Sleep Cycle Calculator
Wake up refreshed, not tired
Optimize your rest with our Sleep Cycle Calculator. Waking up in the middle of a deep sleep cycle—rather than at the end of one—is what causes “sleep inertia” or feeling groggy. Since the average sleep cycle lasts about 90 minutes, this tool works backward from your desired wake time to find the best times to fall asleep. Aiming for 5 or 6 full cycles ensures you wake up at a lighter stage of sleep, feeling alert and ready for the day.