Your skepticism is justified. Oura publish their data, and to quote them: >Oura ring was 96% accurate in detecting sleep compared to polysomnography, 48% accur

Your skepticism is justified. Oura publish their data, and to quote them: >Oura ring was 96% accurate in detecting sleep compared to polysomnography, 48% accurate in detecting wakefulness, 65% agreement in detecting “light sleep,” 51% agreement in detecting “deep sleep” and 61% agreement in detecting REM So it's basically wrong with sleep categorization about half the time.