Sleep Cycle Timer
Bedtimes and wake times that land between cycles.
About Sleep Cycle Timer
Sleep Cycle Timer works backwards or forwards in 90-minute cycles, plus about 14 minutes to fall asleep, to suggest bedtimes or wake times that land between cycles rather than in the middle of deep sleep. Waking mid-cycle is what causes that groggy feeling even after a long night.
How to use it
- Choose whether you are setting a wake-up time or going to sleep now.
- Enter the time.
- Pick one of the suggested times — the first is the recommended six cycles.
Questions
Are sleep cycles really 90 minutes?
On average, but real cycles vary between about 70 and 110 minutes and change through the night. Treat these as targets rather than precise times.
How many cycles do I need?
Five or six, so 7.5 to 9 hours. Four (6 hours) is a workable minimum occasionally, not as a habit.
Is it better to wake mid-cycle or sleep less?
Generally better to complete a cycle, but not at the cost of losing a lot of total sleep. Total duration matters more than cycle alignment.
Sleep Cycle Timer is free and runs entirely in your browser. No account, no upload, no watermark, no limit on use.