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The short answer For most adults, 10 to 20 minutes is the sweet spot: long enough to feel sharper, short enough to wake up without grogginess. If you have time and are short on sleep, a full-cycle nap of about 90 minutes is the other good option. Avoid 30 to 60 minutes, and nap in the early afternoon so it doesn’t steal from tonight.
Nap length decides which stage of sleep you wake up from, and that’s what decides how you feel afterward. Here’s the quick version.
| Nap length | What you get | The catch | Best for |
|---|---|---|---|
| 5 minutes | Very little | Too short to help much in testing | Not worth setting an alarm for |
| 10 to 20 minutes (power nap) | Quick boost in alertness and performance | Hard to fall asleep fast if you’re not tired | Afternoon slump, before a drive or a meeting |
| 30 to 60 minutes | Benefits eventually, after a groggy stretch | Waking from deep sleep: sleep inertia | Usually the length to avoid |
| About 90 minutes (full cycle) | A complete sleep cycle, including deep and REM sleep | Takes a big chunk of the day; can make bedtime later | Real sleep debt, before a night shift |
How to take a power nap
- Pick an early-afternoon slot. Aim for at least 7 or 8 hours before your bedtime. For an 11 pm bedtime, that’s before about 3 pm.
- Set an alarm for 20 to 25 minutes. The extra few minutes cover the time it takes to drift off. If you fall asleep quickly, set it for 20.
- Make it dark and quiet enough. A sleep mask, earplugs or a dim room helps. Lying flat isn’t required; a reclined chair works.
- Don’t worry if you don’t fully sleep. Lying still with your eyes closed is still rest. Don’t extend the alarm to “make up” for it.
- Get up when the alarm goes off. Snoozing is how a 20-minute nap turns into a groggy 45-minute one.
- Give yourself a few minutes before anything critical. Bright light or splashing water on your face can speed up the wake-up.
Why 10 to 20 minutes works best
The cleanest test of nap length comes from a 2006 study at Flinders University in Australia. Twenty-four healthy young adults slept about five hours at night, then took afternoon naps of exactly 5, 10, 20 or 30 minutes, or no nap.
- The 5-minute nap did little.
- The 10-minute nap improved every measure right away, including sleepiness, fatigue and mental performance, with some benefits lasting about two and a half hours.
- The 20-minute nap helped too, but the benefits took about 35 minutes to appear.
- The 30-minute nap caused a period of impaired alertness and performance right after waking, then improvements later.
The authors concluded that 10 minutes was the most effective length they tested. A review of napping research reached a similar conclusion: naps under 30 minutes promote wakefulness and improve performance and learning, while longer naps bring grogginess.
For people who need a few minutes to fall asleep, a 20-minute alarm lands you near that 10-to-20-minute window of actual sleep.
The NASA pilot nap
The “NASA nap” you’ll see quoted comes from a 1994 NASA study of long-haul flight crews. Pilots were allowed a planned 40-minute rest in the cockpit seat. They fell asleep on 93% of opportunities and slept an average of about 26 minutes, and the benefits showed up through the descent and landing phases of flight. The nap didn’t affect their sleep on layovers.
Why 30 to 60 minutes can leave you groggy
That heavy, confused feeling after a longer nap is called sleep inertia. It happens when you wake up from deep sleep. NIOSH, the CDC’s workplace safety institute, says it typically lasts 30 to 60 minutes and has been observed lasting up to two hours, though it usually fades within 30 minutes unless you’re sleep deprived.
Sleep deprivation makes it worse in another way too. If you start a nap very tired, NIOSH notes, your brain can reach deep sleep more quickly, so even a moderately short nap can leave you foggy. That’s the irony: the people who most need a nap are the ones most likely to wake up groggy from it.
Don’t drive or do anything safety-critical straight after a nap, especially a long one or one taken while very tired. Give yourself at least 15 to 30 minutes to fully wake up.
