Smart ring maker Oura is facing a proposed class action lawsuit accusing it of deceiving consumers about the accuracy of its sleep tracking features. The lawsuit, filed Thursday by Clarkson Law Firm in San Francisco, alleges that Oura rings can't actually measure the physiological signals needed to assess sleep quality or determine sleep stages. Instead, they rely on AI-generated estimates that have "a coin flip's chance of being correct," according to the complaint.

The suit follows years of users taking to the internet to vent about the ring's sleep accuracy, with some saying they felt they slept poorly but were told their sleep was optimal. Others expressed doubts about the device's ability to monitor and detect sleep cycles.

The complaint claims Oura sold rings priced at $300 and up by advertising that they could see what only a hospital sleep lab can see, including the four stages of sleep. "Oura did not just claim to measure a heartbeat or a temperature, but the exact stage of sleep the wearer is in - which in reality requires electrodes in the scalp and sensors on the eyes, as only a hospital or other clinical setting can do," the complaint reads. Despite this, Oura marketed its ring as "built for accuracy" and offering "unparalleled accuracy," claiming 79% accuracy in measurements and more recently 95% sleep-staging accuracy compared with clinical sleep labs.

The complaint also notes that "sleep happens in the brain, not on one's finger." Oura did not immediately respond to TechCrunch's request for comment.

Ryan Clarkson, co-founder and managing partner at Clarkson Law Firm, said in a press release: "When people rely on a device to guide decisions about their health, misinformation cannot be tolerated. Oura users trust that the numbers on their screen reflect reality. People structure their days, interpret the way they feel, and design their lives around inaccurate figures spit out by these devices. Marketing an inaccurate sleep tracker as precise and reliable is dangerous because people believe it - and change their behavior accordingly."

The lawsuit seeks to stop Oura from falsely advertising its wearables, injunctive relief to prevent future misrepresentation, and restitution for consumers who purchased the products based on those allegedly false claims.