Pick a power nap, a coffee nap or a full 90-minute cycle and get the alarm time, with the minutes you need to doze off and a check that the nap ends far enough from bedtime.
Is a 90-minute nap good for an adult?
Pick a power nap, a coffee nap or a full 90-minute cycle and get the alarm time, with the minutes you need to doze off and a check that the nap ends far enough from bedtime.
A 90-minute nap is about the length the Sleep Foundation says lets the body cycle through the stages of sleep without interrupting deep sleep. The calculator below is filled in with 90 minutes of sleep, lying down at 1:00 PM and 5 minutes to doze off, which puts the alarm at 2:35 PM. Choose your bedtime to check that the nap starts 8 or more hours before it, as the Sleep Foundation advises, or switch to a 20-minute power nap or a coffee nap and press Calculate.
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Nap length, alarm time and a check against bedtime
Twenty minutes, fifteen with a coffee, or a full ninety: those are the three nap lengths the sleep research keeps coming back to. This nap calculator turns the one you choose into an alarm time, adds the minutes you need to doze off, and checks the start against your bedtime, because a nap that ends too close to the night costs you sleep later.
Setting up a nap in six picks
- Hour, minutes, AM or PM - when you lie down, in five-minute steps.
- Type of nap - power nap (20 minutes of sleep), caffeine nap (15), full-cycle nap (90), or your own length from 5 to 120 minutes.
- Minutes of sleep - only for your own length, decimals allowed.
- Time to doze off - 0 if you want the timer to count from lying down, otherwise 5 to 20 minutes.
- Bedtime tonight - optional, from 8:00 PM to 2:00 AM, plus morning bedtimes for night shifts. With it, the check uses the 8-hour rule instead of the 3 p.m. rule of thumb.
- Read the result - the alarm, the timer, the time you are likely asleep, the gap to bedtime, and the same start run through all three nap types.
Seven naps, seven alarm times
Nap 1: the lunch-break power nap
Situation:1:00 PM / power / 5 minResult: alarm 1:25 PM, asleep about 1:05 PM.
Nap 2: coffee, then a nap before a long drive
Situation:2:00 PM / caffeine / 0 minResult: alarm 2:15 PM; the caffeine is felt around 2:30 PM.
Nap 3: a full cycle on a day off
Situation:1:30 PM / full cycle / 10 min / bedtime 11:00 PMResult: alarm 3:10 PM; the nap starts 9 h 30 min before bed, past the 8 hours advised.
Nap 4: the 45-minute middle ground
Situation:2:00 PM / own length 45 min / 10 minResult: alarm 2:55 PM, with a warning that naps longer than 30 minutes can leave you groggy.
Nap 5: home from work at five
Situation:5:00 PM / power / 5 min / bedtime 10:30 PMResult: alarm 5:25 PM, but only 5 h 30 min before bed; the latest start for 8 hours would have been 2:30 PM.
Nap 6: second shift, late bedtime
Situation:4:30 PM / power / 5 min / bedtime 1:00 AMResult: alarm 4:55 PM, 8 h 30 min before bed, so the check passes even after 3 p.m.
Nap 7: before a night shift
Situation:7:00 PM / full cycle / 10 min / bedtime 8:00 AMResult: alarm 8:40 PM, a 13-hour lead before the morning bedtime.
Three nap lengths and where each one comes from
Each nap type goes back to a source; the NASA row is the study most nap advice quotes.
| Nap | Sleep | What the source says |
|---|---|---|
| Power nap | 20 min | Sleep Foundation: the best adult nap is about 20 minutes and no longer than 30 |
| Caffeine nap | under 15 min | Reyner and Horne: 200 mg caffeine plus a short nap in a 30-minute break cut driving incidents to 9% of placebo, caffeine alone to 34% |
| Caffeine plus a 20-minute nap | 20 min | Hayashi and colleagues: 200 mg before a 12:40 nap was the most effective of five conditions for the hour after waking |
| Full-cycle nap | about 90 min | Sleep Foundation: long enough to cycle through the sleep stages without interrupting deep sleep |
| NASA cockpit rest | about 26 min | Pilots given a 40-minute rest period fell asleep in 5.6 minutes and were more alert than the group without rest |
Latest nap start for each bedtime
The Sleep Foundation advises napping eight or more hours before bedtime. Subtract eight hours from yours and you have the latest start the calculator still marks as fine.
| Bedtime | Latest nap start | Power nap alarm from that start |
|---|---|---|
| 9:00 PM | 1:00 PM | 1:25 PM |
| 10:00 PM | 2:00 PM | 2:25 PM |
| 11:00 PM | 3:00 PM | 3:25 PM |
| 12:00 AM | 4:00 PM | 4:25 PM |
| 1:00 AM | 5:00 PM | 5:25 PM |
| 8:00 AM (night shift) | 12:00 AM | 12:25 AM |
The last column assumes 5 minutes to doze off.
Nap questions people actually type
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See also
Calculator verified by the LiczGrupa.pl team
Content, formulas and results have been reviewed for accuracy and relevance by our team of specialists.
Reviewed by: Natalia Skrzek