Teen sleep and the body clock

Many parents think their teen is just lazy or glued to a phone when they cannot fall asleep before midnight and cannot wake up for school. Part of the story is biology. During puberty, the body clock shifts later, so a teen may not feel sleepy until late at night. Then early school start times cut the night short.

Sleep is not a luxury for teens. It shapes mood, focus, learning and safety. This guide explains what is going on, how much sleep teens need, and what teens and families can do.

How much sleep teens get

The American Academy of Sleep Medicine recommends 8 to 10 hours a night for ages 13 to 18.¹ Most teens fall short.

In CDC's 2025 survey, 24% of U.S. high school students slept at least 8 hours on an average school night.¹ That was about the same as 2023 but lower than in 2015.^1,6 Sleep gets shorter as teens move through high school:¹

Girls (22%) were a little less likely than boys (26%) to get enough sleep.¹

Signs a teen isn't getting enough sleep

• Very hard to wake up on school days, or sleeping far longer on weekends
• Falling asleep in class, on the bus, or while doing homework
• Irritability, low mood, or crying easily
• Trouble concentrating, remembering or staying motivated
• Needing caffeine to get through the day
• Drowsiness while driving

Teens often sleep in on weekends to catch up, sometimes up to about 2 extra hours a night.⁴ A big gap between weekday and weekend sleep is a sign of ongoing sleep loss.

The insomnia test and our sleep diary can help you see your own pattern.

Why teens struggle to sleep

The body clock shifts later. Around puberty, teens start to prefer later bedtimes and later mornings.⁴ One reason is that melatonin, the hormone that helps signal sleep, is released later in the 24-hour day in teens. That makes going to bed and waking up later feel natural.³

Sleep pressure builds more slowly. The drive to sleep that builds up during the day seems to grow more slowly in older teens, which can make it easier to stay up late.⁴

Early school start times. When school starts early, teens have to wake up before their body clock is ready. The American Academy of Pediatrics (AAP) recommends middle and high schools start no earlier than 8:30 a.m.²

Busy lives. Homework, sports, jobs and social life push bedtime later, and parents tend to check bedtimes less as teens get older.⁴

Screens and light. Bright light late in the evening can make it harder to fall asleep.³ Using screens late is linked to later bedtimes and less sleep.² About 45% of U.S. teens say social media hurts their sleep, including half of girls.⁷ See social media and teens.

Stress and worry. Racing thoughts about school, friends or family can keep teens awake. See school and exam stress.

Want to know your natural rhythm? Try the morning person or night owl quiz.

How sleep affects mental health and safety

Sleep and mood work in both directions. Poor sleep makes it harder to manage emotions, and anxiety or depression can make it harder to sleep. Read more in sleep, mood and anxiety.

In CDC's 2023 survey, students who slept at least 8 hours on school nights had about 33% to 47% lower rates of persistent sadness, poor mental health, seriously considering suicide and attempting suicide.⁵ These are links, not proof that sleep alone causes the difference, but they are strong.

Too little sleep also raises the risk of poor mental health, attention and behavior problems, lower grades, injuries, obesity and type 2 diabetes.² It can increase risky behavior, especially unsafe driving.¹ In one Kentucky school district that moved start times later, teen car crashes fell by about 16.5% while they rose elsewhere in the state.⁴

What helps

A 2-week sleep reset

1. Pick a wake time you can keep every day, including weekends. Allow no more than about an hour of sleeping in.
2. Count back 8 to 9 hours to find your target bedtime. If that feels impossible, move your bedtime 15 minutes earlier every few nights.
3. Set a screen curfew. Put your phone and laptop away at least an hour before bed, and charge your phone outside your room.¹
4. Dim the lights in the last hour. Read, stretch, shower or listen to calm music. Try a body scan or muscle relaxation.
5. Watch caffeine. Energy drinks, coffee and some sodas contain caffeine. Limit caffeine, especially after lunch.¹⁰
6. If you can't sleep after about 20 minutes, get up and do something quiet in dim light, then go back to bed when sleepy. This is one of the skills taught in CBT-I.
7. Track it. Use our sleep diary for two weeks to see what helps.

For parents and caregivers

• Set a bedtime together. Teens whose parents set bedtimes tend to sleep more.¹ Make it a family agreement, not a punishment.
• Keep devices out of bedrooms at night, including yours, if you can. Charging stations in the kitchen help.^1,2
• Look at the total load. Late practices, jobs and heavy homework can make 8 hours impossible. Help your teen choose.
• Don't take it personally if your teen is grumpy in the morning. Their body clock is working against them.
• Watch for sleep problems that need a doctor, such as loud snoring, gasping in sleep, or daytime sleepiness despite enough time in bed.
• Talk with your child's doctor before trying sleep aids, including over-the-counter products.
• Speak up for later school start times. CDC suggests schools look at how start times affect sleep and work with families on later starts.¹

See our guide for parents.

Special situations

Teens who drive. Drowsy driving is a serious risk.¹ A teen who has slept poorly should not drive, especially early in the morning or late at night.

Teens with anxiety, depression or ADHD. Sleep and mood affect each other, so poor sleep can make symptoms harder to manage. Tell the doctor about sleep problems as well as mood or focus. See anxiety and depression in teens.

Athletes and teens with jobs. Early practices and late shifts can squeeze sleep from both ends. A short nap can take the edge off, but it does not replace a full night.

Teens who share a room or live in noisy homes. Earplugs, an eye mask and a simple wind-down routine can help when the space cannot change.

Common questions

Can teens catch up on sleep on weekends?

Sleeping in a little can help repay some lost sleep, and teens often sleep up to about 2 hours longer on weekends.⁴ But big swings shift the body clock later and make Monday mornings harder. A steady wake time works better.

Is it bad to use my phone in bed?

Using screens late is linked to later bedtimes and less sleep, partly because of bright light.^2,3 Charging your phone outside your room is one of the simplest changes you can make.¹

Should my teen take melatonin?

Talk with your child's doctor first. Sleep habits and, for ongoing insomnia, CBT-I are the usual first steps.⁹

How long before bed should I stop studying?

Try to finish at least 30 to 60 minutes before bed and use that time to wind down. If homework regularly runs late, talk to a teacher or counselor about your workload.

When to get help

See a doctor if a teen:

• Has trouble falling or staying asleep most nights for several weeks
• Is very sleepy in the daytime even after enough time in bed
• Snores loudly, gasps or stops breathing during sleep
• Has sleep problems along with low mood, worry or loss of interest

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.