Sleep Cycle Calculator
Sleep in sync with your brain's natural stages. Wake up at the completion of a 90-minute cycle to banish morning grogginess.
*Calculations include a standard 15-minute buffer representing the average latency to fall asleep.
90-Minute Sleep Cycles
Human sleep is composed of repeating cycles averaging 90 minutes. Each cycle proceeds from Light Sleep to Deep Sleep, and concludes with REM (Dreaming) sleep.
The Danger of Sleep Inertia
If your alarm goes off during a Deep Sleep stage, your brain is forced from slow-wave states instantly, causing confusion, fatigue, and heavy limbs for hours.
Re-anchoring Your Cycle
To lock in your sleep cycle length, get bright sunlight in your eyes within 30 minutes of waking up. This programs your biological timer for next night's cycle.
Get Daily Circadian Protocols
Stop guessing your biology. ARC automatically calculates your cycle lengths, schedules sunlight reminders, and adapts to poor sleep in real time.