Most adults need 7–9 hours of sleep per night. The right amount shifts with age: babies need more than twice as much, teenagers still need more than most adults get, and the need for sleep barely drops in later life. The chart below is the quick answer; the rest of this page explains where the numbers come from and how to find your own figure inside the range.
| Age group | Recommended sleep | Notes |
|---|---|---|
| Newborns (0–3 months) | 14–17 hours | Sleep comes in short stretches around the clock. |
| Infants (4–12 months) | 12–16 hours | Includes naps; night sleep consolidates across this year. |
| Toddlers (1–2 years) | 11–14 hours | Includes one or two naps for most children. |
| Preschoolers (3–5 years) | 10–13 hours | Naps usually fade somewhere inside this range. |
| School-age children (6–12 years) | 9–12 hours | Mostly night sleep; consistent bedtimes matter. |
| Teenagers (13–18 years) | 8–10 hours | Body clocks shift later; early school starts fight it. |
| Adults (18–60 years) | 7–9 hours | The range this site's calculators are built around. |
| Older adults (61+ years) | 7–8 hours | Need barely changes; timing and continuity do. |
Ranges are total sleep per 24 hours, including naps for children, from the National Sleep Foundation's duration recommendations2 and the American Academy of Sleep Medicine consensus statements for pediatric3 and adult1 populations. Table: Sleep Time Calculator (calculatorsleeptime.com) · CC BY 4.0
How Many Hours of Sleep Do Adults Need?
The joint consensus statement from the American Academy of Sleep Medicine and the Sleep Research Society puts the adult recommendation at 7 or more hours per night,1 and the National Sleep Foundation's review lands on the same 7–9 hour band for adults aged 18 to 64.2 Seven is the floor, not the target: many adults do better closer to eight or nine, particularly after a run of short nights, during illness, or in heavy physical training.
Individual variation is real, but it is smaller than the internet suggests. The rare “short sleeper” mutation that lets someone thrive on a few hours affects a tiny share of the population. What is common is adaptation: in controlled experiments, volunteers restricted to six hours a night showed measurable lapses in attention and reaction time that kept building over two weeks — while their own ratings of sleepiness plateaued, so they stopped noticing how impaired they were.4 If you need an alarm plus caffeine to function, treat that as data, not personality.
Sleep Needs by Age
Sleep need is highest at birth and declines through childhood and adolescence, then holds roughly flat through adult life. The numbers in the chart above come from two consensus efforts: the National Sleep Foundation's duration recommendations, which cover newborns through older adults,2 and the AASM's pediatric statement, which covers infancy through age 18.3
For newborns (0–3 months), 14–17 hours a day is the recommended range, delivered in short stretches around the clock — a newborn has not yet learned to consolidate sleep at night. From 4 to 12 months, 12–16 hours including naps, with night sleep gradually taking a larger share. Toddlers (1–2 years) need 11–14 hours including one or two naps, and preschoolers (3–5 years) 10–13 hours as naps fade.
School-age children (6–12 years) need 9–12 hours, almost all of it at night — the age where inconsistent bedtimes show up first in classroom attention. Teenagers (13–18 years) need 8–10 hours per 24 hours, and their body clocks genuinely shift later: asking a teenager to fall asleep at 10 PM is biologically closer to asking an adult to sleep at 8 PM.
For adults, 7–9 hours is the recommendation.1 For older adults (61+), the National Sleep Foundation recommends 7–8 hours — the need barely shrinks with age.2 What does change is timing and continuity: bedtimes and wake times drift earlier, and sleep becomes lighter and more easily broken. Sleeping poorly is common in later life; it is not a normal part of aging, and it is worth raising with a clinician.
What Happens When You Don't Get Enough Sleep
The first casualties are attention and reaction time. After a single short night most people feel it; the more dangerous pattern is chronic partial restriction, where the deficits accumulate week over week. In the classic dose-response study, groups restricted to six, four, or no sleep per night all accumulated measurable cognitive deficits, and the six-hour group kept declining without fully registering how sleepy they were.4
Longer-term, short sleep reaches into metabolic and endocrine function: experimental sleep debt has been shown to disturb glucose regulation and hormone profiles in ways that resemble markers associated with metabolic syndrome.5 Missed sleep also behaves like a running tab — the body does not simply forget a short Tuesday. If you want to size up what a week of short nights has actually cost, the sleep debt calculator does the arithmetic.
