Sleep Duration Calculator

Calculate the best time to go to bed or wake up based on 90-minute sleep cycles. Optimize your sleep!

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Choose whether you want to know what time to wake up or go to bed, then enter the corresponding time.

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Optimize your sleep cycles

Calculation mode

I want to wake up at... I will go to bed at...

Time (HH:MM)

Optimal sleep times

Recommended bedtimes

Recommended bedtimes
00:46 (4 cycles - 6h)
23:16 (5 cycles - 7h30)
21:46 (6 cycles - 9h)
20:16 (7 cycles - 10h30)

Understanding Sleep Cycles

Sleep is organized in cycles of approximately 90 minutes each. Each cycle includes several phases: light sleep, deep sleep, and REM (Rapid Eye Movement) sleep.

Why respect sleep cycles?

Waking up in the middle of a cycle causes feelings of tiredness and drowsiness, even after a long night. Waking up at the end of a complete cycle generally leaves you feeling more rested and alert.

How many cycles per night?

4 cycles = 6 hours of sleep: recommended minimum

5 cycles = 7.5 hours of sleep: good night's sleep

6 cycles = 9 hours of sleep: long and restful night

Time to fall asleep

Our calculator accounts for an average fall-asleep time of 14 minutes. This delay corresponds to the average time a healthy person takes to fall asleep after lying down.

Tip: Sleep schedule consistency is as important as duration. Try to go to bed and wake up at the same times every day, even on weekends.