Sleep Cycle Calculator
Time your sleep around 90-minute cycles so you wake up refreshed, not groggy.
Recommended Times
Based on 90-minute sleep cycles plus ~15 minutes to fall asleep.
Why Sleep Cycles Matter More Than Total Hours
Sleep happens in cycles of roughly 90 minutes, moving through light sleep, deep sleep, and REM stages. Waking up in the middle of a deep sleep stage tends to leave you feeling groggy, even if you slept a reasonable number of hours. Waking up at the end of a full cycle, on the other hand, tends to feel noticeably more refreshing.
How This Calculator Works
Choose whether you want to wake up at a specific time or are heading to bed right now. The tool then works backward or forward in 90-minute increments, adding roughly 15 minutes for the time it typically takes to fall asleep, and shows you several optimal bed or wake times — generally aiming for 5 to 6 full cycles (around 7.5 to 9 hours).
Tips for Better Sleep Quality
Keep a consistent sleep and wake schedule, even on weekends. Avoid screens and caffeine in the hour before bed. A cool, dark, quiet room supports deeper sleep cycles, and consistent timing helps your body anticipate and settle into each stage more efficiently.