How Much Sleep Do Adults Need by Age?
Seven to nine hours for most adults, seven to eight after 65. The need does not fall much with age, but the ability to get it does. What the guidance says and why.
In short
Most adults aged 18 to 64 need 7 to 9 hours of sleep a night, and adults over 65 need 7 to 8. Teenagers need 8 to 10. The requirement declines only slightly with age; what changes is that older adults find it harder to get, with lighter sleep and more waking. Regularly getting under 6 hours is associated with measurably worse health.
Sleep need is one of the more stable numbers in health guidance. Bodies in different countries, using different evidence reviews, have arrived at nearly the same ranges, and those ranges have barely moved in a decade.
The ranges
- Teenagers, 14 to 17: 8 to 10 hours
- Young adults, 18 to 25: 7 to 9 hours
- Adults, 26 to 64: 7 to 9 hours
- Older adults, 65 and over: 7 to 8 hours
The adult range is wide because people genuinely differ. Some are fine at seven, some need nine, and the way to find your own figure is to notice how many hours you sleep when you have no alarm and no debt to repay, after a week or so of that.
The myth that older people need less
The requirement drops only slightly, from a 7 to 9 range to 7 to 8. What changes with age is the ability to sleep: lighter sleep, more frequent waking, earlier waking, and less of the deep slow-wave stage. Older adults often get less sleep than they need and attribute it to needing less, when the more accurate description is that they are short of it.
What happens below the range
Regularly sleeping under six hours is associated with higher rates of cardiovascular disease, diabetes, obesity, depression, weakened immunity and accidents. Some of that is correlation with the things that cause short sleep, such as shift work and stress. Some of it holds up in controlled studies, where restricting sleep produces measurable changes in blood sugar handling and appetite within days.
The performance effects are better established than people expect. After two weeks on six hours a night, participants in restriction studies perform on attention tasks like people who have been awake for 24 hours straight, and they rate themselves as only slightly tired. The impairment is real and the perception of it fades.
The short-sleeper exception
A small number of people carry a rare genetic variant that allows them to function normally on around six hours or less. It is genuinely rare, far rarer than the number of people who believe they have it. The honest test is whether you sleep longer given the chance, and whether you are sharp on five hours or merely used to it.
Timing and consistency
Two people can both get seven and a half hours and have very different sleep quality, depending on when they get it. A consistent bedtime and wake time, including at weekends, strengthens the internal clock and improves sleep depth. Large swings between weekday and weekend timing, sometimes called social jet lag, produce grogginess on Monday that has nothing to do with total hours.
Finding your number
Sleep with no alarm for a week, ideally on holiday, once any debt is repaid. The hours you settle into are your requirement. For most adults it lands between seven and a half and eight and a half, and the surprise is usually that it is more than they had assumed.
Common questions
Can some people function on 5 hours?
A very small number of people carry a genetic variant that genuinely reduces their need. For everyone else, feeling fine on five hours is adaptation to impairment rather than absence of it. Reaction time, memory and judgement tests show deficits that people stop noticing after a few days.
Is it bad to sleep more than 9 hours?
Regularly needing more than nine can be a sign of poor sleep quality, an underlying condition or catching up on debt, rather than being harmful in itself. If you routinely sleep long and still wake tired, that is worth raising with a doctor.
Does the amount of sleep matter more than the timing?
Both matter. A consistent schedule improves sleep quality at any duration, and irregular timing is associated with worse outcomes even when total hours are adequate. Going to bed and waking at the same times is the single most effective habit for most people.
Sources
Every factual claim above traces to one of these. Follow them rather than taking this article's word for it.
- Sleep and tiredness NHS
- How much sleep do we really need? Sleep Foundation
- Insomnia NHS
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