How many hours should you sleep?
You need 7–9 hours of sleep each night to maintain cognitive performance, regulate metabolism and support your immune system. But the exact amount depends on your age and individual needs.
How much sleep at each age?
Research-based recommendations from the National Sleep Foundation and CDC:
| Age group | Age | Recommended hours |
|---|---|---|
| Newborns | 0–3 months | 16–17 hours |
| Infants | 4–12 months | 12–16 hours |
| Toddlers | 1–2 years | 11–14 hours |
| Preschool children | 3–5 years | 10–13 hours |
| School-age children | 6–12 years | 9–12 hours |
| Teenagers | 13–18 years | 8–10 hours |
| Adults | 18–64 years | 7–9 hours |
| Older adults | 65+ years | 7–8 hours |
Note: Some people need less or more sleep. Feeling rested and focused after 6 hours, or needing 10 hours, can reflect individual differences.
What matters for sleep quality?
Circadian rhythm
Go to bed and wake up at the same time each day. Consistency matters more than the number of hours.
Natural light
Get sunlight in the morning (at least 30 minutes). It can reduce afternoon sleepiness and improve sleep quality.
Sleep conditions
A dark, cool (around 16–18°C), quiet room is ideal. Put your phone away at least 30 minutes before bed.
Avoid caffeine
Last coffee after 14:00? Its half-life is about 5 hours. Taking it too late can interfere with falling asleep.
Sleep cycles
Sleep follows roughly 90-minute cycles. Waking at the end of a cycle is usually easier. The calculator helps you find a suitable time.
Reduce stress
Evening meditation, yoga or deep breathing can calm the nervous system and make falling asleep easier.
Refine your sleep schedule
The Biohac sleep calculator uses sleep cycles to suggest times. Enter when you want to wake up or fall asleep, and we will calculate suitable bedtimes.
Open sleep calculator