Sleep Cycle Calculator
Suggest bedtimes or wake times in 90-minute cycles with a 15-minute fall-asleep buffer. Not medical advice.
This tool is not medical advice. Sleep needs vary. These times are heuristics based on ~90-minute cycles and a 15-minute fall-asleep buffer.
Suggested bedtimes
Example
Wake at 07:00 → try sleeping at about 23:15 (5 cycles) or 21:45 (6 cycles), including a 15-minute buffer.
FAQ
From your chosen time, we add or subtract 15 minutes plus N × 90 minutes for 3–6 cycles (about 4.5–9 hours of sleep).
No. Cycle length and sleep onset vary. Use suggestions as a planning aid only.