California buyer sues Oura, alleging it overstated how accurately its ring's AI tracks sleep stages

California consumer Madison Surber alleges she paid about $514 for an Oura Ring 4 after relying on claims about sleep-stage accuracy. Her proposed class action says Oura's machine-learning algorithm infers sleep stages from peripheral signals. She says she would not have bought it, or paid as much, had she known its limits. Oura disputes this.

What this means for youIf you buy a health gadget, its sleep scores are estimates, not medical measurements. Check what the maker actually claims about accuracy before paying a premium.