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Sleep Calculator
Calculate your ideal bedtime or wake-up time based on 90-minute sleep cycles.
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About this tool
Our bodies sleep in 90-minute cycles — waking between cycles leaves you feeling refreshed. Enter your target wake-up time to see the best bedtimes, or enter when you plan to sleep to see optimal alarm times. A 15-minute fall-asleep buffer is included, and each result shows how many cycles you will get.
How to use
- 1 Step 1: Choose a mode: 'Wake up at…', 'Sleep at…', or 'Wake up in X hours'.
- 2 Step 2: Enter your target time or hours. The current time is pre-filled for convenience.
- 3 Step 3: Review the five recommended times, each labeled with the number of sleep cycles.
- 4 Step 4: Read the sleep stage tips to understand REM, light, and deep sleep.