Sleep Cycle & Smart Wake-Up Alarm Calculator

Formula & Calculation Methodology

Wake Time = Bedtime + 15 min latency + (Cycle Count × 90 minutes). 5 to 6 cycles (7.5 to 9 hours) recommended for adults.

Step-by-Step Worked Example

Going to bed now (e.g. 11:00 PM)

1. 15 min buffer to fall asleep -> Sleep begins at 11:15 PM
2. 4 Cycles (6.0 Hours) -> Wake at 5:15 AM
3. 5 Cycles (7.5 Hours) -> Wake at 6:45 AM (Optimal)
4. 6 Cycles (9.0 Hours) -> Wake at 8:15 AM (Recommended)

The Science of 90-Minute REM Sleep Cycles

Human sleep consists of alternating cycles between light sleep, deep slow-wave sleep, and Rapid Eye Movement (REM) sleep, each lasting approximately 90 minutes.

Waking up in the middle of deep sleep causes "sleep inertia" (morning grogginess), while waking at the end of a cycle feels effortless and energizing.

Frequently Asked Questions