Sleep Cycle Calculator
Calculate natural 90-minute sleep cycles to wake up feeling refreshed and avoid sleep inertia grogginess.
Sleep Cycle Calculator
Calculate natural 90-minute sleep cycles to wake up feeling refreshed and avoid sleep inertia grogginess.
Optimal Times to Fall Asleep
How to Use Sleep Cycle Calculator
1. Choose Bedtime or Wake Time
Select when you plan to go to sleep, or pick your desired wake-up time. You can also click "Sleep Now" for instant recommendations.
2. Calculate 90-Minute REM Cycles
The calculator factors in the average 14 minutes it takes to fall asleep, then calculates complete 90-minute REM sleep cycles.
3. Wake Up Feeling Refreshed
Set your alarm for one of the suggested times (ideally 5 or 6 full cycles) to avoid waking up groggy in the middle of deep sleep.
How This Utility Works
Chronobiology sleep cycle planner. Computes optimal bedtimes and wake times aligned with natural 90-minute non-REM and REM sleep cycles, helping prevent sleep inertia grogginess and morning fatigue.
Your body metrics, age, weight, and fitness statistics remain exclusively on your device. No health data is stored in remote databases.
Frequently Asked Questions
How long is a typical human sleep cycle?
A healthy adult sleep cycle lasts approximately 90 minutes. Waking up at the end of a cycle rather than in the middle of deep slow-wave sleep leaves you feeling clear-headed.