Health & Fitness
Bedtime From Wake Time Calculator
Work backwards from a wake time in whole 90-minute sleep cycles to find a bedtime.
This result is the time to aim to fall asleep, so that the chosen number of full sleep cycles fits before the wake-up time.
Formula
Bedtime equals wake time minus cycles times 90 minutes, minus 15 minutes allowed to fall asleep.
How it works
Whole cycles are counted backwards from the wake time, with a small allowance for falling asleep. The result is a lights-out target, not a guarantee of waking refreshed.
Worked example
For example, with a wake-up time of 07:00 and 5 sleep cycles, the bedtime is 07:00 minus 5 × 90 minutes minus 15 minutes, which gives 23:15 on the previous evening.
FAQs
Should I count 15 minutes to fall asleep?
It is a common allowance; use more if you usually take longer.
What if the bedtime looks too early?
Try one fewer cycle, or an earlier wake time.
Does this fix insomnia?
No. It is a scheduling aid, not a treatment.
General information only, not medical advice.
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