There is no single right number of hours. There is a range, it moves as you age, and two expert panels have written it down: the American Academy of Sleep Medicine (AASM), which published consensus statements for children in 2016 and for adults in 2015, and the National Sleep Foundation (NSF), whose panel reported its ranges in 2015. They agree more than they differ. Here are both, side by side, and then what the numbers can and cannot tell you.
The recommended hours of sleep at each age
The AASM gives its pediatric ranges per 24 hours, naps included. The NSF lists a "recommended" band for each age group, with wider "may be appropriate" margins on either side that are left out here.
| Age | AASM (2016 children, 2015 adults) | National Sleep Foundation (2015) |
|---|---|---|
| Newborn, 0–3 months | no recommendation | 14–17 hours |
| Infant, 4–12 months | 12–16 hours | 12–15 hours (4–11 months) |
| Toddler, 1–2 years | 11–14 hours | 11–14 hours |
| Preschool, 3–5 years | 10–13 hours | 10–13 hours |
| School age, 6–12 years | 9–12 hours | 9–11 hours (6–13 years) |
| Teenager, 13–18 years | 8–10 hours | 8–10 hours (14–17 years) |
| Adult, 18–60 years | 7 hours or more | 7–9 hours (18–64 years) |
| Older adult, 65+ | 7 hours or more | 7–8 hours |
Two things stand out. The ranges overlap almost completely: where the panels differ, it is by an hour at the edges or by where they draw the age lines. And the adult number from the AASM is a floor, not a band. The 2015 adult statement, written jointly with the Sleep Research Society, says adults should sleep 7 or more hours a night on a regular basis; it adds that more than 9 hours may suit young adults, people recovering from sleep debt and people who are ill, and that for others it is uncertain whether longer sleep brings any harm.
Why babies and children need so much more
A newborn sleeps in short bouts around the clock, and a large share of that sleep is active, the infant form of REM sleep. Over the first year the bouts gather into a long night and a few naps, and the total falls. By school age most children sleep in one long block, and the need drops another hour or two. The National Institute of Neurological Disorders and Stroke notes that sleep is involved in growth, learning and memory; a child's day contains a great deal of all three.
For young children, the AASM counts naps in the total. A two-year-old who sleeps ten hours at night and naps for ninety minutes is near the middle of the 11–14 hour range. When naps are dropped, around age four or five for most children, the night has to grow to make up the difference.
Teenagers: more need, later clocks
The teenage range, 8–10 hours, is the one most often missed. During puberty the internal clock shifts later: many teenagers simply do not feel sleepy at ten. School still starts early, so the night is cut from both ends. The AASM statement on children notes that regularly sleeping fewer hours than recommended is associated with attention, behaviour and learning problems in this age group. A teenager who sleeps until noon on Saturday is often repaying the week rather than being lazy.
Adults: seven is the floor, not the target
For adults, both panels land on roughly the same place: seven hours as the lower line, nine as the usual upper one. Seven hours of sleep is not seven hours in bed. Falling asleep takes time, most people wake briefly several times a night, and a night that looks like eight hours on the clock can hold well under seven of actual sleep.
If you want to know when to go to bed to get a given number of hours, the sleep calculator counts backwards from your alarm in whole sleep cycles. The physiology behind it is simple: sleep runs in cycles of light sleep, deep sleep and REM sleep, each roughly an hour and a half long in adults according to StatPearls' summary of sleep stages, and waking at the end of a cycle tends to feel easier than waking out of deep sleep. Five cycles is about seven and a half hours; six is about nine.
Older adults: the need holds, the night changes
It is often said that older people need less sleep. The panels disagree only mildly: the NSF lowers the band to 7–8 hours from 65, and the AASM keeps 7 or more for all adults. What changes far more is the shape of the night. Deep sleep thins out, waking during the night becomes more common, and the body clock tends to drift earlier, so evenings get sleepy and mornings start before dawn. Sleeping less because the night is broken is not the same as needing less.
What the numbers leave out
A range describes a population, not you. Inside the adult band, some people feel fine at seven hours and others need nine. A few useful questions to set against the chart:
- Do you wake without an alarm on free days, and at roughly what time? Your natural wake time on a holiday week, after the first few catch-up days, is a fair hint of your real need.
- Are you sleepy in the afternoon when you sit still? Regular drowsiness in quiet moments is a sign the night is too short or too broken.
- Is your schedule regular? The same hours shifted around through the week feel worse than the same hours kept steady.
None of this is medical advice. If you sleep within the range and still wake tired most days, or if someone tells you that you stop breathing or snore loudly at night, that is worth raising with a doctor.
Sleep length and dreams
There is a reason a dream site cares about this. Dreaming happens throughout the night, but REM periods grow longer towards morning, so the last hour or two of sleep holds a large share of vivid dreaming. Cut the night short, and the dream-richest stretch is what you lose first. People who say they never dream are often people whose alarm goes off in the middle of that stretch, and who have no habit of catching what was there. Our guide on how to remember your dreams covers the habit. And if the dream you catch is one of the common ones, such as falling, its entry sets out what the old dream books and the psychologists made of it.
If you tend to wake from a long morning dream feeling you were somewhere specific, write it down before you check your phone. A few words are enough; the rest often comes back once you start.
How to use this table
Pick your row, note the range, and compare it with what you actually get on a normal week rather than a good one. If you are under the range most nights, start by moving bedtime earlier by fifteen minutes at a time rather than by an hour at once; sudden changes rarely stick. Then let the sleep calculator find bedtimes that end on a full cycle for your alarm.
The figures in the table come from the consensus statements listed below. Each panel looked at the published research and voted on ranges; they are agreements among experts, not laws of nature, and both panels say individual need varies.