How Much Sleep Do I Need?
The honest answer is a range that narrows with age: most adults need 7–9 hours, children need more, and where you personally sit inside your band is testable. This guide gives the standard by-age numbers and a practical way to find your own.
Recommendations by Age (National Sleep Foundation)
| Age group | Recommended |
|---|---|
| Newborn (0–3 months) | 14–17 h |
| Infant (4–11 months) | 12–15 h |
| Toddler (1–2 years) | 11–14 h |
| Preschool (3–5 years) | 10–13 h |
| School age (6–13 years) | 9–11 h |
| Teenager (14–17 years) | 8–10 h |
| Adult (18–64 years) | 7–9 h |
| Older adult (65+) | 7–8 h |
Finding Your Number Inside the Range
Hold a consistent schedule for two weeks and watch two signals: whether you wake near your alarm without it, and whether you stay alert through the afternoon without caffeine rescue. Drifting toward long weekend lie-ins is a debt signal — your weekday number is too low. Once you know the duration, structure it in whole 90-minute cycles with the sleep calculator (5–6 cycles covers the adult band; the mechanics are in the sleep cycle length guide).
What Short Sleep Actually Costs
Chronic sleep below the range measurably degrades attention, mood, glucose regulation, immune function, and appetite hormones — the last of which quietly fights any calorie plan you run through the TDEE calculator. The deceptive part: subjective sleepiness plateaus after a few short nights while measured performance keeps falling, so "I've adapted to six hours" is usually the deficit talking. Genuine sub-6-hour sleepers exist but are genetically rare.
Frequently Asked Questions
How much sleep does an adult need?
The National Sleep Foundation recommends 7–9 hours for adults 18–64, and 7–8 hours for adults 65 and
older.
Can I train myself to need less sleep?
No. People adapt to feeling less sleepy, but measured performance keeps declining with chronic short sleep.
True short sleepers who thrive on under 6 hours are genetically rare.
Is sleeping more than 9 hours harmful?
Occasional long sleep is normal recovery. A persistent need for more than 9–10 hours with daytime sleepiness
is worth discussing with a clinician.