Sleep cycle bedtime calculator
Enter your wake time to get suggested bedtimes for 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 wake-up time, 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
Bedtime = wake time - (cycles × cycle length) - time to fall asleep. Defaults are 90 minute cycles and 15 minutes to fall asleep; the main result is for five cycles.
Example
Inputs: Wake-up time = 07:00, Time to fall asleep = 15 min, Cycle length = 90 min. Result: Go to bed at (5 cycles): 23:15.
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
How many cycles do I need?
Adults need 7 hours of sleep or more, which is about 5 cycles (7.5 hours) or 6 cycles (9 hours).
Why wake at the end of a cycle?
Waking from light sleep at the end of a cycle is usually easier than waking from deep sleep, so you feel less groggy.
What is time to fall asleep?
How long you take to drift off after lying down, usually 10 to 20 minutes. Adjust it to your habit.