Body · Sleep basics

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.

Easy10 min to read; 2 weeks to reset a scheduleFreeChecked October 2, 2026

What to know

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. Source: NHLBI
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. Source: NHLBI
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. Source: NHLBI The CDC says turn devices off at least 30 minutes before bed. Source: CDC
Set up the room: quiet, cool and dark. A dim night light is fine. Source: NHLBI In a dorm or shared room, an eye mask and earplugs can do the same job.
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. Source: NHLBI
Skip heavy meals within a few hours of bed, and skip alcohol before bed. A light snack is okay. Source: NHLBI
Get outside and be active during the day when you can. Source: NHLBI

Watch out Don't drive drowsy. Drowsy-driving crashes happen most often between midnight and 6 a.m. or in the late afternoon, and often involve a lone driver running off the road at high speed without braking. Source: NHTSA Lack of sleep can also cause microsleep, brief moments of sleep you can't control or notice. If you've ever driven somewhere and not remembered part of the trip, that may have been it. Source: NHLBI

Are you short on sleep?

You often feel like you could doze off while reading or watching TV. Source: NHLBI
...or sitting still in a class, meeting or movie. Source: NHLBI
...or riding in a car for an hour, or sitting in traffic for a few minutes. Source: NHLBI
...or sitting quietly after lunch, or talking to someone. Source: NHLBI
You wake up not feeling refreshed, or wake up repeatedly during the night. Source: NHLBI CDC

What short sleep does

From the National Heart, Lung, and Blood Institute. Source: NHLBI

Area	Effect
School and work	Slower reactions, more mistakes, trouble focusing, remembering and solving problems. You may miss parts of a lecture without realizing it.
Mood	Harder to control emotions and cope with change. Linked to depression and risk-taking.
Appetite	The hunger hormone goes up and the fullness hormone goes down, so you feel hungrier.
Getting sick	You may have more trouble fighting common infections.
Long term	Higher risk of heart disease, high blood pressure, obesity, diabetes and stroke.

Sleep diary: write down each day

When you went to bed Source: CDC
When you woke up during the night
When you woke up in the morning
Naps
Exercise
Alcohol and caffeine
Medications

If it doesn't work

Can't fall asleep at night? Limit naps, or take them earlier in the afternoon, and keep them to 20 minutes. Source: NHLBI
Lying awake? One part of standard insomnia treatment is going to bed only when sleepy, getting out of bed if you can't sleep, and using your bed only for sleep. Source: NHLBI
Working nights or rotating shifts? Keep lights bright at work, limit caffeine to the first part of your shift, use light-blocking curtains, and limit shift changes when you can. Source: NHLBI
Still struggling for weeks, or sleepy even after enough sleep? Talk to a doctor; it could be a sleep disorder like insomnia or sleep apnea. Bring your sleep diary. Source: CDC For long-term insomnia, the usual first treatment is CBT-I, a 6- to 8-week program you can do in person, by phone or online. Source: NHLBI

Good to know

Sleep debt adds up fast

After several nights of losing even 1 to 2 hours a night, your ability to function suffers as if you hadn't slept at all for a day or two. People who are short on sleep often don't realize it. Source: NHLBI

You're not alone

In 2022, between 30% and 46% of adults in each state weren't getting at least 7 hours. Source: CDC

Sleep helps you learn

While you sleep, your brain forms new pathways that help you learn and remember. A good night's sleep improves problem-solving. Source: NHLBI

Sources

National Heart, Lung, and Blood Institute How much sleep is enough?
National Heart, Lung, and Blood Institute Healthy sleep habits
National Heart, Lung, and Blood Institute How sleep affects your health
National Heart, Lung, and Blood Institute Insomnia treatment
Centers for Disease Control and Prevention About sleep
Centers for Disease Control and Prevention Sleep in adults: facts and stats
National Highway Traffic Safety Administration Drowsy driving

Lesson B1.1 · Last checked October 2, 2026 against the sources listed.

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