Sleep through life
Teens, Sleep and School Start Times
Teenagers need 8 to 10 hours of sleep, but puberty shifts their body clocks later just as early school days begin. We explain the biology, the case for later school start times and what families can do.
Teens need more sleep than adults
The AASM recommends 8 to 10 hours of sleep per night for teens aged 13 to 18. Most US high school students get less than 8 hours on school nights, according to CDC survey data. Insufficient sleep in teens is linked to poorer academic performance, mood problems, risk-taking, sports injuries and drowsy driving crashes.
The biology of the late teen body clock
During puberty, the timing of melatonin release shifts later, and sleep pressure builds more slowly during the day. Many teens genuinely cannot fall asleep until 11pm or later. This is a biological change, not just a lack of discipline. Evening screen use, homework and social activity can push it even later.
Why school start times matter
In 2014 the American Academy of Pediatrics recommended that middle and high schools start no earlier than 8:30am. The AASM issued a 2017 position statement agreeing that middle and high schools should start at 8:30am or later. Studies of schools that delayed start times have found that students got more sleep, with improvements in attendance, alertness and in some studies fewer car crashes among teen drivers. California became the first US state to set a statewide minimum: since 2022, most public high schools must start no earlier than 8:30am and middle schools no earlier than 8:00am.
What families can do
- Protect a consistent wake time, and keep weekend sleep-ins to within about 1 to 2 hours of school days.
- Get bright light in the morning: breakfast by a window or walking to school.
- Agree on a device curfew and charge phones outside the bedroom overnight.
- Limit caffeine and energy drinks, especially after lunch.
- Plan homework and activities to leave time for 8 or more hours of sleep.
- If needed, an early afternoon nap of no more than 20 to 30 minutes can help, but long late naps make bedtime harder.
Drowsy driving
New drivers who are sleep deprived are at higher crash risk. Teens should not drive when drowsy, especially early in the morning or late at night. Families can set rules that a sleepy teen calls for a ride instead.
When to seek help
Talk to a doctor if your teen is persistently sleepy despite adequate sleep time, falls asleep in class, snores loudly, has very late sleep timing that does not respond to good habits (possibly delayed sleep-wake phase disorder), or shows signs of depression or anxiety.
Frequently asked questions
Why can my teenager not fall asleep early?
Puberty shifts the body clock later. Teens often cannot feel sleepy until around 11pm or later, which is why early school start times cause chronic sleep loss.
How much sleep does a teenager need?
The AASM recommends 8 to 10 hours per night for teens aged 13 to 18.
Should teens sleep in on weekends?
A little extra sleep helps, but sleeping in much more than an hour or two can shift their body clock later and make Monday mornings harder.
Sources
This page is general information, not a diagnosis or medical advice. Read our medical disclaimer.