Clock & Timer Blog

How to Track Sleep Cycles with a Free Online Sleep Calculator

Getting a good night's sleep isn’t just about the number of hours — it’s about completing full sleep cycles. Using a sleep calculator can help you time your sleep and wake up feeling refreshed, not groggy.

What Are Sleep Cycles?

Each night, your body goes through stages of light sleep, deep sleep, and REM sleep. A full cycle typically lasts about 90 minutes. Waking up in the middle of deep sleep can leave you feeling exhausted, even if you slept for a long time.

How a Sleep Calculator Helps

Try It Yourself

Plan your next bedtime smarter. Our Sleep Calculator is launching soon — stay tuned!

In the meantime, check out our world clock to find the best times no matter where you are!