Your Oura Ring can’t measure what’s going on in your skull
Oura, maker of the popular smart ring, is facing a class-action lawsuit alleging it misled customers by claiming the device can accurately track sleep stages such as REM, deep and light sleep. The complaint argues this is impossible because the ring cannot directly measure brain waves, and describes its AI-based sleep-stage estimates as no better than a coin flip. The Verge's wearables columnist argues the claim misunderstands how all wearables work, since none measure anything directly beyond motion, and Oura's software instead infers sleep stages from indirect signals.
The columnist notes that heart rate, body temperature and muscle activity all change measurably across sleep stages, giving devices like the Oura Ring legitimate physiological cues to work from, and that Oura has published peer-reviewed validation studies and a supportive op-ed from a sleep researcher in rebuttal. Independent reviews generally find wearables reliable at detecting sleep and wake times, though accuracy for individual sleep stages varies by algorithm and can be thrown off by factors such as sleep position or low battery. The author's broader point is that accuracy debates miss the purpose of such devices, which are meant to reveal long-term lifestyle trends rather than serve as precise diagnostic tools.
- Class-action suit accuses Oura of overstating sleep-stage tracking accuracy
- Suit says rings can't measure brain waves, calls tracking a "coin flip"
- Columnist: wearables infer, don't diagnose; useful for tracking long-term trends
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Sleep has several stages, including REM, light and deep sleep. Brain-wave tests can identify them directly, while consumer wearables such as smart rings estimate them using other signals, including movement, heart rate and body temperature.
Oura makes a ring that tracks sleep and other health measures. The debate centres on how accurately its software can turn those indirect signals into estimates of sleep stages, and on the difference between tracking patterns and diagnosing a medical condition.
Both sides, in good faith
The strongest fair case each way — we don't pick a winner.
The case for
The criticism misunderstands how wearable technology inherently functions. Oura Ring employs indirect physiological signals—heart rate variability, skin temperature and movement patterns—which demonstrably change across different sleep stages, providing legitimate scientific basis for inference. The device has undergone peer-reviewed validation studies and support from published sleep researchers. All consumer wearables, not merely Oura, operate through such indirect measurement and algorithmic interpretation rather than direct brain monitoring. These devices' genuine value lies in identifying long-term patterns and lifestyle trends rather than delivering clinical-grade diagnostic precision.
The case against
The marketing surrounding Oura Ring creates misleading consumer expectations by implying it can reliably measure or track individual sleep stages when the device cannot access the electrical brain activity that defines them. Whilst indirect physiological signals correlate with sleep stages, this inference is substantially less accurate than direct measurement and varies significantly based on individual factors, sleep position and device state. Claims suggesting reliable sleep-stage tracking may overstate the device's actual capability, misleading consumers into believing they are obtaining medical-grade sleep analysis rather than rough approximations, raising legitimate consumer protection concerns about whether marketing language matches realistic performance.