Fitbit is working on devices that can diagnose and track sleep apnea

For the past year, Fitbit has been making a concerted push to improve sleep monitoring on its fitness trackers. It debuted sleep stages with its Alta HR and has expanded the feature, along with sleep insights, to other devices like the Fitbit Blaze and Charge 2. But it has much bigger plans for all things sleep related.

Fitbit is now working on devices that can track and diagnose sleep apnea, Conor Heneghan, Fitbit's lead research scientist, revealed in an interview with CNBC. Sleep apnea, which affects 18 million Americans, is a sleep disorder that causes shallow breaths and pauses in breathing while sleeping. It can lead to an increased risk in heart failure, obesity and even cause a stroke.

Essential reading: Why sleep is Fitbit's new obsession

Fitbit's method to diagnose sleep apnea would use heart rate and blood oxygen levels. Specifically, Heneghan indicates the new Fitbit devices could use optical technologies to shine light onto the skin to track blood color. Blood that is highly oxygenated is red, while less oxygenated blood is blue. The sensor would be able to detect when blood oxygen levels lower while someone is sleeping.

"We're leveraging the fact that Fitbit has experience in optical electronics, making them small and power efficient," Heneghan says. He expects the sleep apnea features to come to market within a year, though it's unclear which devices it could come to. It's possible it could be a part of Fitbit's smartwatch.

The company confirmed the CNBC report to Wareable, but declined to share further information at this time.