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Find the best bedtime or wake-up time using 90-minute sleep cycles.
Calculate the ideal bedtime or wake-up time based on natural 90-minute sleep cycles. Pick the time you need to wake up and get recommended bedtimes, or check the best wake-up times if you go to bed right now. Adjust cycle length and how long it takes you to fall asleep for personalized results — waking at the end of a cycle leaves you refreshed instead of groggy.
The Sleep Cycle Calculator helps optimize your rest by calculating ideal bedtimes or wake-up times based on natural 90-minute sleep cycles. It allows you to customize cycle length and fall-asleep time for tailored results, ensuring you wake up between cycles rather than during deep sleep to minimize morning grogginess. Completely free and browser-based, it delivers quick, straightforward scheduling without requiring account registration or software installation.
Good to know: This tool provides general estimates based on average sleep cycles and does not replace professional medical advice for sleep disorders.
Calculate the perfect time to wake up or go to bed by aligning with natural 90-minute sleep cycles.
Select your calculation method
Choose whether you want to calculate the best bedtime based on a wake-up time or find wake-up times based on when you go to bed.
Input your desired time
Enter the specific time you need to wake up or the time you plan to fall asleep into the calculator field.
Adjust sleep cycle settings
Customize the default 90-minute cycle length and the time it takes you to fall asleep for more personalized results.
Review the recommended sleep windows
Analyze the generated list of optimal times that align with the end of your natural REM sleep cycles.
Set your alarm accordingly
Pick the suggested time that provides enough total rest and set your alarm to wake up feeling refreshed instead of groggy.
Estimated time: PT1M
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To wake up at 7:00 AM feeling rested, fall asleep at one of these times (includes 15 min to fall asleep).
9:45 PM
9 hrs · 6 cycles
11:15 PM
7.5 hrs · 5 cycles
12:45 AM
6 hrs · 4 cycles
2:15 AM
4.5 hrs · 3 cycles
Sleep happens in cycles of roughly 90 minutes, moving through light sleep, deep sleep, and REM. Waking up at the end of a cycle — rather than in the middle of deep sleep — leaves you feeling far more refreshed. Most adults need 5–6 full cycles (about 7.5–9 hours) per night.
