Health & Fitness
Sleep Cycles Calculator
Turn a sleep duration into 90-minute sleep cycles and nearby cycle-friendly durations.
The result shows how many 90-minute cycles fit into the sleep duration entered, together with nearby whole-cycle totals that can help in choosing a waking point.
Formula
Sleep cycles equal total sleep hours divided by 1.5, since one cycle averages about 90 minutes.
How it works
Total sleep is divided by the average cycle length. Whole numbers of cycles are often suggested as waking points, because waking mid-cycle can feel groggier than waking between cycles.
Worked example
For example, 7.5 hours ÷ 1.5 = 5.0 cycles of 90 minutes.
FAQs
Is every cycle exactly 90 minutes?
No. Cycles vary from 70 to 120 minutes across the night.
Is 5 cycles enough?
For many adults 5 cycles (7.5 hours) is a reasonable target.
Does this diagnose sleep problems?
No. Persistent sleep trouble deserves proper advice.
General information only, not medical advice.
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