Sleep Calculator
Find your optimal sleep and wake times
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Go to bed at one of these times:
How Sleep Cycles Work
Sleep happens in approximately 90-minute cycles. Waking up at the end of a cycle (rather than in the middle) helps you feel refreshed instead of groggy.
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Each block = 90 minutes (1 sleep cycle)
The calculator also adds 15 minutes for the average time it takes to fall asleep. For most adults, 5-6 cycles (7.5-9 hours) is ideal.