Calculate ideal bedtimes based on 90-minute sleep cycles so you wake up at the end of a cycle instead of in the middle of deep sleep.
How it works
- Enter the time you need to wake up.
- The calculator lists bedtimes for 4, 5, and 6 full sleep cycles.
- Choose the bedtime that gives you enough sleep without waking mid-cycle.
Frequently asked questions
Why 90-minute cycles?
Sleep progresses through light, deep, and REM stages in roughly 90-minute cycles. Waking at the end of a cycle feels more refreshed.
How much sleep do I need?
Most adults need 7–9 hours. The tool shows options in that range.
Does this replace a sleep study?
No. It is a practical guide based on average cycle length. Individual sleep varies.