Nap Calculator
Pick your nap start time and get the perfect alarm. A 20-minute power nap or a 90-minute full cycle — both wake you up without grogginess.
Boosts alertness without entering deep sleep
Completes a full sleep cycle including REM
More rest than a power nap
⚠ Often causes grogginess — you may wake mid-cycle
Power naps (10–20 min) keep you in light sleep — no grogginess on waking. Full cycle naps (90 min) complete all sleep stages including REM. Avoid 30–60 min naps if you need to be alert immediately after.
20-Min Power Nap
Stays in light sleep (stage 1–2). You wake up sharp with no grogginess. Best for a quick midday recharge.
90-Min Full Cycle
Completes light sleep, deep sleep, and REM. Feels like a proper sleep. Best when you have time.
Avoid 30–60 Min
Drops you into deep sleep mid-cycle. Waking here causes sleep inertia — that heavy, disoriented feeling.
Frequently asked questions
How long should a nap be?▾
The two best nap lengths are 20 minutes (power nap) and 90 minutes (full sleep cycle). Avoid 30–60 minutes — you wake mid-cycle feeling groggy.
What is a power nap?▾
A 10–20 minute nap that stays in light sleep. Because you never enter deep sleep, you wake up alert. NASA research found a 26-minute nap improved pilot alertness by 54%.
Why do I feel groggy after a 30-minute nap?▾
At 30 minutes you've entered deep sleep (stage 3) but haven't finished the cycle. Waking mid-cycle causes sleep inertia. Cut to 20 min or extend to 90 min.
What is the best time of day to nap?▾
Between 1 PM and 3 PM — this aligns with the natural post-lunch alertness dip. Avoid napping after 4 PM as it can disrupt night sleep.