The Science of 90-Minute Sleep Cycles
Why 90 minutes is the magic number for a complete sleep cycle, and how to use this to wake up refreshed.
Read MoreWhen Should You Wake Up?
Science-based sleep cycle calculator. Instant results. No sign-up.
Current time
If you go to bed right now, you'll spend ~15 minutes falling asleep. Here are your optimal wake-up times:
Results update automatically. Includes 15 minutes to fall asleep.
Sleep Better Tonight
These simple tools can make a real difference in your sleep quality.
Quality Sleep Mask
Block out 100% of light for deeper sleep. A dark room signals your brain to produce melatonin naturally.
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Drown out disruptive sounds with consistent background noise. Helps you fall asleep faster and stay asleep longer.
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Temperature-regulated pillow that stays cool all night. The optimal sleep temperature is 60-67 degrees Fahrenheit.
View on AmazonHow It Works
1
90-Minute Cycles
Each sleep cycle lasts about 90 minutes. You cycle through light sleep, deep sleep, and REM sleep.
2
Wake at Cycle End
Waking up mid-cycle causes grogginess. Waking at the end of a cycle feels natural and refreshing.
3
We Do the Math
We add 15 minutes to fall asleep, then calculate 6 optimal wake-up times across 1-6 sleep cycles.