Sleep by age
How much sleep does a teenager need?
Teenagers aged thirteen to eighteen need 8 to 10 hours a night. Almost none of them get it, and the reason is not laziness or phones. It is that the body clock shifts later in adolescence and the school day does not.
In short
The American Academy of Sleep Medicine recommends that teenagers aged 13 to 18 years sleep 8 to 10 hours per 24 hours on a regular basis. The obstacle is a genuine biological shift: the adolescent circadian rhythm runs later, so a teenager cannot reliably fall asleep at the time an early school start requires.
- Hours per night
- 8 to 10Hours per nightAASM, ages 13 to 18
- Lights out for a 6:30 alarm
- 9 pmLights out for a 6:30 alarmAt the low end of the range
- Weekday to weekend swing
- 2 hWeekday to weekend swingThe gap has a name: social jetlag
Teenagers, 13 to 18 years
8 to 10hours per night
As published by the American Academy of Sleep Medicine in its consensus statement on recommended sleep duration. Quoted as a range because that is how it was issued: healthy sleepers in this band sit across the whole span, and a single number would be us inventing a precision the evidence does not have.
The clock moves later and the school day does not
The delay in adolescent sleep timing is one of the better established findings in the field, and it is worth being precise about what it means. It is not that teenagers prefer late nights. It is that the biological signal to sleep arrives later than it did in childhood, so a fifteen year old told to be asleep at nine is being asked to sleep during a period when their own physiology is still producing wake drive.
Put that against a school day starting at half eight and the arithmetic collapses. If sleep is not available until eleven and the alarm is at half six, the maximum achievable is seven and a half hours against a recommendation of eight to ten, before anything goes wrong.
Weekend catch-up is a time zone, not a fix
The predictable response is to sleep until noon on Saturday, which does recover some of the debt and simultaneously pushes the body clock further back. Monday morning is then worse than the previous Monday, and the cycle tightens.
The name for that gap between the schedule your body wants and the one your week imposes is social jetlag, and it is measurable rather than metaphorical. The mechanism is at /glossary/social-jetlag. The practical compromise is a smaller swing, an hour or so rather than three, with the wake time moving less than the bedtime.
What actually moves the needle
Two things have real leverage here and neither is a lecture about screens. Bright light soon after waking pulls the clock earlier, and it does more than any evening intervention. Dim light in the last ninety minutes before bed stops pushing it later, and that is where screens matter, though brightness and timing matter more than the device.
The third thing is consistency, which is unglamorous and effective. Holding the wake time within an hour across all seven days does more for a teenager than any amount of effort spent on the bedtime, because the morning is what sets the clock.
The full method is at /guides/how-to-fix-your-sleep-schedule, and the persona page for a late body clock at /for/night-owls.
What is actually different at this age
The total is the headline. These are the things that change underneath it, and they are usually what somebody is really asking about.
What changes
- The circadian rhythm shifts later through adolescence, so the same teenager who fell asleep at nine at eleven years old genuinely cannot at fifteen.
- School start times were not designed around that shift, which turns an ordinary alarm into a permanent early one.
- The weekend catch-up that follows is a two or three hour swing, and the body clock reads it as travel.
Where an app stops being the right tool
Stated plainly rather than buried, because a sleep app writing about sleep has an obvious incentive not to.
Limits worth knowing
- Tock requires a subscription and is not a free tool for a student to install without thinking about it. The roundup at /best/best-sleep-apps-for-students puts the free options first, and means it.
- No app fixes a school start time, which is the actual constraint on this page.
- Persistent difficulty sleeping, or daytime sleepiness that does not respond to a longer night, belongs with a doctor rather than an app.
Tock estimates sleep and is not a medical device. Nothing here is medical advice, a diagnosis, or a substitute for one. If sleep is genuinely not working, that is a conversation for a doctor rather than for an app or an article.
Questions people ask
How much sleep does a 16 year old need?
The American Academy of Sleep Medicine recommends 8 to 10 hours per night for teenagers aged 13 to 18. With a 6:30am alarm, the low end of that range means being asleep by about half past ten, which is genuinely hard for an adolescent body clock.
Why cannot my teenager fall asleep early?
Because the circadian rhythm shifts later during adolescence. The signal to sleep genuinely arrives later than it did in childhood, so being told to sleep at nine means lying awake rather than sleeping. It is physiology rather than preference, and it reverses in early adulthood.
Is 6 hours of sleep enough for a teenager?
No. It is well below the recommended 8 to 10 hours, and the gap is larger for teenagers than the same shortfall would be for an adult, because the requirement is higher. Six hours as a weekday pattern is a substantial and accumulating deficit.
Does sleeping in at the weekend help?
It recovers some of the debt and it pushes the body clock later, which makes the following Monday harder. A smaller swing works better: an hour later at the weekend rather than three, with the wake time moving less than the bedtime.
Other age bands
The same consensus statement, read for a different age.
- How much sleep school-age children needThe American Academy of Sleep Medicine recommends that children aged 6 to 12 years sleep 9 to 12 hours per 24 hours on a regular basis. By this age sleep has consolidated into the night, so the figure is effectively a nightly one and the bedtime has to be counted backwards from the school run.
- How much sleep adults needThe American Academy of Sleep Medicine recommends that adults sleep 7 or more hours per night on a regular basis to promote optimal health. It is expressed as a minimum rather than a range because the evidence supports a lower bound far more firmly than it supports an ideal figure.
Elsewhere on the site
A different corner of the same problem.
- NapsThe 60 minute napA 60 minute nap includes a substantial amount of slow wave sleep, which is useful for recovery and for some kinds of memory, and it usually ends before the cycle completes. That means the benefit is real and the wake-up is often groggy, so it suits situations where the hour afterwards is flexible.
- Wake tonesSunrise alarmA sunrise alarm clock is a bedside lamp that brightens over roughly 20 to 30 minutes before your set time, and the light is the part you are paying for. Tock is an iPhone app with no light hardware at all, so it takes the timing half instead: a soft wake tone rung at a lighter moment inside the last 30 minutes rather than at a fixed time.
- Head to headAutoSleep vs PillowAutoSleep suits the person who wants every number and no recurring bill. Pillow suits the person who wants the night caught automatically and presented calmly, then written properly into Apple Health.
- FeaturesSnore recordingTock keeps short audio clips of the things it hears in the night and pins each one to the minute it happened. Snoring, coughing and sleep talking are labelled by name, and every clip has a play button in the morning.
- Sleep soundsLate cafeA cafe bed works because a room with people in it reads as safe, and it only keeps working while none of the voices are intelligible. The moment you can pick out a word you start following it, and following language is the opposite of falling asleep, which is why Tock generates the murmur instead of recording a real room.
- Tock for youNight owlsYou are wide awake at 1am and useless at 7am, and every piece of advice you have ever read starts with going to bed earlier, which you have done, repeatedly, while staring at the ceiling.
Knowing the number is the easy half
Hitting it is the other one. Tock measures what you actually got rather than what the schedule allowed for, and wakes you at a lighter moment inside the last half hour.