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Sleep Cycle & REM Optimizer

Wake up refreshed without morning grogginess. Calculate optimal sleep and wake times based on 90-minute human sleep cycles.

Sleep Schedule

Suggested Bedtimes (90-min Cycles)

* Calculations factor in an average of 14 minutes to fall asleep. Waking up between REM cycles prevents sleep inertia and grogginess.

The Science of 90-Minute Sleep Cycles

Sleep isn't a uniform state of rest. Throughout the night, human brains cycle through distinct stages of light sleep, deep slow-wave sleep, and REM (dreaming) sleep. Each complete cycle lasts roughly 90 minutes. Waking up in the middle of deep sleep triggers "sleep inertia"—that heavy, groggy feeling that can ruin your morning. By timing your sleep in 90-minute increments, you wake up at the end of a cycle during light sleep feeling refreshed.

Frequently Asked Questions

How long is a human sleep cycle?

A complete human sleep cycle lasts approximately 90 minutes.

Methodology & Data Citations

Calculations execute 100% client-side based on circadian chronobiology and 90-minute sleep cycle research.