Choose a wake-up time and see suggested sleep times based on 90-minute sleep cycles.
Use this sleep cycle calculator to work backward from your wake-up time and estimate sleep times based on 90-minute cycles.
These results are meant to be practical planning guides. Real sleep can vary, but many people find it helpful to time sleep in full cycles instead of only counting total hours.
A typical sleep cycle is often described as lasting about 90 minutes, though it can vary from person to person. This tool uses that common estimate as a simple planning guide.
Many people do not fall asleep the exact second they get into bed. The extra 15 minutes gives a more realistic bedtime estimate.