How to Work Out Your Own Sleep Need
The chart gives you a range; your own number sits inside it. A two-week self-test finds it faster than any quiz:
1. Fix your wake time first. Pick one wake-up time and keep it every day, weekends included. A stable wake time anchors your body clock, and a consistent clock is what makes falling asleep predictable.89 Sleeping in on weekends feels like recovery but mostly shifts the clock you have to fight on Monday.
2. Give yourself a long sleep opportunity. Set bedtime so you have eight hours in bed — not in sleep — for two weeks, and let the amount you actually sleep tell you the answer. Do not force it; just remove the ceiling.
3. Check the three signals. You fall asleep within about 20 minutes of lights out (much longer usually means too much caffeine, too much light, or a shifted clock — typical sleep onset is 10–20 minutes6); you wake without an alarm most days; and you stay alert through the afternoon without caffeine. If all three hold, you have found your number.
Once you know your hours, the sleep calculator converts them into actual bedtimes and wake-up times, and the how sleep cycles work guide explains the 90-minute timing layer on top. Total hours come first; cycle alignment is a refinement, not a substitute.
How Much Sleep Is Too Much?
Yes, there is an upper bound worth watching. An occasional long night after debt or illness is normal recovery. The pattern that deserves attention is regularly sleeping well past nine hours and still waking unrefreshed — needing eleven or twelve hours to feel human is a signal, not a sleep need.
Habitually long sleep is associated with poorer health outcomes in population studies, and it can point to an underlying cause: untreated sleep apnea, depression, certain medications, or another condition making sleep unrefreshing.7 If that describes your weeks, the right next step is a clinician, not a longer lie-in.
Frequently Asked Questions
How much sleep do I need?
For adults, 7–9 hours per night is the consensus range; teenagers need 8–10 and school-age children 9–12. Use the chart above for every other age. If you wake refreshed and stay alert without caffeine, you are inside your own range.
How many hours of sleep do adults need?
Seven to nine, per the joint consensus of the American Academy of Sleep Medicine and the Sleep Research Society. Seven is the floor rather than the target — many adults do better closer to eight or nine, especially after short nights, during illness, or in heavy training.
Is 6 hours of sleep enough?
For most adults, no. A small share of people carry a genuine short-sleep mutation, but lab studies show that chronic six-hour nights produce measurable lapses in attention and reaction time — often without the person feeling sleepy, which is exactly what makes the deficit easy to miss.
How much sleep does a teenager need?
Eight to ten hours per 24 hours, according to the AASM pediatric consensus statement. Adolescent body clocks naturally shift later, so early school start times routinely cut into the back half of that window.
How much sleep do children need?
School-age children (6–12) need 9–12 hours, preschoolers (3–5) 10–13, toddlers (1–2) 11–14, and infants (4–12 months) 12–16. For the younger groups, those totals include naps.
Do older adults need less sleep?
Barely. The adult range holds into later life, with the National Sleep Foundation recommending 7–8 hours for people over 65. What changes with age is timing — earlier bedtimes and wake times — plus sleep becoming lighter and more broken. Poor sleep is common in older age; it is not a normal part of it.
How much sleep is too much?
Regularly sleeping well past nine hours and still waking unrefreshed is worth a conversation with a clinician rather than a longer lie-in. Population studies link habitually long sleep with poorer health outcomes, and it can be a sign of sleep apnea, depression, or a medication effect.
How do I know if I'm getting enough sleep?
Three practical checks: you fall asleep within about 20 minutes of lights out, you wake without an alarm most days, and you stay alert through the afternoon without caffeine. If any check fails for two weeks, give yourself a longer sleep opportunity and re-test.
Sources
Numbers in the text point here. These are peer-reviewed papers, consensus statements, or official public-health pages you can open and check. The calculators still use planning averages; they are not a personal sleep study.
- Watson NF, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843–844.
- Hirshkowitz M, et al. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40–43.
- Paruthi S, et al. Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine. J Clin Sleep Med. 2016;12(6):785–786.
- Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117–126.
- Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet. 1999;354(9188):1435–1439.
- Sleep Foundation. Sleep Latency: How Long Should It Take to Fall Asleep? (typical adult onset about 10–20 minutes).
- Centers for Disease Control and Prevention. About Sleep.
- Czeisler CA, et al. Stability, precision, and near-24-hour period of the human circadian pacemaker. Science. 1999;284(5423):2177–2181.
- National Heart, Lung, and Blood Institute. How Sleep Works: Your Sleep/Wake Cycle.
Turn Your Sleep Hours Into Clock Times
Hours per night are the target. The sleep calculator turns them into real bedtimes and wake-up times, the sleep debt calculator prices a week of short nights, and the tools below cover the adjacent problems — naps, jet lag, and the cycle math itself.