CLC-13Calculators
Sleep Calculator
Best bedtimes by 90-minute cycles
CLC-13Result
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Sleep Calculator
Suggests bedtimes (or wake-up times) aligned with 90-minute sleep cycles plus 15 minutes to fall asleep. Waking between cycles feels easier than mid-cycle.
Frequently asked questions
Why 90 minutes?
A full sleep cycle — light, deep and REM sleep — averages about 90 minutes. Waking at a cycle boundary feels lighter.
How many cycles do I need?
Most adults feel best after 5–6 cycles, i.e. 7.5–9 hours of sleep.