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Sleep calculatorHow long should you nap?
Nap the right length and you wake up sharp. Nap the wrong length and you wake up groggy. Here's when to set your alarm.
Allowing ~5 minutes to fall asleep, set your alarm for:
instant alertness, no grogginess
deep recovery, wakes clean
☕ Coffee-nap trick: drink a coffee right before a 20-minute nap — caffeine kicks in just as you wake, for a double boost. Check your daily caffeine limit first.
The two nap lengths that work
- 20-minute power nap — you stay in light sleep, so you wake easily with a 2–3 hour alertness boost. Best for a quick recharge.
- 90-minute full cycle — you complete a whole sleep cycle (including deep and REM sleep) and wake at the light stage. Best when you're genuinely sleep-deprived.
The length to avoid: 30–60 minutes
Naps of 30–60 minutes drop you into deep slow-wave sleep but wake you before the cycle finishes. That's sleep inertia — the heavy, groggy feeling that can last 15–30 minutes and leave you worse off than before the nap.
When to nap
The best window is the natural post-lunch dip, around 1–3 pm. Napping after about 4 pm can eat into your night-time sleep drive and make it harder to fall asleep at bedtime.
Nap like a pro
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Frequently asked questions
How long should I nap?
20 minutes for a quick alertness boost, or 90 minutes for full recovery. Avoid 30–60 minutes, which leaves you groggy.
What is a coffee nap?
A coffee right before a 20-minute nap. Caffeine takes ~20 minutes to work, so it arrives as you wake — and the nap clears adenosine, the sleepiness chemical. The combo beats either alone.
Why do I feel worse after a nap?
You probably napped 30–60 minutes and woke from deep sleep — that's sleep inertia. Keep naps to 20 minutes or extend to a full 90.