Nap Time Calculator
Choose your nap type and find the perfect wake-up time. The right nap length makes all the difference between refreshed and groggy.
10 min
Power Nap
Quick alertness boost, zero grogginess
20 min
NASA Nap ⭐
Scientifically optimal — NASA-proven boost
30 min
Short Nap
Some deep sleep, possible grogginess
60 min
Memory Nap
Deep sleep for memory consolidation
90 min
Full Cycle
Complete sleep cycle, most refreshing
Nap starts—
Fall asleep time—
Nap duration—
Alarm time—
Best nap window: 1:00–3:00 PM aligns with your natural circadian dip and is far enough from bedtime to avoid disrupting nighttime sleep. Avoid napping after 4:00 PM if you sleep at 10–11 PM.
Napping — FAQ
What is the best nap length?
It depends on your goal. 10–20 minutes (power/NASA nap) is best for quick alertness without grogginess — NASA research found a 26-minute nap boosted pilot performance by 34% and alertness by 54%. 90 minutes completes a full sleep cycle and is best if you need deep rest. Avoid 30–60 minute naps if you're sensitive to sleep inertia.
Why do I feel groggy after a nap?
Grogginess after a nap (called sleep inertia) happens when you wake during deep sleep (N3). This typically occurs with 30–60 minute naps. To avoid it, either keep your nap under 25 minutes (before deep sleep begins) or nap for a full 90 minutes to complete the cycle.
Will napping affect my nighttime sleep?
Short naps (under 30 minutes) before 3 PM usually don't affect nighttime sleep. Long naps (60–90 min) or late naps (after 4 PM) can reduce sleep pressure and make it harder to fall asleep at night. If you struggle with insomnia, avoid daytime naps entirely.