The 90-minute nap
A full sleep cycle runs about 80 to 100 minutes, according to the National Heart, Lung, and Blood Institute. Wake up at the end of one and you’re coming out of lighter sleep, not deep sleep. NIOSH’s guidance says waking after either about 20 minutes or about 90 minutes may leave less grogginess, and what grogginess there is should clear within 15 to 30 minutes.
Cycle length varies, so 90 minutes is an estimate. The sleep calculator uses the same cycle math for nights, and our guide to sleep stages explains what happens inside each cycle.
A long nap makes most sense when you’re carrying real sleep debt or facing a long night. NIOSH describes a study in which nurses who took a 1.5-hour nap before their first night shift felt more alert during the second half of that shift.
What’s the best time of day to nap?
Early to mid-afternoon, which lines up with the natural post-lunch dip in alertness. The bigger rule is distance from bedtime. Napping late makes it harder to fall asleep at night, because a nap releases some of the sleep pressure that builds up through the day. The Sleep Foundation notes experts typically suggest napping eight or more hours before bedtime.
Night shift workers are the exception. Their “afternoon” is whenever the schedule allows, and NIOSH notes a short nap during a night shift can help, as long as there’s time to shake off grogginess before critical work.
What about a coffee nap?
A coffee nap means drinking coffee right before a short nap, so the caffeine starts working as you wake up. In a small Japanese study of 10 young adults, a 20-minute nap after 200 mg of caffeine beat a nap alone for sleepiness and performance over the following hour. Bright light right after waking came close.
It’s a tiny study, and the trade-off is caffeine in your system for hours afterward. Keep coffee naps to early afternoon. Our guide to how long caffeine stays in your system shows why a 4 pm coffee nap can cost you sleep at night.
Is napping bad for you?
A short, planned nap isn’t. Long, frequent naps are a different story. The napping review above notes that frequent, long naps may be associated with higher illness and death rates, especially in older adults. Those are associations: long naps may be a sign of poor night sleep or an underlying illness rather than a cause.
Two situations call for caution:
- You have trouble sleeping at night. Naps eat into the sleep pressure you need at bedtime. Cleveland Clinic’s insomnia advice includes avoiding naps during the day, at least while you’re working on your night sleep.
- You need naps every day despite enough night sleep. That’s worth looking into rather than working around.
When to see a doctor
- If you’re sleepy enough to nap most days even after 7 or more hours of sleep, or you nod off during conversations, meals or driving, talk to a doctor. Excessive daytime sleepiness can be a sign of sleep apnea or another sleep disorder.
- Loud snoring with gasping or pauses in breathing also needs a sleep apnea evaluation.
- If you’re drowsy behind the wheel, pull over somewhere safe. A short nap there is reasonable; then let the grogginess pass before you drive on.
Napping is a patch for short nights, not a substitute for them. To see how much sleep you actually need at night, check how much sleep you need by age, and browse more in Sleep Science.
Common questions
Is a 20 or 30 minute nap better?
Twenty minutes is usually better. In a sleep-lab comparison, a 30-minute nap caused a stretch of grogginess and worse performance right after waking, while 10 and 20-minute naps didn't.
Is a 2 hour nap too long?
For most people, yes. Long naps can leave you groggy and make it harder to sleep at night. Exceptions include shift workers napping before a night shift. Needing long naps often is worth raising with a doctor.
What time should I stop napping?
Aim to finish napping at least 7 to 8 hours before bedtime, which for most people means before about 3 pm.
Why do I feel worse after a nap?
That's sleep inertia, the grogginess of waking from deep sleep. It usually fades within 30 minutes but can last longer if you're sleep deprived. Shorter naps make it less likely.
Written and checked by the Sleep Brief editors. We base every article on published research and guidance from medical bodies, and link the sources inline. How we research.
This article is for general education and isn't medical advice. If poor sleep lasts more than a few weeks, or you snore loudly, stop breathing in your sleep or feel sleepy while driving, talk to a doctor.
