Bedtime Candidates from Wake Time
Build a timetable by subtracting fixed sleep blocks and a falling-asleep allowance. NHLBI describes cycles varying roughly from 80 to 100 minutes, so 90 minutes is not a personal constant.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
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How to use this tool
Enter wake time and assumed minutes to fall asleep. The calculator lays out three to six 90-minute blocks; check whether a bedtime lies on the previous day when it crosses midnight.
Results and examples
These candidates are time subtraction, not an alarm based on measured sleep stages. A short three-block option is not a recommendation for sufficient habitual sleep; allow adequate total sleep separately.
Worked example
A 07:00 wake time, 15-minute onset allowance and five blocks gives a 23:15 bedtime candidate.
Limitations
- Actual REM and deep-sleep boundaries are not predicted.
- Individual sleep need, sleep disorders and night awakenings are excluded.
Fields
| Field | Guidance and constraints |
|---|---|
| Wake time | Check the unit and format displayed beside this field. |
| Time to fall asleep (min) | Check the unit and format displayed beside this field. |
| 90-minute-cycle bedtimes | Check the unit and format displayed beside this field. |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
Will that bedtime guarantee feeling refreshed?
No. Real sleep cycles and quality vary.
Are three blocks enough?
The 4.5-hour arithmetic option is not an adequate-sleep recommendation.
Related tools
You do not need to start over. Continue with the tool that fits your next step.
