Sleep Cycle Calculator
Find the best times to wake up or go to sleep to feel rested — based on 90-minute sleep cycles.
About Sleep Cycles
What is a sleep cycle?
A sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM (dream) sleep. Waking up between cycles — rather than during deep sleep — helps you feel more refreshed.
How many sleep cycles do I need?
Most adults feel best with 5–6 complete cycles, which equals 7.5–9 hours of sleep. Some people function well on 4 cycles (6 hours) but this varies by individual.