# How long should a power nap be? 10, 20 or 90 minutes Source: https://spolvero.design/articles/how-long-should-a-power-nap-be/ Updated: 2026-09-24 Tool: https://spolvero.design/tools/timers/countdown-timer/20-minute-timer/ > A power nap should last ten to twenty minutes. That is long enough to feel rested and short enough to wake before deep sleep, which is what makes longer naps leave people groggy. If you have time for more, a full sleep cycle of about 90 minutes also wakes well. Nap in the early afternoon, add five minutes to fall asleep, and set an alarm that keeps ringing until you get up. A good nap and a bad nap can be the same person on the same sofa. The difference is almost always the length. Wake at the right point and you feel sharper. Wake at the wrong one and you feel worse than before you lay down. ## The short answer: ten to twenty minutes | Nap length | What happens | How you wake | | --- | --- | --- | | 10 minutes | Light sleep only | Alert, with little grogginess | | 20 minutes | Light sleep, near its end | Alert; the classic power nap | | 30 to 60 minutes | Often reaches deep sleep | Groggy for a while | | About 90 minutes | One full sleep cycle | Usually wakes well, but it is a long nap | Ten to twenty minutes is the range most sleep advice gives, and it is the one to use for a nap in the middle of a working day. ## Why longer naps leave you groggy Sleep runs in cycles. You fall into light sleep first, then deeper, slow-wave sleep, then lighter sleep and dreaming, and the whole cycle takes around 90 minutes. Waking from light sleep is easy. Waking from deep sleep is not. The heavy, confused feeling after a long nap has a name, sleep inertia, and it can take up to half an hour to clear. It is why a 45-minute nap so often feels like a mistake: it ends right in the deep part of the cycle. A short nap stops before deep sleep begins. A 90-minute nap goes all the way round and ends in lighter sleep again. The awkward lengths are the ones in between. ## What a short nap does The best-known evidence comes from NASA. In a 1995 study of long-haul pilots, crews given a 40-minute rest opportunity slept for about 26 minutes on average, and their performance on reaction tests improved by 34% compared with pilots who did not nap. Their measured alertness improved by 54%. A nap does not replace a night's sleep. It helps with the afternoon slump, a long drive, or a late shift, and it helps most when you are already short of sleep. ## How to take one 1. **Pick the early afternoon.** Most people have a natural dip in alertness after lunch. Napping after about 3 pm makes it harder for many to fall asleep at night. 2. **Allow time to fall asleep.** The twenty minutes are for sleep, and most people take a few minutes to drift off. Set 25 minutes rather than 20. 3. **Make it dark and quiet.** An eye mask or a darkened room shortens the drift-off time more than anything else. 4. **Set an alarm you cannot sleep through.** A single soft chime is easy to miss when you are asleep. For the alarm, open the [20 minute timer](/tools/timers/countdown-timer/20-minute-timer/) and choose **Loud bell, until stopped** in the sound menu. At zero it rings every three seconds until you press a key or tap the screen, and it gives up by itself after two minutes. Press **Play the alarm now** first and turn the volume up until it would wake you. The alarm is set on your computer's audio clock the moment you press Start, so it rings on time even if the timer is in a background tab. On a phone, keep the screen on: a locked phone may pause the sound. ## When a 90-minute nap makes sense A full cycle is worth it when you are about to lose a night's sleep: before a night shift, a late drive, or an overnight flight. It usually ends in lighter sleep, so waking is easier than after 45 minutes. It costs most of an afternoon, though, and it is more likely to make falling asleep that night harder. For an ordinary tired afternoon, stick to twenty minutes. The [1 hour timer](/tools/timers/countdown-timer/1-hour-timer/) has a 90 minute preset if you need one. ## The coffee nap Some people drink a coffee straight before a short nap. Caffeine takes a while to take effect, so the idea is that it starts working about when the nap ends. Research on sleepy drivers has found the combination works better than either alone, but if caffeine keeps you awake, the nap will not happen at all. Try it only early in the day. ## If you cannot fall asleep Lying still with your eyes closed for fifteen minutes still rests you, even without sleep. Do not stay longer to make up for it. If you nap every day and still feel exhausted, that is worth mentioning to a doctor, because it can be a sign of poor sleep at night. ## Related For shorter resets during the day, see [how long a brain break should be](/articles/how-long-should-a-brain-break-be/). The [10 minute timer](/tools/timers/countdown-timer/10-minute-timer/) suits the shortest naps, and the [countdown timer](/tools/timers/countdown-timer/) sets any length you like. If the afternoon calls for a cup of tea instead, the guide to [how long to steep tea](/articles/how-long-to-steep-tea/) has the times. ## Questions ### How long should a power nap be? Ten to twenty minutes. That is enough to feel rested, and short enough to wake before deep sleep, so you do not come round groggy. ### Why do I feel worse after a long nap? A nap of 30 to 60 minutes often ends in deep sleep, and waking from deep sleep brings sleep inertia: grogginess and slow thinking that can last up to half an hour. ### Is a 90-minute nap better than a 20-minute one? It does something different. About 90 minutes is one full sleep cycle, so it usually ends in light sleep and wakes well, but it takes most of an afternoon and can make night sleep harder. ### What is the best time of day to nap? Early afternoon, during the natural dip in alertness after lunch. Napping after about 3 pm makes it harder for many people to fall asleep at night.