How much sleep do I need?

The short answer

Most healthy adults need around 7 to 9 hours of sleep a night, and the NHS says the exact amount can be different for each person. Two expert groups support that range. The American Academy of Sleep Medicine (AASM) and the Sleep Research Society say adults should sleep 7 or more hours a night on a regular basis, and a National Sleep Foundation panel recommends 7 to 9 hours for most adults.

So the useful question is not only how many hours you get. It is whether you wake up feeling rested and stay alert through the day. Chaput and colleagues, reviewing sleep needs across the lifespan, call that a generally valid test and conclude there is no “magic number” for everyone.

Recommended sleep by age

The National Sleep Foundation brought together 18 experts to review the research. These are the ranges they recommend for healthy people without a sleep disorder, in hours of sleep per day.

The panel also described wider “may be appropriate” ranges for some people. Source: Hirshkowitz and colleagues, 2015.

The AASM and Sleep Research Society statement covers adults and is firmer about the lower end. It links regularly sleeping fewer than 7 hours with poorer health, including weight gain, diabetes, high blood pressure, heart disease and depression. It sets no upper limit: more than 9 hours may be appropriate for young adults, people recovering from sleep debt and people who are ill.

Why your number may differ

Those ranges describe groups of people. Within a group, individuals vary, partly for genetic reasons. Kitamura and colleagues tested this in a laboratory, giving volunteers several days of extended time in bed and tracking how their sleep settled. They found that each person’s optimal sleep duration was different. The ranges above also assume nothing is getting in the way, such as a sleep disorder.

How to find your own number

You can get a rough answer at home. This is a practical take on the laboratory idea above, not a validated test, so treat the result as a starting point.

1. Pick a quiet stretch. About two weeks with few early alarms and late nights works best, such as a holiday.
2. Leave plenty of room. Be in bed for around 9 hours at the same time each night and let yourself wake naturally.
3. Expect long nights at first. If you have been short on sleep, you will probably sleep more to begin with. Kitamura’s group found that this rebound in sleep time is a simple sign of sleep debt.
4. Watch the later nights. Once your sleep settles, the typical length of those nights is a rough guide to what you need.
5. Check how you feel. Waking without much struggle, steady energy and no heavy afternoon slump say more than any number.

Keep the other things that affect sleep steady while you test. The NHS advises going to bed and getting up at around the same time each day, setting aside time to relax before bed, and avoiding caffeine and alcohol in the hours before you sleep.

Consistency matters too

Regular times help your body clock settle. Weekend lie-ins are a common way to make up for a short week, but in a small laboratory study of 36 healthy young adults, Depner and colleagues found that weekend recovery sleep did not prevent the metabolic changes that came with short nights during the week. Take it as a hint rather than a rule.

Sleep debt

Sleep debt is the gap between the sleep you need and the sleep you get, adding up night after night. It can be easy to miss. In a laboratory experiment by Van Dongen and colleagues, healthy adults were limited to 6 hours in bed for 14 nights. Their performance on attention and memory tasks got steadily worse, while their ratings of how sleepy they felt rose early on and then barely changed. Feeling fine is not proof that you are getting enough.

Paying a debt back takes longer than you might hope. Kitamura’s group estimated that even one hour of sleep debt took about four days to recover. Going to bed a little earlier over several nights is a gentler route than one very long lie-in.

When to talk to a doctor

The figures on this page are for healthy people. If you get enough hours but still feel exhausted, if you snore loudly or someone notices you stop breathing at night, or if trouble falling or staying asleep has lasted for weeks, speak to a GP or pharmacist.

Vital gives general information about fitness and wellbeing. It is not medical advice, and it does not diagnose or treat any condition.