🌙 Sleep Cycle

I want to...

🧠 How this works

The 90-Minute Rule: Humans sleep in cycles of ~90 minutes. If you wake up between cycles, you feel refreshed.

The Buffer: This calculator adds the time it takes you to fall asleep (avg 14 mins) so the math is perfect.

Optimal: 5-6 Cycles (7.5 - 9 Hours)
Risk: < 4 Cycles (Groggy Risk)

How to use Sleep Cycle Calculator

Wake up feeling refreshed with the Sleep Cycle Calculator. By tracking standard 90-minute REM cycles, this tool helps you calculate the exact best bedtimes if you need to wake up at a certain hour, or the best wake times if you are going to sleep right now.

It also provides highly useful information on sleep health to improve your daily energy. This health utility is entirely free, incredibly fast, and works seamlessly offline without needing an app.