Nap length calculator

Choose a short nap or a full sleep cycle and get an alarm time that avoids waking up groggy.

Your details

Lie down at 13:30, asleep after about 10 min

13:50

set your alarm for a 10 minute nap

Time to fall asleep10 min
Nap length10 min
Total time lying down20 min
Groggy at first in the study30 minute naps
Bedtimeadd it to see how long you will be awake before bed

In a sleep lab study, 10 minutes was the most refreshing nap: people felt better straight away, for up to about 2.5 hours.

Needing a nap every day despite a full night in bed is worth mentioning to your GP. See your GP if changing your sleep habits has not helped, you have had trouble sleeping for months, or it is making it hard to cope. If you feel sleepy while driving, stop somewhere safe.

The working

Lying down at 13:30

If you take about 10 minutes to drop off, a 10 minute power nap means setting the alarm for 13:50: 20 minutes on the sofa in total. In a sleep lab study of nap lengths after a short night, the 10 minute nap gave the quickest and longest lasting lift, up to about two and a half hours.

Which nap?

What the study found

Nap	What happens
5 min	little benefit
10 min	feel better straight away, for up to about 2.5 hours
20 min	helps, but takes about half an hour to kick in
30 min	groggy at first, better later
90 min	not tested in this study

Napping well

Small things

If naps leave you awake at night, try napping earlier or skipping them
Set an alarm so a short nap stays short
If you have insomnia, the NHS advice is to skip daytime naps altogether

Coffee naps and bedtime

Two optional extras

Tick coffee nap and the page times a drink for just before you lie down. In a small Japanese study (Hayashi 2003), caffeine taken right before a 20 minute nap left people more alert afterwards than the nap on its own. It suits short naps; skip it later in the day, in pregnancy, or if caffeine affects your sleep.

Add your bedtime and the page shows how long you will be awake between the nap and bed, so you can see at a glance whether a late nap might eat into tonight.

Read with care

What this cannot tell you

Know your sleep cyclesCycles vary from person to person and night to night.
Replace night sleepNaps help, but they are not a fix for regularly short nights.
Make driving safe when tiredIf you are sleepy at the wheel, stop somewhere safe.

Questions

Common questions

How long should a power nap be?

About 10 minutes of sleep. In a sleep lab study it gave the quickest boost, lasting up to about 2.5 hours.

Why do I feel worse after a nap?

That grogginess is called sleep inertia. In the sleep lab study, a 30 minute nap left people groggy at first before they improved, while a 10 minute nap did not.

Does napping affect night sleep?

It can for some people. If you are lying awake at night, try napping earlier or not at all; the NHS insomnia advice is to avoid daytime naps.

Should I nap if I have insomnia?

The NHS advises people with insomnia not to nap during the day, so the tiredness builds towards bedtime.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

If you need naps every day

Needing a nap every day despite a full night in bed is worth mentioning to your GP, as is loud snoring with pauses in breathing. If you feel sleepy while driving, stop somewhere safe.