Find the best bedtimes for your wake-up time — or the best wake times for your bedtime — using 90-minute sleep cycles.
recommended bedtime (6 cycles)
How to use this tool
Pick whether you know your wake-up time or your bedtime.
Set the time you must wake up, or the time you plan to go to bed.
The default is 15 minutes to fall asleep — change it under Advanced options if you usually take longer.
Choose a bedtime or wake time that completes whole 90-minute cycles, so you wake at a light-sleep boundary.
Formula & worked example
To wake at 07:00 with 15 minutes to fall asleep: 6 cycles → bed at 21:45, 5 cycles → 23:15, 4 cycles → 00:45. Going to bed at 23:00 gives a 6-cycle wake time of 08:15.
Limitations — read this before you rely on it
Sleep cycles average about 90 minutes but vary between people and across the night, and this calculator cannot account for sleep disorders, shift work, caffeine, or age-related sleep changes. It is a planning aid, not medical advice — see a clinician for persistent sleep problems.
Frequently asked questions
It counts back (or forward) in 90-minute sleep cycles from your wake time or bedtime, adding time to fall asleep, so you wake at the end of a cycle rather than mid-deep-sleep.
Most adults need 5–6 cycles (7.5–9 hours of sleep). 6 cycles is the recommended default here.
You are not asleep the moment you get into bed. The default 15 minutes accounts for that gap; adjust it if you usually take longer.
Many people feel groggier when woken from deep sleep than from light sleep at a cycle boundary, though total sleep time matters most.
Cycle timing alone will not fix those. Keep regular hours where possible and talk to a clinician if poor sleep persists.