lullableIf you are in bed at 1:30 AM and asleep about 15 minutes later, set the alarm for 9:15 AM. That is five 90-minute cycles, or 7.5 hours of sleep. Six cycles end at 10:45 AM, four at 7:45 AM and three at 6:15 AM.
Tonight’s sample
To catch the 9:15 AM window, put your phone face down by 1:30 AM.
Trying to force your brain to empty at midnight feels like homework. Give it something peaceful to ponder instead — with the ending given away in the first line.
Press play, and settle. There is nothing to follow and nothing to finish.
The whole story is 33 minutes. In the app it plays with the screen off and fades to silence on its own.
Get the appFree to download, with a full story free to listen to.
How this calculator works
Sleep is not one long flat stretch. It moves through lighter and deeper stages in a loop, and one pass through the loop is a sleep cycle. On average a cycle takes about 90 minutes, so a night is usually four to six of them.
Being woken from the deep part of a cycle tends to feel heavier than waking near the end of one. So this calculator counts in whole cycles: a wake-up time, minus 90 minutes for each cycle, minus the time you take to fall asleep, is the time to be in bed. In the other direction, the time you get into bed, plus the time to fall asleep, plus 90 minutes for each cycle, is the time to set the alarm.
It is a rule of thumb. Real cycles are not exactly 90 minutes and yours are not the same as anyone else’s, so read the times as a place to start.
Common questions
If I go to sleep at 1:30 AM, what time should I wake up?
If you are in bed at 1:30 AM and asleep about 15 minutes later, set the alarm for 9:15 AM. That is five 90-minute cycles, or 7.5 hours of sleep. Six cycles end at 10:45 AM, four at 7:45 AM and three at 6:15 AM.
Is a sleep cycle really 90 minutes?
Ninety minutes is an average and not a rule. Cycles commonly run from about 70 to 120 minutes, they differ from person to person, and they change across a single night. Treat these times as a starting point and move them fifteen minutes either way until they suit you.
How many sleep cycles do I need?
The American Academy of Sleep Medicine and the Sleep Research Society recommend seven or more hours a night for adults, which is why five cycles, 7.5 hours, is the highlighted option. Six cycles is nine hours. Four and three are for the nights when the alarm is not negotiable.
Why does the calculator add time to fall asleep?
Because nobody is asleep the moment the light goes out. Ten to twenty minutes is common for adults. If your mind keeps working after dark, choose 40 minutes and the bedtime moves earlier to cover it.
Does this measure or track my sleep?
No. It is arithmetic on averages. It does not track, score or measure anything, and it is not a medical device. If poor sleep is persistent, a doctor is the right person to ask.
Wake-up times
- 4:30 AM
- 4:45 AM
- 5:00 AM
- 5:15 AM
- 5:30 AM
- 5:45 AM
- 6:00 AM
- 6:15 AM
- 6:30 AM
- 6:45 AM
- 7:00 AM
- 7:15 AM
- 7:30 AM
- 7:45 AM
- 8:00 AM
- 8:15 AM
- 8:30 AM
- 8:45 AM
- 9:00 AM
- 9:15 AM
- 9:30 AM
- 9:45 AM
- 10:00 AM
- 10:15 AM
- 10:30 AM
- 10:45 AM
- 11:00 AM