Nap calculator and power nap timer
How long should a nap be? Pick the kind of nap you want, see where it ends in your sleep stages, then start the timer — it rings with a gentle tone when time's up.
Choose your nap
You'd wake in: Stage N2 (light)
Light sleep at the alarm: you should feel alert again within a few minutes.
Nap timer
25:00
Ready when you are.
Includes your 5 minutes to fall asleep. Keep this tab open and your volume up; your phone may pause timers in background tabs, so a phone alarm is a good backup.
How long should a nap be?
10–20 minutes is the classic power nap. You stay in light N1/N2 sleep, so you wake quickly and alertness improves within minutes. In a well-known study by Brooks and Lack (2006, Sleep), a 10-minute nap improved alertness and performance almost immediately, while 20- and 30-minute naps took longer to pay off because of grogginess.
30–60 minutes is the awkward zone: long enough to reach deep sleep, not long enough to come back out. Expect sleep inertia — heavy, foggy grogginess that can last 30 minutes or more.
About 90 minutes covers a full cycle including REM. You wake from lighter sleep, but it's a big block of time and can make it harder to fall asleep at night.
Best time to nap
The natural afternoon dip in alertness usually falls around 1–3 pm, roughly seven to nine hours after you wake. Napping later than about 3 pm eats into the sleep pressure you need for bedtime.
The coffee nap
Drinking a cup of coffee right before a 15–20 minute nap is a trick with some research behind it: caffeine takes around 20 minutes to kick in, just as you wake. Check it won't clash with bedtime in the caffeine cutoff calculator.
Questions people ask
How long should a power nap be?
10 to 20 minutes. That keeps you in light sleep so you wake alert. Add a few minutes for falling asleep when you set the timer.
Is a 15 minute power nap enough?
Yes. Studies of brief afternoon naps, including Brooks & Lack (2006), found 10–15 minute naps improve alertness for one to three hours with little grogginess.
Why do I feel worse after a nap?
You probably woke from deep (N3) sleep. That causes sleep inertia, which can last 30 minutes or longer. Keep naps under about 25 minutes or extend to a full 90-minute cycle.
Is a 90-minute nap good?
It lets you complete a full cycle and wake from lighter sleep, which helps if you are seriously sleep-deprived. It may make it harder to fall asleep that night, so keep it early in the afternoon.
Does the timer work with my screen off?
It uses real clock time, so it stays accurate, but some phones pause audio in background tabs. Keep the page open with the screen on low, or set a phone alarm as a backup.