Oura has built much of its reputation around helping people understand what happens while they sleep. Its rings provide an overall Sleep Score each day, alongside estimates for light, deep, and REM sleep. A new proposed class-action lawsuit is now questioning just how much confidence people should put in those numbers.
Filed on August 20 in the U.S. District Court for the Northern District of California, the complaint accuses Oura of misleading customers by advertising highly accurate sleep-stage tracking despite relying on signals from the wearer’s finger rather than directly measuring brain activity.
Oura has made some big accuracy claims
Oura has previously claimed 79% agreement with gold-standard polysomnography (PSG) when identifying wake, light, deep, and REM sleep. More recently, marketing cited in the complaint claimed 95% sleep-staging accuracy compared with a clinical sleep lab.
The lawsuit argues those numbers may give customers the wrong idea about what the ring can actually measure. A clinical sleep study looks at things such as brain waves, eye movement, and muscle activity. Oura instead estimates sleep stages using heart rate, heart-rate variability, movement, skin temperature, and blood-oxygen trends on newer models.
The complaint also points to a 2025 Nature study involving 45 patients across 45 nights. The Oura Ring correctly identified sleep stages 53.18% of the time, according to the study. It underestimated light sleep by 13.84 minutes and deep sleep by 5.98 minutes, while REM sleep was overestimated by 31.56 minutes.
Why Oura is being taken to court
The case was brought by California resident Madison Surber, who paid $513.68 for an Oura Ring 4 Gold in May 2025. She says Oura’s marketing led her to believe the ring could accurately track her sleep stages and claims she would not have bought it, or would have paid less, if she had known about its limits.
The lawsuit is seeking class-action status, damages, restitution, and changes to Oura’s advertising. Oura has pushed back against the claims. In a statement provided to USA Today, the company said, “We dispute the allegations in this complaint and intend to defend against them.”
For people relying on an Oura Ring every night to understand their sleep, such a large gap between the advertised accuracy and the figure cited in independent research is cause for concern.