Sleep Cycle Calculator
Wake up at the right point in your cycle.
Sleep Cycle Calculator
Find optimal bedtimes or wake times based on 90-minute sleep cycles.
Best Bedtime
6 cycles — 9h
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What This Calculator Does
The Sleep Cycle Calculator determines the best bedtime or wake-up time based on 90-minute sleep cycles. Waking up at the end of a cycle means feeling more refreshed.
How It Works
A full sleep cycle is approximately 90 minutes. It takes about 15 minutes to fall asleep. The calculator counts backward from your wake time in 90-minute increments, minus 15 minutes for sleep onset.
Example
If you need to wake at 7:00 AM, ideal bedtimes are: 11:15 PM (5 cycles, 7h 45m), 9:45 PM (6 cycles, 9h 15m), or 12:45 AM (4 cycles, 6h 15m).
Formula
Bedtime = Wake Time - (Cycles x 90 min) - 15 min fall asleepReading the Results
Bedtimes
Recommended times to fall asleep, each aligned with the end of a complete sleep cycle.
Sleep Duration
Total time in bed for each option, including fall-asleep buffer.
Frequently Asked Questions
Why 90 minutes?
A complete sleep cycle (light, deep, REM) takes about 90 minutes on average. Waking between cycles reduces sleep inertia (grogginess).
Does it account for individual variation?
The 90-minute average varies between people (80-100 minutes). Use the calculator as a starting point and adjust based on how you feel.
What about naps?
For naps, 20-30 minutes (one cycle minus deep sleep) or a full 90 minutes works best. Avoid 45-60 minute naps that wake you mid-cycle.