Wake-up time calculator (sleep cycles)
Enter the time you go to bed to get alarm times that match the end of three to six sleep cycles.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter bedtime, time to fall asleep and cycle length.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Wake time = bedtime + time to fall asleep + (cycles × cycle length). Defaults are 90 minute cycles and 15 minutes to fall asleep; the main result is for five cycles.
Example
Inputs: Bedtime = 23:00, Time to fall asleep = 15 min, Cycle length = 90 min. Result: Wake up at (5 cycles): 06:45.
Limits and caveats
- A 90 minute cycle is an average; real cycles run about 70 to 120 minutes and change through the night.
- The tool does not diagnose insomnia or other sleep disorders.
Questions about this tool
If I sleep now, when should I wake?
Enter the current time, then pick a time from the table that gives you 5 or 6 cycles if you can.
Are 3 cycles enough?
Three cycles are only 4.5 hours, below the 7 hours adults need, so do not make it a habit.
Why add time to fall asleep?
The first cycle does not start when you lie down, only once you actually fall asleep.