How many hours of sleep do I need? By age, and how to find your number

Most adults need 7 to 9 hours of sleep a night. The American Academy of Sleep Medicine and Sleep Research Society say adults 18 to 60 should get at least 7 hours regularly, and the National Sleep Foundation puts adults 65 and over at 7 to 8 hours. Your own need sits somewhere in that range, and you can find it with a simple two-week test.

One thing many guides skip: hours of sleep and hours in bed are not the same. If you lie awake a lot, adding more time in bed usually makes it worse. Below: the numbers by age, how to find your own, how to set a bedtime that fits it, what changes after 40, and when feeling tired despite enough sleep means seeing a doctor.

How much sleep you need by age

The CDC uses the same figures: 7 or more hours for adults 18 to 60, 7 to 9 for 61 to 64, 7 to 8 for 65 and over. In US surveys, about a third of adults report usually sleeping less than 7 hours.

Is 6 hours of sleep enough?

For most adults, regularly sleeping less than 7 hours is linked to more health problems over time, including weight gain, high blood pressure, heart disease, depression, and more mistakes and accidents. That's why the expert panels set 7 as the floor for adults. A small number of people really do need less, often because of rare gene variants, and they feel fully rested on 6 hours or less without catching up at weekends. Most people who believe they're short sleepers are actually short on sleep: they rely on caffeine, nod off in meetings or sleep 2 hours longer at the weekend.

But don't panic about one short night, or even a run of them. The research is about years of habitual short sleep, and worry about not sleeping enough is itself one of the things that keeps people awake.

Is 9 or 10 hours too much?

Regularly sleeping more than 9 hours is also linked to health problems in studies, but here sleep is often a sign rather than the cause: illness, depression, sleep apnea and some medicines make people sleep longer. If you need more than 9 hours to feel rested, or you sleep long and still feel tired, that's worth raising with a doctor. Sleeping longer for a few nights after a short week, or while ill, is normal.

Hours of sleep vs hours in bed

This is the most useful idea on the page if you sleep badly. A good sleeper in bed for 8 hours sleeps about 7 to 7.5 of them. Someone with insomnia might be in bed for 9 hours and asleep for 5.5, with the rest spent lying awake. Sleep specialists measure this as sleep efficiency: time asleep ÷ time in bed × 100. Good sleepers usually sit around 85% or more.

When sleep is short, the natural move is to go to bed earlier and stay in later to "get the 8 hours". It backfires. The extra time in bed isn't filled with sleep; the same amount of sleep gets spread thinner, with more waking and more time lying there. Over months, that teaches the brain that bed is a place to be awake. CBT for insomnia does the opposite: it shrinks time in bed to roughly the time you actually sleep, then widens it as sleep fills it. That's called a sleep window, and our guide to sleep restriction sets one up step by step.

How to find your own sleep need: a 2-week test

The best time is a holiday or a quiet fortnight with no early starts. If you have insomnia, skip this test and use the sleep window method above instead; long, open-ended time in bed is the thing to avoid.

1. Pick a bedtime you'll keep for 14 nights. Go to bed when sleepy, around the same time each night.
2. Turn off the alarm. Wake when you wake.
3. Note each morning roughly when you fell asleep and when you woke, and rate how rested you feel from 1 to 5.
4. Ignore the first 3 to 5 nights. If you're carrying sleep debt, you'll sleep long at first.
5. Average the last 7 nights. That's close to your natural need.
6. Check it against the day. At your number you should wake without a struggle most days, get through the afternoon without fighting to stay awake, and not need caffeine to function.

Can't take two weeks? Look at the gap between workdays and days off. If you sleep 1 to 2 hours longer when you can, you probably need more than you're getting on workdays.

Signs you're not getting enough

• You need an alarm every day and hit snooze more than once.
• You fall asleep within a few minutes of lying down, every night, or doze off in front of the TV, on the sofa or as a passenger.
• You sleep much longer on days off.
• You feel foggy, irritable or low most afternoons.
• You rely on caffeine to get through the day.

If you feel very sleepy in the day, never drive when drowsy. Pull over and rest.

How to set your bedtime from your wake-up time

Start from the end of the night, because wake-up time is the anchor your body clock follows. Count back your sleep need, then add the time you usually take to fall asleep (for most people 10 to 20 minutes).

The table assumes about 15 minutes to fall asleep. If you lie awake much longer than that most nights, going to bed earlier won't help; use a later bedtime and a sleep window instead. Keep the wake-up time the same 7 days a week, within about 30 minutes; a weekend lie-in shifts your clock later and makes Sunday night harder. Our guide on how to fix your sleep schedule covers moving it if it has drifted.

