Understanding sleep cycles
Sleep does not happen in identical 90-minute blocks. The calculator uses cycle timing as a practical planning estimate rather than a prediction of your exact sleep stages.
Why use cycle timing?
During the night, sleep moves through repeating stages. Planning around approximate cycles can provide convenient bedtime and wake-up options, but total sleep duration and individual sleep needs remain important.
Why include time to fall asleep?
Going to bed is not the same as falling asleep. The calculator therefore lets you add an estimated sleep-onset period before calculating the sleep cycles.
Use the results as a planning aid
If you regularly struggle to sleep, feel excessively sleepy, or have concerns about your health, a calculator is not a substitute for professional medical advice.
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