which has an estimated annual societal cost of $109 billion. "Teens and young adults are involved in more than half of all drowsy driving crashes annually," notes Jonathan Adkins, executive director of the Governors Highway Safety Assn. Beyond the obvious safety concerns, there's a corresponding hike in car insurance premiums, with a 2013 study by InsuranceQuotes.com finding that Californians' rates jump an average of 62% after just one claim.
Again, later school start times have been shown to improve the situation. In Lexington, Ky., teen car crashes for 17- and 18-year-olds dropped 16.5% in the two years following a start-time shift; during the same period, the accident rate for this age group increased 7.8% elsewhere in the state.
As if all of this weren't enough, teens who don't get enough sleep are more at risk for drug and alcohol use, depression and suicide. The title of a 2014 report in the Journal of Youth and Adolescence says it all: "Sleepless in Fairfax: The Difference One More Hour of Sleep Can Make for Teen Hopelessness, Suicidal Ideation, and Substance Use."
In the first half of the 20th century, school started later. Districts implemented early starts for efficiency and cost-cutting reasons; tiered bus systems, for instance, led to staggered start times for elementary, middle and high schools — with high schools starting first. At the time, the risks of teen sleep deprivation were not widely known. Schools don't have that excuse anymore.
If schools go ahead and shift their start times, they may have to change bus schedules or alter team practice schedules. But that's nothing in comparison to what they'd gain.