How much sleep you need

Adults need 7 to 9 hours a night, and losing just 1 to 2 hours a night for several nights hurts your thinking about as much as staying awake for a day or two. The biggest fix is a steady schedule: same bedtime and wake time every day, within about an hour on weekends. Stop caffeine by mid-afternoon (it can last 8 hours), keep naps to 20 minutes, and keep screens off for the last 30 to 60 minutes. Never drive drowsy. Trouble sleeping most nights is worth a doctor visit; the first treatment usually isn't pills.

What to know

1. Aim for 7 to 9 hours. Adults who sleep less than 7 hours a night may have more health problems. More than 9 isn't necessarily harmful and may help young adults or people catching up on lost sleep.
2. Work backward from your wake time. If you need to be up at 7:30 a.m., lights-out by 11:30 p.m. gets you about 8 hours. Then keep that wake time every day, with weekends within about an hour. Sleeping in late on weekends disrupts your body clock.
3. Use the last hour for quiet time. Skip intense exercise and bright screens; the light can signal your brain that it's time to be awake. The CDC says turn devices off at least 30 minutes before bed.
4. Set up the room: quiet, cool and dark. A dim night light is fine. In a dorm or shared room, an eye mask and earplugs can do the same job.
5. Watch the stimulants. Caffeine can last up to 8 hours, so a late-afternoon coffee can keep you up. It's also in soda, tea and chocolate. Nicotine interferes with sleep too.
6. Skip heavy meals within a few hours of bed, and skip alcohol before bed. A light snack is okay.
7. Get outside and be active during the day when you can.