- 6 cycles · 9 hours asleep
- 21:45
- 5 cycles · 7.5 hours asleep
- 23:15
- 4 cycles · 6 hours asleep
- 00:45
How it works
Time in bed exceeds planned sleep
For a 07:00 wake time, eight hours asleep plus 30 minutes to fall asleep calls for getting into bed at 22:30 in this model. A 23:00 bedtime provides only 7.5 planned sleep hours before unmodeled nighttime awakenings.
Planning a sleep window with explicit assumptions
The sleep planner works from a chosen bedtime or wake time and the duration assumptions shown in the selected mode. A cycle-based schedule is a planning model, not a measurement of a person's sleep stages. Include the entered time to fall asleep consistently when comparing options. The result does not diagnose a sleep problem or guarantee how rested someone will feel.
Sleep-cycle planner: formula and assumptions
Illustrative times use 90-minute cycles plus sleep-onset time.
Real sleep cycles vary in duration. This planner does not measure your sleep stages or replace age-appropriate sleep-duration guidance.
Plan a sleep duration: formula and assumptions
Bedtime=wake time−sleep duration−sleep-onset time; reverse for wake time.
Sleep duration is entered directly. This planning tool does not predict sleep stages.
Worked example
Using the Sleep-cycle planner example:
- Target time
- 07:00
- Target is
- Wake-up time
- Time to fall asleep (minutes)
- 15
Illustrative times use 90-minute cycles plus sleep-onset time.
Example result
6 cycles · 9 hours asleep: 21:45
5 cycles · 7.5 hours asleep: 23:15
4 cycles · 6 hours asleep: 00:45
These are illustrative inputs. Change the values to explore a different scenario.
What to keep in mind
Adults generally need sufficient total sleep; a cycle-based time is not a guarantee of waking refreshed.
Formula references
References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.
Common questions
Are real sleep cycles always 90 minutes long?
No. The cycle planner uses that illustrative interval, but actual cycle lengths vary and the tool does not measure sleep stages.
Does a suggested cycle time guarantee I will wake refreshed?
No. Total sleep, individual needs and sleep quality matter. A clock-time estimate cannot guarantee how someone will feel on waking.
Prepared by Finflo. See our methodology and editorial policy.