How Much Sleep Do You Really Need? What the Research Says

Two healthy adults can sleep an hour apart every night and both be inside the guidelines, because the expert panels that set them give a range for each age rather than one number. No panel can tell you your own figure. What the research offers is that band, plus some plain daytime signs that tell you whether you get enough.

So how much sleep do you need? For healthy adults, a 2015 expert panel of the US National Sleep Foundation recommends 7 to 9 hours a night, and 7 to 8 hours from age 65.¹ A 2015 US consensus from the American Academy of Sleep Medicine (AASM) and the Sleep Research Society puts it as 7 or more hours for adults up to 60.² Children and teenagers need more. To find where you sit:

1. Look up your age band in the table below.
2. Log your sleep in a simple diary over a few weeks: bedtime, waking time, naps and your alertness during the day (the box near the end shows how).
3. Judge the result by your days. Tired on most days can mean too little sleep, or a problem a doctor should look at.

Habits that make more sleep possible live in the guide to sleeping better, habit by habit. What follows sticks to the numbers: where they come from, why they are ranges and what they can and cannot tell you.

How much sleep do you need at each age?

Recommended sleep falls steadily from birth to adulthood in the National Sleep Foundation’s recommendations, shown in the middle column below.³ The WHO and health bodies in the US, UK and Canada give very similar bands.

The bands line up closely, and some bodies adopted the foundation’s numbers outright: Australia’s Sleep Health Foundation says its own table is based on the 2015 panel. It also explains the table’s shape. Sleep need falls through childhood and settles at around age 20, and older people spend more time in bed but, unless a sleep problem has developed, need about as much sleep as they did as younger adults.⁹ The US panel differs slightly here: its band for people over 65 tops out an hour lower.¹

Picture a household with a four-year-old, a fifteen-year-old and two parents. The table says the preschooler needs roughly half again as much sleep as the parents, and the teenager about an hour more than them, which is worth knowing before a late family evening. Find your own age band first, and treat it as a zone to aim for.

Why sleep guidelines give a range

Sleep guidelines give ranges because they are expert judgments on evidence that is mostly observational, and because healthy people differ. The National Sleep Foundation’s 2015 panel says sleep outside its ranges may suit some people, but that sleeping far outside them is rare and can signal a health problem.¹

Neither panel could read a personal number off the research, so both reached their figures by structured expert agreement. The AASM and Sleep Research Society panel screened more than 5,000 scientific articles on outcomes from heart and metabolic health to mood, performance and death rates, then held several rounds of evidence review, discussion and voting. Even so, it set a floor rather than a band. It said sleeping more than 9 hours regularly may be appropriate for young adults, people recovering from sleep debt and people who are ill, and that for everyone else it is uncertain whether long sleep carries any health risk.²

So the two panels agree on the floor and part ways on the ceiling: the case against regular short sleep is clearer than the case against long sleep. The foundation adds that an extra hour or two on either side of a band may be appropriate for some people.³ A 2026 review of the following decade of meta-analyses, funded by the foundation and co-written by the lead author of its 2015 report, found none that contradicted the recommendations (about a quarter were inconclusive) and kept them unchanged; its full text was not accessible to us, only the abstract.¹⁰

Myth

Everyone needs 8 hours of sleep.

Fact

No expert panel names one number for everyone. Adults get a range, and healthy people land at different points within it.

Two colleagues of the same age can both be inside the range: one is sharp all day on the lower end, the other needs close to the top to feel the same. Neither is doing it wrong. The range describes where most healthy people do well, and your alertness through the day tells you where in it you sit.

Why your own sleep need differs from someone else’s

Individual sleep need is shaped by genetic, behavioral, medical and environmental factors, the 2015 AASM and Sleep Research Society panel wrote, adding that its biology still needs more research.² The common gene variants found so far each move typical sleep length only a little, by a matter of minutes.

Sleep length does run in families: twin and family studies put the heritable share of its variation at anywhere from about a tenth to nearly half. Yet when a 2019 study scanned the genomes of nearly half a million UK Biobank adults of European ancestry, each of the dozens of regions it linked to self-reported sleep length had a small effect. People carrying the most sleep-lengthening variants reported sleeping about 22 minutes longer than those carrying the fewest.¹¹ That is real but small next to the two-hour width of the adult range, so the variants found so far are unlikely to explain why you get by on far less than the people around you.

The famous exception is the natural short sleeper, described in genetic studies of a few families: people who sleep 4 to 6 hours with no apparent harm to their mental health or wellbeing. A 2022 study led from the UK’s University of Exeter checked the gene variants reported in those families against data from about 192,000 people in population studies in the UK, Finland and the US. The carriers of those short-sleep variants it found in UK data reported sleeping about as long as everyone else, and the authors suggest the variants may have much weaker effects than first reported, or that some may not cause short sleep at all.¹²

Your genes have a separate say in when you sleep, which is why some people lean toward mornings and others toward late nights; how chronotypes place you between lark and owl covers that question. For how long you sleep, the answer is simpler. If you regularly sleep well below the adult range and lean on caffeine through the afternoon, the short-sleeper label probably does not fit you.

What the U-shaped health curve can and cannot prove

In long-term cohort studiescohort study: A study that takes a group of people, records something about them, and then follows them to see who ends up with a given outcome. It can show that the outcome is more common in one group; it cannot show that the recorded thing is the reason, because the groups may differ in other ways.Full entry in the glossary, people who report sleeping much less or much more than about 7 hours have higher death rates than people who sleep around 7, so the curve looks like a U. That pattern is an association only, and its long-sleep arm is the harder one to interpret.

