ZZZcalc.com

About

ZZZCalc determines the best time for you to fall asleep or to wake up by factoring in 90 minute sleep cycles and the typical 14 minutes needed to fall asleep. Conventional sleep guidance often overlooks these cycles, but interrupting one can lead to grogginess regardless of total sleep time. The tool includes a bedtime calculator, a wake up calculator, a mode for shift workers, and a nap calculator. It is entirely free to use and does not require an account.