Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Health, Fitness & Wellness
Sleep Cycle Calculator — What Time Should I Wake Up?
Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
Pick bedtime or wake time aligned to 90-minute sleep cycles. Estimates only—not a diagnosis or prescription.
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Inputs
01439
36
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Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
- Interpret
Treat this as a planning estimate
Primary result: Suggested bedtime = 11:15 PM. Re-run with optimistic and pessimistic inputs to understand the range—not just a single point.
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Wake time (min from midnight)
The “Wake time (min from midnight)” value used in this tool’s formula. Adjust it to see results update live.
Sleep cycles (90 min each)
The “Sleep cycles (90 min each)” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Pick bedtime or wake time aligned to 90-minute sleep cycles. Estimates only—not a diagnosis or prescription. Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep. Example: Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
Example: Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
When to use this Sleep Cycle
Common use cases
- Pick bedtime or wake time aligned to 90-minute sleep cycles.
- Sanity-check with this case: Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
- The relationship is: Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
Localized examples
- Health, Fitness & Wellness: the example on this page uses the same formula as the widget.
What you get
- Fields: Wake time (min from midnight), Sleep cycles (90 min each)
- Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
- Example on the page: Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
How to Calculate Sleep Cycle Step-by-Step
- 1Enter Wake time (min from midnight), Sleep cycles (90 min each). Use the values you have, not a catalog average, unless that is all you know.
- 2Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
- 3Worked case: Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
- 4If this number would change a drug, a diet, or a return-to-play call, take it to a clinician. The page never examined you.
Governing formula
Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
Wake 7:00 AM, 5 cycles → bedtime ~10:45 PM.
Example: set Wake time (min from midnight) = 420, Sleep cycles (90 min each) = 5, then read the result.
Variable definitions
- wakeTimeMin
Wake time (min from midnight)
The “Wake time (min from midnight)” field. Default 420; typical range 0–1439.
- sleepCycles
Sleep cycles (90 min each)
The “Sleep cycles (90 min each)” field. Default 5; typical range 3–6.
- The formula (Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.) does not see labs, medications, sleep, or injury history. A clinician does.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Bedtime = wake time − (cycles × 90 min) − 15 min to fall asleep.
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Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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