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According to a survey by the National Sleep Foundation, 60% of teenagers report feeling tired during the day, and 15% have fallen asleep at school.
Sleep-deprived kids are more likely to suffer academically, be overweight, display symptoms of depression, and engage in risky behaviors like drinking, smoking, and using drugs.
Clearly, poor sleep is bad for students. Fortunately, the American Academy of Sleep Medicine, the American Academy of Pediatrics, and a wide host of academic researchers, parents, and other advocacy groups have identified a potential fix: changing school start times to 8:30 am or later.
Unfortunately, 93% of high schools and 83% of middle schools start before 8:30am, according to the CDC.
Could later school start times be the solution for healthier, happier students? An ever-growing body of research says yes.
Below we review the dangers of sleep deprivation for students, and why the unique sleep needs of adolescents are a key consideration in delaying school start times. Then we take a look at the major studies supporting a change in school start times.
Given that 90% of students don’t get their recommended 9 hours of sleep on school nights, it’s no wonder students are so exhausted.
With increasing responsibilities from work, school, and extracurriculars, students simply don’t have time for sleep. Making matters worse, many adolescents and parents are unaware of how certain behaviors they engage in, such as using electronics at night, actually reduce the quality of the sleep they do get.
Sleep deprivation isn’t something to take casually. It’s serious for all of us, and more so for teenagers.
Whenever we’re sleep deprived, even it’s just from one night of poor sleep, our cognitive functioning suffers. That includes our ability to concentrate, our ability to retain or remember information, and our ability to problem-solve. These skills are all required to perform well academically.
Sleep deprivation affects us emotionally, too. Sleep-deprived people are more likely to make poor judgments, act irrationally, or have difficulty regulating their mood or impulses. For teenagers whose hormones are already going haywire, these effects are only worsened. It can cause them to engage in substance abuse, have trouble coping with the stress of school and social life, and think they’re okay to drive when they’re really too tired. Car accidents are the leading cause of death for teens.
Finally, sleep deprivation has physical consequences, too. When we don’t get enough sleep, our body produces more of the ghrelin hormone, which craves sugary and fatty foods, and less of leptin, our appetite-regulating hormone. Sleep deprivation can lead to weight gain, or simply fueling yourself with the wrong kind of food – making you even more tired. Chronic sleep deprivation is also a risk factor for type 2 diabetes, heart disease, and certain types of cancer.
Sleep deprivation can negatively impact teens – mentally, emotionally, and physically. But do school start times really have such a large effect on adolescents, and if so, why? Next we’ll review the unique sleep pressures placed on adolescents, as well as the research-backed benefits to enforcing later school start times.
One large reason students are so sleep-deprived is that they need more sleep than the rest of us, but they have no time to get it. Teenagers actually need 9 hours of sleep per night, as opposed to the 7 to 8 hours recommended for adults.
Also, right around adolescence, children experience a natural circadian shift, where their body and mind become tired at a later time of day than when they were younger. Their brain begins melatonin production (the sleep hormone) later in the evening, and stops production later in the morning. As a result, they naturally feel ready to fall asleep and wake up later. Unfortunately, this corresponds with the time they often start going to school earlier.
School start times are a big deal because in large part, they dictate the way adolescents live their lives. Start times are non-negotiable and unyielding. As such, students have to find ways to fit in everything else they’re responsible for outside of school.
That includes homework, extracurricular activities, family obligations, jobs, hobbies or leisure time with friends, and basic needs like eating and bathing. These demands have only increased as colleges and career opportunities become more competitive.
I sat in the living room in our house on the ground, crying and having horrible breathing problems. It was so scary. I think it was from the accumulated stress, the fear over my grades, the lack of sleep and the crushing sense of responsibility. High school is a very hard place to be."
- Chloe Mauvais, sleep-deprived high school senior
Complicating matters is the poor sleep hygiene many adolescents unknowingly practice. Sleep hygiene refers to the thoughts, behaviors, and habits we have around sleep (similar to how your oral hygiene affects your dental health).
Among other things, the basics of good sleep hygiene include:
As any parent of an adolescent can attest, many teenagers do not adhere to these ideals, and often through no fault of their own. They drink a lot of caffeine or energy drinks in order to keep up with their responsibilities, trying to avoid exhaustion from running on such low sleep. They sleep in on the weekends, causing a sleep hangover effect come Monday morning. After hours of homework, they finally go to bed with their smartphones, where the blue light from the device tricks their brain into thinking it’s daytime and keeps them awake.
It’s nice to stay up and talk to your friends or watch a funny YouTube video. There are plenty of online distractions."
- Carolyn Walworth, sleep-deprived high school senior
Many of our habits continue into adulthood, where these same poor sleep hygiene practices continue to cause problems. Many of us are simply unaware about good hygiene. But even if they do know how to practice good sleep hygiene, many teens are forced to forego it in order to cram for a test or fit in their extracurriculars.
Overwhelmingly, the current body of research suggests that later school start times are better for adolescents.
Generally, it follows that with later school start times, students spend that extra time sleeping, and wake up later in the mornings. As a result, they get more sleep, resulting in significant benefits to their overall well-being. Most studies have found that delaying start times by just 30 minutes can make a huge difference.
Unfortunately, and perhaps surprising given the persuasive list of benefits above, many parents are actually opposed to later start times. It would impact their daily routines, and they don’t understand how critical sleep is to their child’s health and academic performance. According to a University of Michigan survey, just 51% of parents support later school start times.
