https://www.theverge.com/2017/8/30/16227040/fitbit-sleep-apnea-tracking-ionic-smartwatch-sensors

Fitbit, the digital health company whose wristbands have become synonymous with the whole activity-tracking movement, is trying to bring its health monitoring game to the next level — by focusing on a sleep disorder that affects millions of Americans.

Fitbit has said that it’s working with a combination of optical sensors and machine learning tools in its R&D labs to potentially address a condition in which people stop breathing in their sleep, called sleep apnea. Its new Ionic smartwatch, which was announced earlier this week, has a new kind of optical sensor that Fitbit says is the first step towards gathering the data that would help it accurately identify apnea.