Find the best time to sleep or wake up based on 90-minute sleep cycles.
A sleep cycle lasts approximately 90 minutes, moving through light sleep, deep sleep, and REM sleep. Waking up at the end of a complete cycle leaves you feeling refreshed. Waking mid-cycle causes grogginess.
Enter either your target wake-up time or your planned bedtime, then click Calculate. The tool shows the ideal times based on 3 to 6 complete sleep cycles.