Sleep Cycle Calculator

A sleep cycle calculator helps you find the best times to fall asleep or wake up based on your natural sleep cycles. Sleep occurs in cycles of approximately 90 minutes, and waking up at the end of a complete cycle — rather than in the middle — helps you feel more refreshed and alert.

This calculator accounts for the average time it takes to fall asleep (14 minutes) and calculates optimal times based on completing 3 to 6 full sleep cycles. Adults typically need 5-6 cycles (7.5-9 hours) per night for optimal health and cognitive function.

You can use two modes: enter your desired wake-up time to find the best bedtimes, or enter your planned bedtime to find the best wake-up times. Either way, aligning your sleep with natural cycles can dramatically improve how you feel in the morning.

1. Choose your mode — "I want to wake up at" or "I want to sleep at."
2. Enter your time — Use 24-hour format (0-23 hours, 0-59 minutes).
3. Review recommendations — See optimal times for 3, 4, 5, and 6 complete sleep cycles.
4. Choose 5-6 cycles — For the recommended 7.5-9 hours of sleep per night.

Sleep Cycle Duration: 90 minutes per cycle

Fall Asleep Time: Average 14 minutes

Wake-up mode: Bedtime = Wake time - (cycles × 90 min) - 14 min

Sleep mode: Wake time = Bedtime + 14 min + (cycles × 90 min)

Example: Wake at 7:00 AM, 6 cycles → Bedtime = 7:00 - 9h 14m = 9:46 PM