Sleep Calculator
I need to wake up at...
Find the best bedtime to wake up refreshed
I'm going to bed at...
Find the best wake-up times based on your bedtime
Formula
Wake Time = Bedtime + 15 min (fall asleep) + N x 90 min cycles
Frequently Asked Questions
What is a sleep cycle?
A sleep cycle lasts about 90 minutes and consists of light sleep, deep sleep, and REM sleep. Adults typically need 5-6 cycles (7.5-9 hours) per night.
Why do I feel tired even after 8 hours of sleep?
You may be waking up in the middle of a sleep cycle. Try adjusting your alarm to coincide with the end of a 90-minute cycle. For example, 7.5 hours (5 cycles) may feel more restful than 8 hours.
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