Seven hours isn’t a compromise and eight isn’t a target. The adult recommendation has no upper bound at all — which tells you more about how it was built than any round number does.
The short answer
Seven or more. There is no official upper number.
The American Academy of Sleep Medicine and Sleep Research Society consensus is that adults should sleep 7 or more hours per night on a regular basis. That’s a floor, not a range. The CDC keeps the ceiling open for ages 18–60 and closes it only later — 7–9 hours at 61–64, 7–8 at 65 and over. No authority names eight as the target.
Key takeaways
- Every band up to age five is stated per 24 hours, naps included. Teens 13–17 need 8–10 hours.
- Cycles aren’t 90 minutes. The first runs 70–100 minutes and later ones 90–120, so alarm arithmetic built on a fixed 90 drifts further wrong with every cycle.
- Deep sleep sits in the first third of the night; REM is longest in the last third. The two ways of cutting a night short cost different things.
- Sleep inertia usually clears within 30 minutes, but full recovery can take at least an hour.
- In testing, performance on an addition task immediately after waking was more impaired than after a night of sleep deprivation. Grogginess isn’t a mood.
The numbers, by age
These are the CDC’s bands, built on the AASM, Sleep Research Society and National Sleep Foundation consensus statements. Hours are per 24 hours.
| Age group | Recommended sleep | Notes |
|---|---|---|
| Newborn, 0–3 months | 14–17 hours | Not a schedule you control |
| Infant, 4–12 months | 12–16 hours | Including naps |
| Toddler, 1–2 years | 11–14 hours | Including naps |
| Preschool, 3–5 years | 10–13 hours | Including naps |
| School age, 6–12 years | 9–12 hours | Naps no longer counted in |
| Teen, 13–17 years | 8–10 hours | AASM’s own statement runs this band to 18 |
| Adult, 18–60 years | 7 or more hours | No upper figure stated |
| Adult, 61–64 years | 7–9 hours | A ceiling appears |
| Adult, 65+ years | 7–8 hours | The narrowest band on the table |
Why the adult number has no ceiling
“Seven or more hours per night on a regular basis” is the AASM and Sleep Research Society wording, and the phrasing is deliberate. A floor is a claim the evidence supports. A ceiling would be a claim about how much sleep is too much — and the adult consensus didn’t make one.
The CDC does make it, twice, and late. At 40, sleeping nine hours puts you inside every published recommendation. At 70, the same nine hours puts you outside one.
The phrase carrying the real weight isn’t the number. It’s on a regular basis. Seven hours every night is a different thing from five, five, five, five and ten.
Sleep cycles aren’t 90 minutes
The 90-minute figure is an average of numbers that aren’t near each other. The National Academies’ sleep physiology review puts the first NREM–REM cycle at 70 to 100 minutes and later ones at roughly 90 to 120.
That’s what breaks the alarm arithmetic. If your first cycle runs 75 minutes and your third runs 115, a wake time set at five times 90 lands somewhere nobody can predict — and the error compounds across the night rather than averaging out.
Cycle-timing apps sell a calculation the physiology doesn’t support. Cycles run 70–100 minutes early and 90–120 later, vary between people, and vary night to night in the same person. A wake time you keep seven days a week is worth more than one computed to the minute — and it costs nothing.
Deep sleep early, REM late
Slow-wave sleep is concentrated in the first third of the night. REM increases as the night goes on and is longest in the last third.
So the two ways of losing sleep take different things. A late bedtime shaves off deep sleep you never reach. An early alarm mostly costs REM. A night broken in the middle takes some of each — which is why the same total hours can leave you fine one week and wrecked the next.
That front-loaded deep sleep is also where physical repair sits, which is why sleep and muscle recovery is mostly a question about the first half of the night, and why a late caffeine dose is more expensive than it looks.
Why waking up hurts
Sleep inertia is the name for it, and it’s been measured. In one comparison, performance on an addition test immediately after waking was significantly more impaired than after a full night of sleep deprivation.
It typically returns to pre-sleep levels within 30 minutes, though full recovery may not be complete until at least an hour after waking. Three things make it worse:
- Sleep depth at the moment you wake. Response speed slowed as depth increased, most sharply from slow-wave sleep.
- Prior sleep loss. Inertia is worse when you’re already behind.
- Circadian timing. Effects are greatest during the biological night, near your core body temperature low.
A 4 a.m. alarm at the end of a short week is therefore a genuinely different event from the same alarm at the end of a rested one.
Finding your own number
Run it as an experiment rather than an argument. On a week you can afford it, go to bed when you’re tired and wake without an alarm. Discard the first few days — those are backlog clearing, not signal.
- You wake at roughly the same time each morning, unprompted.
- You’re alert mid-afternoon without caffeine holding you up.
- You aren’t unconscious the second your head lands. That’s overtiredness, not a talent.
What to actually do
Do the free thing first: fix your wake time, seven days a week, and set a bedtime that gives you seven hours before it. Every recommendation on this page is written in terms of a regular schedule, so that one change is the input all of them assume.
Give it two weeks before you spend anything on a tracker or a cycle-timing app. Then work on quality — the ideal bedroom, sleep hygiene mistakes, better sleep naturally. If you’re getting seven-plus hours on a steady schedule and still waking unrefreshed week after week, that’s a provider conversation, not a scheduling one.
Questions people ask
I sleep six hours and feel fine. Am I a short sleeper?
The consensus sets 7 or more on a regular basis and makes no exception for people who feel fine. Run the no-alarm week before deciding. If your body settles at six on its own, you have your answer. If it settles at seven and a half, you were running a deficit and calling it a personality.
Should I set my alarm to a multiple of 90 minutes?
The arithmetic doesn’t survive contact with the physiology. First cycles run 70–100 minutes, later ones 90–120, and the error compounds all night. A wake time you actually keep every day is worth more than any calculation.
Is nine hours too much?
Not between 18 and 60 — that band is “7 or more” with no stated ceiling. The CDC closes it at 7–9 from 61 and 7–8 from 65. Regularly needing far more than your band, or sleeping long and still waking unrefreshed, is worth raising with a provider.
Do naps count toward the total?
Up to age five, explicitly yes — those bands are written per 24 hours including naps. From school age onward the recommendations are stated per night, so an afternoon nap doesn’t substitute for the floor.
Why am I groggier after eight hours than after six?
Probably the stage you were pulled out of. Inertia is worst coming out of slow-wave sleep, worse after prior sleep loss, and worse near your core-temperature low. Total hours are only one of three inputs, and not the strongest.
Sources
- About Sleep — recommended hours by age — US Centers for Disease Control and Prevention, reviewed 2023.
- Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society — Journal of Clinical Sleep Medicine, 2015;11(6):591–592.
- Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine — Journal of Clinical Sleep Medicine, 2016;12(6):785–786.
- Sleep FAQs: recommended sleep durations — Sleep Education, American Academy of Sleep Medicine.
- Sleep Physiology — in Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Institute of Medicine / National Academies Press, 2006.
- Sleep inertia: current insights — Nature and Science of Sleep, 2019;11:155–165.
How we make money. Some links on this page are affiliate links. If you buy through one, we may earn a commission at no extra cost to you. It does not change what we write — see our affiliate disclosure.
These statements have not been evaluated by the Food and Drug Administration. CBD products are not intended to diagnose, treat, cure or prevent any disease. Serene Leaf does not physically test products; our assessments are based on published research, third-party lab reports and publicly available product information.
This article is information, not medical advice. Talk to a qualified healthcare provider before starting any supplement — especially if you are pregnant, nursing, taking medication or managing a diagnosed condition. 21+ only.