Polar Sleep Plus Stages Alternative

Polar Sleep Plus Stages tracks sleep architecture using accelerometer movement analysis and PPG heart rate sensing to classify light, deep, and REM sleep stages, plus interruptions and wake periods. It produces a sleep score from three components: sleep amount (total time), solidity (interruptions and awakenings), and regeneration (percentage of deep + REM sleep). Additionally, it measures sleep latency (how fast you fall asleep) and sleep rhythm consistency — tracking how regular your sleep-wake schedule is across days. The rhythm consistency metric is unique to Polar and based on research linking regular sleep timing to better overall health outcomes.