How Long Should a Nap Be?

For a quick boost in alertness, a short nap of about 10 to 20 minutes in the early afternoon works best for most adults. Longer naps reach deeper sleep, so waking from them often brings a period of grogginess, and late or long naps can make it harder to sleep at night.

This article is general information, not medical advice.

What the Evidence Shows

• A head-to-head trial. Brooks and Lack restricted young adults’ night sleep, then compared afternoon naps of 5, 10, 20, and 30 minutes with no nap. The 5-minute nap did little. The 10-minute nap improved alertness, sleepiness, and performance straight away, with some benefits lasting about two and a half hours. The 20-minute nap’s benefits took about half an hour to appear, and the 30-minute nap was followed by a period of impaired alertness before its benefits came.
• A review. In their review of napping in healthy adults, Milner and Cote concluded that naps can improve alertness, mood, and performance, and that the best length depends on timing, how much sleep you’ve lost, and what you need the nap for. Longer naps can help after a lot of lost sleep, at the cost of grogginess on waking.

The grogginess after a long nap is called sleep inertia: waking from deep sleep leaves the brain slow to come back up to speed.

Making Naps Work

• Keep it short. Set an alarm for 20 to 25 minutes, allowing a few minutes to fall asleep.
• Nap early in the afternoon, during the natural dip in alertness after lunch, and well before evening.
• Don’t nap to make up for a poor routine. If you need naps every day, check how much and how regularly you sleep at night; see How Much Sleep Do Adults Need?

Persistent daytime sleepiness despite enough sleep at night is worth raising with a doctor.

Following It in Kaizora

Naps imported from your watch or ring, or logged by hand, are sleeps like any other: each gets its own Total Sleep Time, and the AASM’s 7-hour default range on Total Sleep Time judges the average of the 7 days ending each day, naps included. The Sleep Regularity Index and Kaizora Sleep Score include naps too. Rate your alertness on the Karolinska Sleepiness Scale before and after a nap to see what it does for you; see What Is the Karolinska Sleepiness Scale?

The Short Version

• A 10- to 20-minute nap in the early afternoon boosts alertness with little grogginess.
• Naps of 30 minutes or more bring sleep inertia, and late naps can disturb the night.
• If you need naps every day, look at your night’s sleep first.

Sources

• Brooks A, Lack L, “A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative?” Sleep 29, no. 6 (2006): 831–840. doi:10.1093/sleep/29.6.831
• Milner CE, Cote KA, “Benefits of napping in healthy adults: impact of nap length, time of day, age, and experience with napping,” Journal of Sleep Research 18, no. 2 (2009): 272–281. doi:10.1111/j.1365-2869.2008.00718.x