Understanding your calculation
Method, example and limitations
How the calculation works
A sleep-time estimate works backward or forward from a chosen bedtime or wake time using assumed cycle durations and sleep-onset time.
Example to check
If the plan allows eight hours asleep plus 15 minutes to fall asleep before a 07:00 wake time, the corresponding bedtime is 22:45 the previous day.
Before using the result
Sleep cycles vary and a fixed cycle length is only a planning assumption. Persistent sleep problems or daytime impairment deserve medical assessment.