How Much Sleep Do Teenagers Need? (And Why They Can’t Fall Asleep Early)
Teenagers aged 13 to 18 need 8 to 10 hours of sleep a night, according to the American Academy of Sleep Medicine. Most don’t get it: in CDC survey data for 2021, between 71% and 84% of high school students, depending on the state, slept less than 8 hours on school nights. Part of the reason is biological. During puberty, the body clock shifts later, so teens naturally feel sleepy later at night.
Key facts
- Teens need 8 to 10 hours of sleep, according to the AASM.
- In 2021, 71% to 84% of US high school students slept less than 8 hours on school nights, depending on the state.
- Puberty delays the release of melatonin, so many teens can’t fall asleep until about 11 PM or later.
- The American Academy of Pediatrics recommends middle and high schools start no earlier than 8:30 AM.
Why teenagers stay up late
It’s not just phones and homework. Research led by Mary Carskadon at Brown University found that during puberty, the body starts releasing melatonin, the hormone that signals night-time, later in the evening. Teens’ body clocks can keep them awake about two hours later than younger children’s. At the same time, the pressure to sleep builds up more slowly during the day, so teens can stay awake longer.
The result: a 16-year-old may not feel sleepy until 11 PM or later, but still has to get up at 6:30 AM for school. That’s at most 7.5 hours, below the minimum they need.
How many teens are short of sleep?
| Group (US high school students, 2021) | Slept less than 8 hours on school nights |
|---|---|
| Lowest state (South Dakota) | 71% |
| Highest state (Pennsylvania) | 84% |
| Female students | 80% |
| 12th graders | 84% |
Source: CDC, Youth Risk Behavior Survey, 2021. The CDC reports that the share of students not getting enough sleep increased between 2009 and 2021.
School start times
In 2014, the American Academy of Pediatrics recommended that middle and high schools start no earlier than 8:30 AM, so teenagers can get 8.5 to 9.5 hours of sleep. At the time, the CDC found that only 17.7% of US public middle and high schools started at 8:30 or later, and the average start time was 8:03 AM. California has since passed a law requiring most high schools to start no earlier than 8:30 AM, and other states and school districts have debated similar changes.
Bedtimes for teenagers
To get 8 to 9 hours, a teenager needs a bedtime of about:
| Wake-up time | Bedtime for 8 hours | Bedtime for 9 hours |
|---|---|---|
| 6:00 AM | 9:45 PM | 8:45 PM |
| 6:30 AM | 10:15 PM | 9:15 PM |
| 7:00 AM | 10:45 PM | 9:45 PM |
| 7:30 AM | 11:15 PM | 10:15 PM |
Including 15 minutes to fall asleep. Use the sleep calculator with the age set to 13–18 years for times that line up with sleep cycles.
What helps
- Keep wake-up times steady. Sleeping in until noon at the weekend shifts the body clock even later, making Monday harder. Try to keep weekend wake-up times within about 2 hours of weekdays.
- Get morning light. Bright light soon after waking helps move the body clock earlier.
- Dim the evenings. Bright screens and lights late at night push the body clock later. The AASM suggests turning off electronic devices at least 30 minutes before bed.
- Watch the caffeine. Energy drinks and coffee after school can keep teens awake late. See the caffeine cut-off calculator.
- Protect sleep before tests and games. Sleep helps memory and reaction time, so an all-nighter usually backfires.
Sources
- Paruthi S et al. Recommended amount of sleep for pediatric populations. AASM, 2016
- CDC: FastStats: sleep in high school students
- CDC MMWR: School start times for middle school and high school students, 2011–12
- Psychiatric News: Teens’ body clocks and school start times
Frequently asked questions
Is 7 hours of sleep enough for a teenager?
No. Teens need 8 to 10 hours. Regularly getting 7 hours means building up sleep debt.
Why is my teenager so tired in the morning?
Their body clock is shifted later, so an early alarm wakes them during their biological night.
What time should a 15-year-old go to bed?
Around 9:30 to 10:30 PM for a 6:30 to 7 AM wake-up, to get at least 8 hours.
