Sleep Calculator
Calculate optimal wake-up time based on 90-minute sleep cycles to wake up feeling refreshed.
If you fall asleep now, wake up at:
(Assuming 15 minutes to fall asleep)
Go to sleep at these times to wake up refreshed:
Sleep Tips
- • Average sleep cycle is about 90 minutes
- • Waking between cycles feels more refreshing
- • Adults need 7-9 hours of sleep (4-6 cycles)
- • Maintain a consistent sleep schedule
What is a Sleep Calculator?
A sleep calculator helps you find the ideal bedtime or wake-up time based on natural sleep cycles. Human sleep follows roughly 90-minute cycles consisting of light sleep, deep sleep, and REM stages. Waking at the end of a complete cycle leaves you feeling refreshed rather than groggy. This tool factors in the average sleep onset time of about 15 minutes, so the recommendations reflect when you actually fall asleep rather than when you get into bed.
How It Works
The sleep calculator computes optimal bedtime/wake times based on sleep cycles (~90 minutes each). A typical cycle repeats non-REM (N1→N2→N3) and REM stages, totaling ~90 minutes. Accounting for sleep onset time (~14 minutes), waking after completing 4-6 cycles (6-9 hours) feels most refreshed.
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