😴 Life Math
Sleep Cycle Calculator
Calculates ideal bedtimes or wake-up times based on 90-minute sleep cycles, so you wake up between cycles instead of mid-cycle.
How to use it
- Choose "I want to wake up at…" and enter your target wake time, or choose "I'm going to sleep now" for instant results.
- Press Calculate.
- Review the suggested times, each representing a different number of full sleep cycles.
- Pick the option that gives you the most complete cycles for your schedule.
FAQ
Why 90-minute cycles?
A full sleep cycle averages about 90 minutes; waking up at the end of a cycle rather than mid-cycle tends to feel less groggy.
Why does it add 15 minutes?
That accounts for the average time it takes most people to actually fall asleep after getting into bed.
How many cycles should I aim for?
5–6 cycles (7.5–9 hours) is a common target for adults, but individual sleep needs vary.
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