Nap calculator: power nap or full cycle
Two alarm times for your nap: a short power nap or one full cycle, and the stretch in between to avoid.
Lying down at 1:30 PM, set an alarm for:
- 2:00 PM14:00Power nap · 20 min asleep, 30 min in total
- 3:10 PM15:10Full cycle · about 90 min asleep, 1 h 40 min in total
Try not to sleep through the shaded stretch (about 30–60 minutes asleep): around 45 minutes is the length the National Sleep Foundation calls problematic, because you are more likely to wake from deep sleep and feel groggy.
How the math works
The power-nap alarm is the time you lie down plus the minutes you need to fall asleep plus 20 minutes. The National Sleep Foundation says "a 20 minute nap is the best length," and the CDC's National Institute for Occupational Safety and Health (NIOSH) recommends a brief nap under 20 minutes with an alarm set for 15 to 30 minutes.
The full-cycle alarm adds 90 minutes of sleep instead. NIOSH explains that waking after about 90 minutes, "predicted to be the end of a sleep cycle," may mean less grogginess that clears faster, and the National Sleep Foundation says 60 to 90 minutes is enough time for deep, slow-wave sleep.
The shaded zone marks 30 to 60 minutes of sleep. The National Sleep Foundation warns that "medium-length naps of around 45 minutes can be problematic," and NIOSH notes that sleep reaches deep stages at about an hour, so waking there can bring sleep inertia, the groggy feeling after waking.
The 10-minute default for falling asleep is only a starting point. Change it to what is true for you.
General information based on published averages, not medical advice. Sleep cycles and needs vary from person to person. If you have problems sleeping or feel unusually tired during the day, see a doctor.