We found that parents underestimated how much sleep their children needed, and only about half agreed with existing recommendations that school start times should be later. [But] there's evidence that it's a win-win for everyone. We cannot change teens' biology to have them sleep earlier, so we should push the school start times back, in line with recommendations from the American Academy of Sleep Medicine and the American Academy of Pediatrics."
- Galit Dunietz, PhD
Below you’ll find our review of the current literature surrounding school start times, adolescent sleep, and academic performance. Studies are organized chronologically, from most to least recent.
Nearly 1,000 junior high students (7th and 8th graders) from 11 schools participated in this Children’s National Health System study, divided between those attending schools with average 8am start times and those with 7:23am start times. Both parents and students filled out online surveys during the study.
Going to sleep earlier to allow for earlier start times is not possible for many teens as their biological clocks are delayed, at least relative to younger children and adults. We know that when we do not go to bed and wake at optimal times there are increased risks for physical and mental health problems."
- study author Daniel S. Lewin, PhD
This study looked at 375 students at an all-girls’ high school in Singapore. The researchers worked with the school to delay their start times by 45 minutes, in order to evaluate the impact on the students on a short-term and long-term basis.
The researchers were also particularly interested in how the later school start time would affect students’ behaviors and societal acceptance, given the large focus on academic success in East Asian countries.
Starting school later in East Asia is feasible and can have sustained benefits. Our work extends the empirical evidence collected by colleagues in the West and argues strongly for disruption in practice and attitudes surrounding sleep and wellbeing in societies where these are believed to hinder rather than enhance societal advancement."
- lead researcher, Michael Chee, MBBS
Over 400 high school students from twenty American cities completed daily sleep diaries to provide data for this study.
The presumption is if you let kids start school later they will simply go to sleep later and still not get enough sleep. But that’s a hypothetical scenario. There wasn’t data to back that up."
- researcher Orfeu M. Buxton, PhD
This large-scale study included over 35,000 high school students from 78 schools in Ontario and Alberta, Canada. Controlling for race/ethnicity, school area, median household income, and sex, the researchers analyzed whether the students’ reported sleep duration was affected by their school start times.
Over 30,000 students from 29 public high schools participated in this study to determine the effect of later school start times on graduation and attendance rates. The study compared graduation and attendance rates before and after delaying the school start times.
Researchers collected data from nearly 200 students nationwide between the ages of 14 and 17. Students completed surveys about their basic sleep hygiene, circadian chronotype (“night owl” or “early bird”), and school start times. Students were then separated into two groups, based on whether they started before or after 8:30 am (as recommended by the AAP). Students kept a sleep diary for 7 days, marking their sleep hygiene behaviors, assessing their sleep quality and duration, and whether they experienced any symptoms of depression or anxiety.
[O]urs is the first to really look at how school start times affect sleep quality, even when a teen is doing everything else right to get a good night’s sleep. While there are other variables that need to be explored, our findings show that earlier school start times seem to put more pressure on the sleep process and increase mental health symptoms, while later school start times appear to be a strong protective factor for teens."
- lead researcher Jack Peltz, PhD
A large reason why schools have not suddenly changed their start times in response to all this research is an obvious one: cost. It costs money to make sweeping changes like these, with a large part of that cost coming from the changes to bus schedules. Currently bus schedules are staggered by high school and elementary start times, so more busses and drivers would need to be employed in order to transport all students at the same time.
This study was unique because as opposed to looking at the sleep health impacts of school start times, RAND analyzed the economic impacts. Study authors used benefit-cost projections of 47 states to see the effects on the U.S. economy and public health. The authors concluded that delaying school start times to 8:30 am would not only improve public health, but also the economy, and do both in a cost-effective manner.
Researchers collected school start times from 362 schools across Canada, and data from nearly 30,000 students aged 10-18. The average start time was 8:43 am.
Researchers followed over 9,000 high school students from 8 public schools to compare academic performance and health outcomes for students at schools with earlier vs. later start times.
Another issue is that kids who are sleep deprived tend to be snackers and more sedentary. Sleep is tied to healthy eating and exercise."
- lead researcher Kyla L. Wahlstrom, PhD
A study of nearly 10,000 students from a single school district analyzed the effect of a 1-hour delayed start time on student sleep duration and car accidents. Start times were delayed from 7:30am and 8:00am for high school and middle schools, respectively, to 8:30am and 9:00am.
Over 200 middle school students participated in this study, who all attended urban public schools that started at 7:15am or 8:37am. To avoid other variables interfering with the results, the students selected for the study shared similar bedtimes, sleep hygiene practices, and weekend sleep schedules.
A small sample of about 30 student participants were evaluated as they transitioned from 9th grade in junior high to 10th grade at high school. They went from a school that started at 8:25 to one at 7:20am. Students kept sleep diaries, while researchers recorded additional data through actigraphy, lab evaluations, and multiple sleep latency tests (MSLT).
As one of the initial studies on adolescent sleep and school start times, this study was important in charting the change a new school start time had on sleep patterns – in isolation of other changes.
Even without the pressure of biological changes, if we combine an early school starting time--say 7:30 am, which, with a modest commute, makes 6:15 am a viable rising time--with our knowledge that optimal sleep need is 9 1/4 hours, we are asking that 16-year olds go to bed at 9 pm. Rare is a teenager that will keep such a schedule. School work, sports practices, clubs, volunteer work, and paid employment take precedence. When biological changes are factored in, the ability even to have merely 'adequate' sleep is lost."
- lead researcher Mary A. Carskadon, PhD