Nap timing tool
Nap smart, wake up refreshed.
Set an alarm for your nap and get a wake-up time that avoids the groggy middle of deep sleep — a 20-minute power nap or a full 90-minute cycle.
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Based on your chosen start time
Why some naps refresh and others wreck you
A nap is a small bet on sleep stages. In the first 10–20 minutes, you stay in light sleep, which is easy to wake from — that's the classic power nap. Push to 30–60 minutes and you sink into deep slow-wave sleep, where waking up triggers sleep inertia: that heavy, foggy, worse-than-before feeling that can take half an hour to shake off.
The way around it is simple: nap for either 20 minutes or a full 90 minutes. Ninety minutes completes one full sleep cycle, so you wake during light sleep at the cycle's end. This calculator does that math for you — it reads your available time and start time, then sets the alarm at the sweet spot and shows you the exact wake-up time.
The afternoon dip is real
Alertness naturally dips in the early afternoon, roughly between 1 PM and 3 PM, which is why naps taken then feel easiest and most restorative. Napping much later — after about 4 PM — borrows sleep pressure from the night and can push your bedtime later, which is a bad trade if you already struggle to fall asleep.
Two pro moves
The coffee nap is well supported by research: drink a coffee right before a 20-minute nap. Caffeine takes about 20 minutes to kick in, so you wake as it starts working — studies find the combination beats either one alone. And keep naps dark and cool when you can; even a sleep mask and earplugs meaningfully deepen a short nap.
When to skip the long nap
If you have insomnia, long daytime naps can make nights worse by reducing the sleep drive you need at bedtime. In that case, keep any nap under 20 minutes and before mid-afternoon — or skip napping and protect the night instead.
This calculator is a planning estimate, not medical advice. Nap needs vary, and persistent daytime sleepiness despite good nights can be a sign of a sleep disorder worth discussing with a healthcare professional.
Nap questions
How long should a nap be?
The two safest options are a 20-minute power nap, which ends before deep sleep begins, or a full 90-minute nap, which completes one sleep cycle. Naps of 30–60 minutes often wake you from deep sleep and cause grogginess.
Why do I feel worse after a nap?
Waking from deep slow-wave sleep triggers sleep inertia — a heavy, foggy feeling that can linger 30 minutes. It usually happens with 30–60 minute naps: long enough to reach deep sleep, too short to finish the cycle.
What is the best time of day to nap?
Early afternoon, roughly 1 PM to 3 PM, matches the natural dip in alertness. Napping after about 4 PM can make it harder to fall asleep at night.
Do power naps actually work?
Research shows a 10–20 minute nap can improve alertness, mood, and performance for a few hours. Staying under 20 minutes keeps you in light sleep so you wake easily.
Will a nap ruin my nighttime sleep?
A short nap before mid-afternoon usually leaves the night untouched. Long or late naps reduce sleep pressure and can push bedtime later. If you have insomnia, keep any nap short.