Oura, the smart ring company that recently entered the South Korean market, is facing a class-action lawsuit in the United States over allegations of false advertising regarding its sleep-tracking accuracy.

According to the U.S. District Court for the Northern District of California on the 21st (local time), Clarkson Law Firm filed the class-action lawsuit against Oura, representing California resident Madison Server as the lead plaintiff.

In the complaint, Server stated that she purchased and used an Oura product in May of last year, but suffered damages as the device failed to accurately measure sleep duration, the number of awakenings, and sleep quality.

Oura has previously advertised through commercials and promotional materials that its products achieve a 79% accuracy rate in measuring sleep stages, with the latest models reaching up to 95% accuracy.

To boost the credibility of these claims, the company also touted that an in-house scientific team consisting of more than 25 PhD-level researchers had verified the products.

However, the plaintiff pointed out that Oura's smart ring products lack the capability to directly detect physiological signals essential for measuring sleep stages, such as brainwaves, eye movements, and jaw muscle activity, arguing that the advertising claims were exaggerated.

The plaintiff criticized that while Oura acknowledged this fact in its technical documentation by noting potential discrepancies with polysomnography (PSG) due to its inability to measure brainwaves or eye movements, it simultaneously ran contradictory external advertisements.

Citing a paper published in the academic journal Nature last year which reported that the sleep-stage accuracy of Oura rings is only 53.18%, the plaintiff argued that the claimed "unmatched accuracy" is effectively at the level of a coin toss.

The plaintiff also emphasized that competing smart ring brands such as Slip-on and Circle completely refrain from such exaggerated advertising.

In the lawsuit, the plaintiff demanded a complete halt to the false marketing, as well as consumer refunds and compensation for the price premiums charged based on the deceptive advertisements.

Oura did not respond to a request for comment from the IT specialized media outlet TechCrunch regarding the lawsuit.

Founded in Finland in 2013 and currently headquartered in San Francisco, USA, Oura was valued at 11 billion dollars (approx. 15.2 trillion won) in an investment round in October of last year, and surpassed 1 billion dollars in annual revenue after selling 3 million smart rings last year.

Oura is pursuing an initial public offering (IPO), having confidentially submitted its IPO application to the U.S. Securities and Exchange Commission (SEC) in May, and expanded into the South Korean market on the 18th.

(Photo: AP, Yonhap News)