Sleep schedule
Nap Timing Calculator
Many people feel a dip in alertness in the early afternoon. Mayo Clinic and the Sleep Foundation suggest napping in the early afternoon, around 2 or 3 p.m. at the latest, and keeping naps to about 20 minutes so you wake from light sleep and protect your night sleep. This tool estimates a nap window based on your wake time and when to set the alarm.
How it works
Window opens 6 hours after waking and closes 8 hours after waking. For someone who wakes at 7:00 AM this gives 1:00 PM to 3:00 PM, which matches the early afternoon timing these sources recommend. Alarm = lie down time + minutes to fall asleep + nap length.
Example
Wake at 7:00 AM: window 1:00 PM to 3:00 PM. Lying down at 1:00 PM for a short nap with 10 minutes to fall asleep: alarm at 1:30 PM.
Assumptions and limits
- The 6 to 8 hour offset is a simple rule of thumb anchored to the usual early afternoon advice, not a measured personal body clock.
- Naps longer than about 20 to 30 minutes can bring grogginess (sleep inertia) on waking, and late or long naps can make it harder to fall asleep at night.
- If you have insomnia, avoiding naps is often recommended.
- Needing to nap every day despite enough night sleep can be a sign of a sleep disorder.
Frequently asked questions
How long should a nap be?
Mayo Clinic suggests about 10 to 20 minutes. A longer nap is more likely to include deep sleep and leave you groggy.
Is a 90 minute nap ever useful?
A full cycle nap can help when you are very short on sleep, such as before a night shift. It is more likely to affect night sleep, so keep it well before your usual bedtime.
Should I nap if I have insomnia?
Naps reduce the sleep pressure you build during the day, which can make it harder to fall asleep at night. Insomnia treatment programs usually advise avoiding or limiting naps.
Sources
Tools and screening scores are general information. They cannot diagnose or rule out a sleep disorder. Read our medical disclaimer.