NOTE: The American Academy of Pediatrics has recommended school start times no earlier than 8:30 for teens. Read more here.
A few years ago, I had a sixteen year old come into sleep clinic for insomnia. He was a hard-working student in a good school district. I asked him to describe his sleep problems to me. “I finish my homework at midnight every night,” he said, “and I can’t fall asleep by 12:10 AM.” Each of his Advanced Placement classes had 1-2 hours of assigned homework per night and he was not routinely finishing homework until 11 PM or 12 AM. This may be an exaggerated case [and note that the details have been changed a bit to protect patient privacy.] However, let’s do the math. The typical school day for a high school student in this country is between 6.5-7 hours per day. Most school districts start between 7-8 AM for high school students. Thus, kids are getting out of school between 2-3 PM. Many students do extracurriculars for a few hours after school and cannot start homework until after dinner (say 6:30 PM). The maximum recommended homework for a high school senior is three hours per night; for younger children, it is ten minutes per grade. If the student goes to sleep at 10 PM and gets up at 6 AM ( a typical wake time around here for high school students), this allows 8 hours of sleep. However, the typical teenager requires between 8.5-9 hours of sleep per night, so even a teen with good sleep habits generally sleep deprived. In Boston, this problem is frequently exaggerated by school choice where some children are assigned to better schools which are a long bus ride away. (These issues exist elsewhere. My friend Trapper Markelz grew up in Alaska and regularly took 45 minute bus trips twice a day to school.)
In their recent article, “To Study or to Sleep? The Academic Costs of Extra Studying at the Expense of Sleep“, Cari Gillen-O’Neel and colleagues studied the effects of staying up late on students. They studied 535 kids through high school. The average sleep time for these teens diminished from 7.6 to 6.9 hours of sleep from 9th to 12th grade. When they examined what happened when teens stayed up late to study for finish a project, they found that
Results suggest that regardless of how much a student generally studies each day, if that student sacrifices sleep time to study more than usual, he or she will have more trouble understanding material taught in class and be more likely to struggle on an assignment or test the following day.
Essentially, staying up late to cram tends not to help and actually worsens performance. This emphasizes the importance of encouraging good study habits in kids.
Excessive homework is not the only factor squeezing teenager’s sleep. My friend Lauren Daisley had a great video on CBS Sunday Morning several weeks ago discussing early school start times. Sleepiness in teenagers is a major public health issue and early school start times contribute to this. To highlight some recent research:
- Short sleep makes children obese.
- A recent study showed that teenagers who did not get enough sleep were more likely to develop insulin resistance, which is the precursor to type 2 diabetes.
- Sleepiness is a significant cause of automobile accidents which is the most common cause of death in teenagers.
- Depression, anxiety, and irritability are all associated with insufficient sleep.
There is a significant body of research showing the benefits of moving school start times later. Demonstrated benefits have included less tardiness and absenteeism, lower levels of depression, and, most significantly, lower levels of car accidents in teenagers. (There are several great summaries here from the National Sleep Foundation, the New York Times, the Wall Street Journal, and Psychology Today.)
I also think that there are more abstract benefits to avoiding overscheduling for children and teens. In William Deresiewicz’s 2009 essay, “Solitude and Leadership,” he writes about his experience as an admission officer at Yale (full disclosure: my alma mater.) He writes,
Well, it turned out that a student who had six or seven extracurriculars was already in trouble. Because the students who got in—in addition to perfect grades and top scores—usually had 10 or 12.
So what I saw around me were great kids who had been trained to be world-class hoop jumpers. Any goal you set them, they could achieve. Any test you gave them, they could pass with flying colors. They were, as one of them put it herself, “excellent sheep.”
He argues, however, that for real leadership and problem solvers, you need people who can think and innovate. And that solitude and time for reflection is critical for developing this faculty. Allowing teens extra time may not even hurt their college admission chances. I really enjoy the blog Study Hacks by Cal Newport, a computer science professor who been writing since he was a grad student. He wrote a great article (and a book as well) on how working against the conventional wisdom (e.g. doing a few extracurriculars instead of 10-12) can be a winning strategy for a motivated high school student. I highly recommend reading this: Want to Get into Harvard? Spend More Time Staring at the Clouds: Rethinking the Role of Extracurricular Activities in College Admissions.
Obviously, teenagers are not blameless. Screen time and social media shares some of the blame. But I am most concerned about these structural issues which do not allow enough of a sleep opportunity for kids. These issues are determined at the level of the school district. However, there are some actions that parents can take:
- The US is a relatively homework intense country compared to other industrialized countries with higher standardized test scores. Whether your child is in third grade or twelfth, keep an eye on the amount of homework they are receiving. The rule of thumb is ten minutes/grade level. Have a frank discussion with your child’s teachers or principal if it seems excessive. Be aware that excessive homework times can also reflect difficulties like attention deficit hyperactivity disorder or learning disabilities.
- School start times are typically addressed at the town or district level. As you can imagine, this is a difficult issue to move at the national or state level. If you are concerned by the school start times in your district, go to school board meetings. Also, get involved with Start School Later, an organization dedicating to addressing this issue.
- Make sure that your child has an age appropriate bedtime allowing for enough sleep (10-11 hours in elementary school, 9-10 hours middle school, 9 hours high school). Limit screen time in the evenings before bedtime.
- Prolonged napping can result in significant difficulty at bedtime.
- Keeping screens out of the bedroom except when absolutely necessary can help avoid sleep problems in kids and teens.
- Going on a “light diet” to limit night time light exposure is important for limiting the impact of late night homework sessions on overall sleep patterns.
It is also important to understand the biology of when you fall asleep. This is comprised of a two part system: a) the homeostatic sleep drive (the longer you are awake, the quicker you fall asleep) and b) the circadian or body clock system which helps keep you awake in the evenings.
For more on the topic of homework vs sleep, here is an article I just wrote on the controversy about the value of homework.