Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles to wake up feeling refreshed.
I want to calculate my…
Best bedtimes (wake up feeling refreshed):
Based on 90-minute sleep cycles and ~15 minutes to fall asleep. Adults need 5–6 complete cycles (7.5–9 hours) for optimal rest.
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What is a Sleep Calculator?
A sleep calculator helps you determine the best time to go to bed or wake up based on 90-minute sleep cycles. Sleep occurs in cycles that alternate between light sleep (NREM stages 1–3) and REM (Rapid Eye Movement) sleep. Waking up at the end of a complete cycle, during the lightest stage of sleep, minimizes grogginess and sleep inertia.
Most adults need 5–6 complete sleep cycles per night, which equals 7.5–9 hours of sleep. The calculator adds 15 minutes of fall-asleep time to ensure the cycles are properly aligned with your actual sleep onset.
Sleep quality matters as much as quantity. Consistent sleep and wake times — even on weekends — help regulate your circadian rhythm, making it easier to fall asleep and wake up naturally. Exposure to blue light from screens in the hour before bed suppresses melatonin production and delays sleep onset.
How to Use the Sleep Calculator
Find the perfect bedtime or wake-up time to feel refreshed.
- 1
Choose your calculation direction
Select "I want to wake up at..." to find the best bedtime, or "I want to go to bed at..." to find the best wake-up times.
- 2
Enter your target time
Input your desired wake-up time or bedtime.
- 3
View your optimal times
The calculator shows multiple bedtime or wake-up options, each aligned with the end of a complete 90-minute sleep cycle.
- 4
Choose the right number of cycles
For most adults, 5 cycles (7.5 hours) or 6 cycles (9 hours) is ideal. Select the option that best fits your schedule.
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