Sleep Cycle Calculator
Sleep happens in 90-minute cycles. Waking at the end of a cycle leaves you alert; waking mid-cycle leaves you groggy. Pick a time and we'll suggest cycle-aligned alternatives.
Bedtimes for 07:00
Long sleep — best for recovery
Recommended for most adults
Minimum — only if 5 isn't possible
Calculation assumes ~14 minutes to fall asleep. If you typically take longer, add that to your bedtime.
Why 90 minutes
A full sleep cycle averages 90 minutes — moving through light, deep, and REM stages. Waking at the end of a cycle (when you're closest to light sleep) feels easier than being jolted out of deep sleep mid-cycle.
This is why a "short" 5-cycle (7.5h) sleep can feel better than a "long" 5h20m sleep that cuts off mid-cycle. Cycles vary 80–110 minutes between people, so treat this as a starting point.