Oura is a Finnish company known for its screenless smart ring. Worn day and night, Oura tracks sleep, recovery, activity and health trends. The app combines these signals into Sleep, Readiness and Activity scores and provides personal guidance.

How it works
Green, red and infrared lights measure blood flow and oxygen changes in the finger, while temperature sensors track skin trends. Motion sensors record movement and activity. Software estimates heart rate, heart rate variability, breathing, sleep timing and stages, and adapts sensing as the ring shifts.

Key considerations
A close fit is essential, and cold hands, movement and wear gaps can affect data. Sleep stages and readiness are algorithmic estimates, while cycle insights do not provide contraception. Many app features require an ongoing membership after a trial.