The study

Moderate evidence

Higher death rates at both ends of the sleep range, pooled from 27 cohorts (2010)

Francesco Cappuccio’s team at the UK’s University of Warwick pooled 16 prospective studies from Europe, Asia and the US, covering 27 cohorts and about 1.4 million people followed for 4 to 25 years. Compared with the reference group (7 hours a night in most studies), short sleepers had a 12 percent higher relative risk of death over the follow-up and long sleepers a 30 percent higher one. The paper reports relative risks only, so the absolute number of extra deaths is not given.¹³

That is a meta-analysismeta-analysis: A study that combines the results of earlier studies on the same question into one overall estimate. Pooling makes the estimate more precise, but it cannot repair the studies it pools: a meta-analysis of surveys is still survey evidence.Full entry in the glossary of observational studies, and it cannot prove that the hours themselves cause harm. A larger 2025 meta-analysis of cohort studies, whose lead author edits the journal that published it, found the same pattern, again with the bigger relative risk at the long end.¹⁴ A 2017 dose-response meta-analysis that pooled cohorts from Europe, the US, Asia and Australia found the same U shape, lowest at about 7 hours, and its authors list the weak points themselves. Nearly all the studies used self-reports of sleep length, and a single measurement may not capture how sleep changes over the years. Adjusting for other risks cannot rule out confounding that was never measured. And the arrow can run backward: illnesses such as sleep apneasleep apnea: A condition in which breathing repeatedly stops and starts during sleep, often with loud snoring, gasping and daytime sleepiness. It needs a sleep test and a doctor to diagnose; a phone or watch alert can prompt a test but cannot rule it in or out.Full entry in the glossary can raise the need for sleep, and long sleep goes together with depressive symptoms, low income and unemployment, all of which carry their own risks.¹⁵

1. Shorter sleep: linked to a higher death rate in pooled cohort studies; in one short randomized trial, sleeping longer cut how much people ate
2. The low point: the lowest risk sat at about 7 hours a night in one 2017 pooled analysis of cohort studies
3. Longer sleep: also linked to a higher death rate, but illnesses such as sleep apnea can lengthen sleep, and long sleep travels with low mood and low income, so the arrow may point the other way

Across: usual sleep length, as people reported it. Up: death rate relative to the low point. A schematic of the shape, not measured values, and an association, not a cause.

The short-sleep side has more support from experiments. A randomized trial from the University of Chicago (US), published in 2022, gave young adults with overweight who habitually slept short a single counseling session on sleep habits. Over the next two weeks they slept longer than a comparison group and ate about 270 fewer calories a day. It was small and short, and calorie intake is only a marker.¹⁶

An older relative who sleeps long every night and still dozes in the afternoon shows the limit. The curve cannot tell you whether the long nights are hurting him or whether something that is making him unwell is also making him sleep more. For him, the useful step is a check-up.

What too little sleep looks like during the day

The clearest sign of too little sleep shows up in your day, not your night: the UK’s NHS says that feeling constantly tired during the day probably means you are short of sleep.⁶ The US National Heart, Lung, and Blood Institute (NHLBI) lists feeling sleepy in the day, waking unrefreshed and dozing off during routine tasks, especially driving, as things to raise with a doctor.¹⁷

Signs to watch for in an ordinary week

• Tired on most days, not only after a late night
• Rarely waking up refreshed
• Nodding off in quiet moments, such as a long meeting, reading or as a passenger
• Struggling to stay awake while driving
• Sleeping far longer on days off than on workdays

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Doctors ask when you go to bed and get up on workdays and on days off, the NHLBI notes.¹⁷ A big gap between the two can be a sign that a debt is building, which how sleep debt builds and how much a lie-in repays explains. The sign that matters most is sleepiness that keeps coming back, whatever the hours.

Enough hours but still sleepy: when to see a doctor

See a doctor if you often fall asleep during the day or sleepiness is affecting your life, the UK’s NHS advises; causes it lists include sleep apnea, narcolepsy and depression, and it notes that changing sleep habits alone may not cure the sleepiness.¹⁸ We have sorted advice from health services in the UK, US and Australia by urgency; readers elsewhere can take the same questions to their own doctor or national health service.

• Now: if you feel drowsy, stay off the road, the NHS advises.⁶ If tiredness comes with low mood and thoughts of suicide or self-harm, reach out straight away: phone the emergency number for your area first, or a local crisis line; Find A Helpline, an international directory, lists free helplines by country.¹⁹ Readers in the US can phone or text 988, the free Suicide & Crisis Lifeline, day or night.²⁰
• Soon: book an appointment if you often fall asleep during the day, or if sleepiness comes with loud snoring, strange feelings in your legs at night or low mood, which the NHS lists as signs of possible causes to look into.¹⁸
• At your next appointment: healthdirect, Australia’s government-funded health advice service, says to see your doctor if you regularly wake up unrefreshed or find that being tired is affecting your mood.²¹ A sleep diary kept beforehand gives the doctor something to work with.

The bottom line

Start from your age band: for most adults that means aiming for 7 to 9 hours of actual sleep. If you are regularly below it and tired in the day, protect more sleep first. If you sleep within it, or longer, and still struggle to stay awake, see a doctor before adding more time in bed.