Sleep Calculator
Wake up refreshed by timing your sleep around complete 90-minute sleep cycles. Tell us when you need to wake up, and we'll suggest the best bedtimes — or vice versa.
Sleep Calculator
health calculator
How It Works
Formula
Sleep cycles are ~90 minutes. We add 15 minutes to fall asleep, then count back/forward in 90-minute cycles.
Examples
Wake at 07:00
Best bedtime around 21:45 for 6 full cycles.
Frequently Asked Questions
How do sleep cycles work?
Sleep occurs in cycles of about 90 minutes, moving through light, deep, and REM stages. Waking at the end of a cycle (rather than mid-cycle) helps you feel more refreshed.
How many hours of sleep do I need?
Most adults need 7-9 hours, which is about 5-6 complete sleep cycles. The calculator targets these cycle counts to align your wake time with the end of a cycle.
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