小睡多久 午睡时间 能量小睡 20分钟小睡 | nap calculator how long should I nap power nap 20 minutes
Nap Calculator
Enter when you start your nap and find the best wake-up time — a quick power nap or a full cycle, without the grogginess.
When do you start your nap?
We add about 15 minutes of time to fall asleep to every plan.
Your nap plans
How naps work
Sleep runs in cycles of about 90 minutes, moving from light sleep into deep slow-wave sleep and back. A short 10–20 minute nap keeps you in light sleep, so you wake refreshed — research on nap length shows naps of 5–20 minutes restore alertness with minimal grogginess (Brooks & Lack 2006, Sleep Med Rev). Naps of 30–60 minutes drop you into deep sleep, and waking from it causes sleep inertia: that heavy, disoriented feeling. A full 90-minute nap lets you complete a whole cycle and wake during lighter sleep again.
📖 Related reading: The Complete Guide to Napping · Do Power Naps Really Work? · How Long It Should Take to Fall Asleep
Frequently asked questions
How long should a nap be?
For most people 10–20 minutes is ideal: you stay in light sleep and wake refreshed. If you have time for a full cycle, 90 minutes also ends in light sleep. The lengths to avoid are 30–60 minutes.
Why do I feel worse after a 30–60 minute nap?
That duration often drops you into deep slow-wave sleep, and being woken from deep sleep causes sleep inertia — heavy grogginess that can last 30 minutes or more. Either keep it short, or go the full 90 minutes.
What is the best time of day to nap?
The early afternoon, roughly 1–3 p.m., matches your natural circadian dip and is easiest to fall asleep in. Napping after 3 p.m. eats into the sleep pressure you need at night and can push back bedtime.
What is a coffee nap?
Drink a coffee right before a 20-minute nap. Caffeine takes about 20 minutes to start working, so it kicks in just as you wake — a double boost. Our caffeine calculator can help you time the rest of the day.
Disclaimer: This tool is for general informational purposes only and is not medical advice. If you have chronic sleep problems, please consult a healthcare professional.
References
- Waterhouse, J., et al. (2007). Jet lag: trends and coping strategies. The Lancet, 369(9567), 1117–1125.
- Dhand, R., & Sohal, H. (2006). Good sleep, good learning, good life.
- National Sleep Foundation. (n.d.). Napping. sleepfoundation.org.