When should you go to bed and wake up to get enough sleep?
Sleep runs in ~90-minute cycles: waking is easiest at a cycle boundary. Set your wake-up time and we’ll compute when to go to bed.
Best bedtime: 5 cycles (7.5 h of sleep) + ~15 min to fall asleep. Alternatives: 21:45 — 9 h (6 cycles), 00:45 — 6 h (4 cycles, a one-off minimum, not a routine).
Anchors: AASM/SRS (7+ hours for adults); the ~90-minute cycle is an average and varies between people. A hint, not a prescription.
How to use the result
How it works
The calculator counts back full 90-minute cycles and adds about 15 minutes to fall asleep. The main adult anchor is at least 7 hours of sleep regularly.
How to read the result
Choose an option that provides enough sleep and fits your schedule. A consistent wake time is usually more useful than targeting a perfect minute.
Limitations
Cycles vary between people and nights, so this is a starting point rather than an exact body schedule. Persistent insomnia, severe daytime sleepiness or breathing pauses warrant medical advice.
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Take the short health-factor map and see how this connects to your own lifestyle.