Sleep Cycle Calculator
A sleep cycle calculator works backward (or forward) from your alarm in 90-minute blocks so you wake up at the end of a cycle instead of in the middle of deep sleep. Enter a time below to see cycle-aligned options.
Calculate your sleep cycles
Switch between “wake up at” and “go to bed at” to plan from either end of the night.
Find Your Perfect Sleep Schedule
Calculate optimal bedtimes and wake-up times based on natural sleep cycles for better rest and energy.
Enter a time above to see recommendations
What a sleep cycle is
Each cycle moves through light sleep (N1, N2), deep sleep (N3), and REM sleep. Early in the night your cycles hold more deep sleep; later cycles hold more REM. Waking during deep sleep is what causes the heavy, groggy feeling called sleep inertia.
How to use the results
- Pick the option that gives you 5-6 cycles when possible (about 7.5-9 hours).
- The calculator already adds ~15 minutes to fall asleep, so the time shown is when to get into bed.
- If you wake naturally a few minutes before the alarm, get up, because you are at a cycle boundary.
Want the science first? Read how the 90-minute sleep cycle works, or check how much sleep you need by age.