Why 90-minute cycles?

A full sleep cycle (light, deep, and REM sleep) averages about 90 minutes. Waking up between cycles rather than mid-cycle tends to feel more refreshing.

Sleep Calculator

Find the best time to sleep or wake up

Wake-up Time

Your Result

Recommended Bedtimes

09:45 PM

9h (6 cycles)

11:15 PM

7.5h (5 cycles)

12:45 AM

6h (4 cycles)

02:15 AM

4.5h (3 cycles)

Each option allows for complete 90-minute sleep cycles

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Formula Used

Bedtime = Wake Time − (Sleep Cycles × 90 minutes) − 15 minutes to fall asleep

Step-by-Step Explanation

1Enter your desired wake-up time.
2See several bedtime options, each completing full 90-minute sleep cycles.

Worked Examples

Example 1

Wake up at 7:00 AM

WakeTime=07:00

Bedtime options include 9:30 PM (6 cycles) and 11:00 PM (5 cycles)

Frequently Asked Questions

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