Body · Sleep basics
How much sleep you need
Adults need 7 to 9 hours a night. The biggest lever is a steady schedule: same bedtime and wake time every day, within about an hour on weekends.
What to know
- Aim for 7 to 9 hours. Adults who sleep less than 7 hours a night may have more health problems. Source: NHLBI
- Pick a wake time and keep it every day. Keep weekends within about an hour of weeknights. Source: NHLBI
- Turn off screens at least 30 minutes before bed, and keep the room quiet, relaxing and cool. Source: CDC
- Cut caffeine in the afternoon. Its effects can last up to 8 hours. Source: NHLBI
- Skip large meals and alcohol close to bedtime. Source: CDC
Watch out If you feel sleepy even after enough sleep, or have trouble sleeping most nights, talk to a doctor. It could be a sleep disorder. Source: CDC
If it doesn't work
- Can't fall asleep at night? Limit naps, or take them earlier. NHLBI says adults should nap no more than 20 minutes. Source: NHLBI
- Working shifts? Try light-blocking curtains, limit caffeine to the first part of your shift, and limit shift changes when you can. Source: NHLBI
- Still struggling after a few weeks? A doctor may ask you to keep a sleep diary. Source: CDC Start one now: bedtime, wake time, caffeine, naps.
Good to know
Sleep and driving
Enough sleep lowers the risk of car crashes. Source: CDC
More than 9 hours
Sleeping more than 9 hours isn't necessarily harmful and may help young adults or people catching up on lost sleep. Source: NHLBI
Hidden caffeine
Caffeine is in soda, tea and chocolate too, not just coffee. Source: NHLBI
Sources
- National Heart, Lung, and Blood Institute How much sleep is enough?
- National Heart, Lung, and Blood Institute Healthy sleep habits
- Centers for Disease Control and Prevention About sleep
Lesson B1.1 · Last checked October 2, 2026 against the sources listed.
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