Do you need sleep in 90-minute cycles?

Sleep runs in cycles of roughly 90 minutes, with deep sleep mostly early in the night and more dream (REM) sleep near the morning. Some calculators tell you to sleep exactly 6, 7.5 or 9 hours so you wake at the end of a cycle. In real life cycles vary from about 70 to 120 minutes and change through the night, so the maths is rough. A steady wake-up time and enough total sleep matter far more than hitting a cycle boundary.

Sleep need after 40, in menopause and in older age

Need doesn't drop much with age: adults 65 and over still need about 7 to 8 hours. What changes is the ability to get it. Sleep gets lighter, with more wakings, and the body clock tends to move earlier, so many older adults get sleepy earlier in the evening and wake earlier in the morning. In perimenopause and menopause, hot flashes, night sweats and mood changes break sleep up for many women (see our guide to perimenopause insomnia). In all of these, lying in bed longer to make up for it tends to bring more broken sleep. A steady window and morning daylight usually help more.

Can you catch up on lost sleep?

Partly. After a few short nights, a longer night or two helps you recover alertness. But regular weekend catch-up doesn't fully undo a week of short sleep, and long lie-ins shift your clock so that Sunday night is hard. Better: an extra 30 to 60 minutes on a couple of nights, keeping the wake-up time close to usual, or a short early-afternoon nap of under 30 minutes if you don't have insomnia. If you do have insomnia, skip naps; they spend the sleep pressure you need at night.

What if you can't get the hours even when you try?

If you give yourself 8 hours in bed and still sleep 5 or 6, the issue isn't the schedule; it's that sleep isn't coming in the time you give it. Insomnia means trouble falling or staying asleep at least 3 nights a week for 3 months, despite enough chance to sleep, and it affecting your day. The treatment guidelines recommend CBT for insomnia first. The free 2-minute sleep quiz works out how much of your time in bed is spent awake and gives you a starting sleep window. For trouble falling asleep at night, see what to do when you can't fall asleep; for a body clock that runs late, see can't fall asleep before 2 a.m..

When to see a doctor

• You sleep 7 to 9 hours but still feel exhausted, or fall asleep in the day when you don't mean to.
• You snore loudly, gasp or stop breathing in your sleep (possible sleep apnea).
• You have an uncomfortable urge to move your legs in the evening.
• You need more than 9 to 10 hours most nights to function.
• Your low mood, worry or loss of interest go along with the sleep change.
• Poor sleep has gone on for 3 months or more, or started with a new medicine.

Frequently asked questions

How many hours of sleep does a woman need?

The guidelines are the same for women and men: 7 to 9 hours for adults. Women report insomnia more often, especially around periods, pregnancy and menopause, so getting those hours can be harder.

Is 7 hours of sleep enough?

For many adults, yes: 7 is the minimum the expert panels recommend. If you wake rested and stay alert in the day on 7, that's likely your number.

Does time awake in bed count as rest?

Lying still with eyes closed is restful, but it isn't sleep, and long stretches awake in bed tend to feed insomnia. Get up if you've been awake and alert for what feels like 20 minutes.

Is it better to sleep 6 hours or 8 hours with wakings?

Broken sleep feels worse than the same amount in one block. People with insomnia often feel better on a shorter, solid window than a long broken one, and then widen it as sleep improves.

Do I need more sleep when I'm sick or exercising a lot?

Often yes, for a while. Illness, hard training and recovering from sleep debt all raise short-term need. Let yourself sleep a bit longer, but keep your wake-up time close to normal.

Find your number

Fix your wake-up time first, then work back to a bedtime from the table above, and keep both for two weeks. If the problem is that sleep won't come in the hours you give it, take the free sleep quiz for a starting sleep window. For more on schedules, falling asleep and night waking, see all our sleep guides.

Sources: 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. Hirshkowitz M et al., National Sleep Foundation's sleep time duration recommendations, Sleep Health, 2015. Paruthi S et al., Recommended amount of sleep for pediatric populations, AASM consensus statement, Journal of Clinical Sleep Medicine, 2016. Centers for Disease Control and Prevention, About sleep: how much sleep do I need?. American Psychiatric Association, DSM-5-TR criteria for insomnia disorder. Edinger JD et al., AASM clinical practice guideline on behavioural treatments for chronic insomnia, 2021. This guide is education, not medical advice.