Sleep Calculator
Calculate optimal bedtimes or wake times based on sleep cycles.
Suggested Bedtimes
9 Hours (6 Sleep Cycles)
22:00
7.5 Hours (5 Sleep Cycles)
23:30
6 Hours (4 Sleep Cycles)
01:00
4.5 Hours (3 Sleep Cycles)
02:30
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Sleep Calculator: Bedtime or Wake Time by 90-Minute Cycles
Suggest four bedtimes or wake times based on 90-minute sleep cycles (about 4.5, 6, 7.5, or 9 hours from your chosen clock time). Waking between cycles may feel lighter than waking mid deep sleep. Timing aid only, not a sleep disorder assessment.
How to use
Use the Wake Time tab to work backward from when you must get up, or the Bedtime tab to see forward wake options. Enter your target time. The grid lists four options with hours and cycle count; the first two rows are highlighted as common 5- or 6-cycle targets. Pick a time that fits your schedule, not only the shortest sleep block.
Example
Alarm at 07:00 in wake mode may suggest bed around 22:00 (six cycles, 9 h), 23:30 (five cycles, 7.5 h), 01:00 (four cycles), or 02:30 (three cycles). If you need 15 minutes to fall asleep, aim to be in bed before the time shown.
Tips
Most people need a few minutes to fall asleep after lying down. Regular wake times help more than one perfect night. This tool does not measure sleep quality or replace care for insomnia, sleep apnea, or ongoing fatigue.