Facing a legal challenge to its sleep-tracking claims, ŌURA is publishing the science behind its ring, with real stakes for healthy aging.
Millions of people now fall asleep wearing a small titanium ring, trusting that by morning it will have quietly logged how much time they spent in deep sleep, in REM, and simply lying awake staring at the ceiling. That trust is now being tested in court, and ŌURA, the company behind the ring, has responded by doing something companies under legal pressure rarely do: it opened its lab notebook to the public.
ŌURA recently published a lengthy blog post titled Standing Behind Our Science, addressing what it calls a “baseless, opportunistic legal allegation” that consumer wearables, the Oura Ring included, can’t reliably track sleep stages at all [1]. The post is part rebuttal, part science lesson and part reminder of something longevity researchers have been saying for years: the ability to measure your own biology cheaply, continuously and at home is becoming one of the more useful tools ordinary people have for managing how well they age.
The claim ŌURA is fighting
The lawsuit behind all this is a class action filed on 20 August in US District Court in California by the Clarkson Law Firm, on behalf of a Californian named Madison Surber, who paid $513.68 for an Oura ring in 2025 [2]. The complaint’s central argument is blunt: “In reality, Oura rings cannot measure one’s sleep or cycles,” it states. “That’s because sleep happens in the brain, not on one’s finger.”
The suit takes particular aim at ŌURA’s marketing, which promises the ring can measure sleep stages with 95% accuracy. Shireen Clarkson, co-founder of the law firm that filed the case, argues the real number is closer to 50% – in her words, “a coin toss.”
“What the ring does is, it sits on your finger, and it measures heart rate and skin temperature and body movement, and the algorithm spits out an estimate based on those signals about what your sleep stages are,” Clarkson told USA Today. “People are relying on this information for their health, and I think that’s where the danger lies.”
The stakes are sized to match the market. The lawsuit puts the sleep-tracking industry at nearly $7 billion, and says ŌURA sold close to three million rings in 2025 alone, worth more than $1 billion. It seeks to halt what it calls “unlawful and fraudulent” advertising, potentially block further sales and win restitution for customers the suit says overpaid based on claims the ring allegedly can’t back up.
It’s a fair question on its face. Sleep science has, for decades, treated the electroencephalogram – the EEG, which measures brainwaves directly through electrodes on the scalp – as the only real way to know what stage of sleep someone is in. A ring doesn’t touch the brain. So can it actually tell the difference between light sleep and deep sleep or is it just guessing?
ŌURA’s answer, backed by a stack of peer-reviewed validation studies, is that the ring isn’t guessing; it’s using a different, legitimate window into the same underlying process.
“Sleep is not solely a simple state of brain activation,” said Dr Max de Zambotti, director of health science at ŌURA. “Sleep is also a whole-body biobehavioral state, and Oura captures multiple physiological signals simultaneously, such as heart rate, movement and body temperature trends, to determine when someone falls asleep and which sleep stage they’re in.”
That’s worth unpacking, because it’s the whole crux of the dispute. When your brain shifts between sleep stages, your body shifts with it automatically and in patterns that are well documented.
- During deep sleep, your heart rate drops to its lowest point of the night and your breathing turns almost metronomic.
- During REM sleep, when most dreaming happens, your heart rate and breathing become erratic again, almost like you’re awake, even though your muscles go slack.
The Oura ring measures those changes (i.e., heart rate, heart rate variability, breathing patterns, skin temperature and movement) and uses them to infer which stage of sleep you’re likely in, without ever touching your scalp.
What ‘accurate’ actually means here
One useful thing buried in ŌURA’s rebuttal is a plain-language explanation of how sleep-tracking accuracy is even measured because a lawsuit calling it “a coin toss” and a company calling it 95% accurate can’t both be describing the same number.
Here’s the short version. In a validation study, someone sleeps wearing both the ring and a full clinical sleep lab setup. Their night gets chopped into 30-second chunks, roughly 900 of them across eight hours. A trained technician reviews the brain-wave data and labels each chunk – awake, light sleep, deep sleep or REM. The ring does the same, independently, and “accuracy” is simply the percentage where the two agree.
That sounds simple until you realize the benchmark itself is shakier than most people assume. Sleep doesn’t change states in tidy 30-second blocks; it drifts, and a single chunk can carry features of more than one stage. Because of that ambiguity, even two trained technicians scoring the same overnight recording only agree with each other about 83% of the time, according to peer-reviewed estimates ŌURA cites. The “gold standard” itself has a built-in error rate; no device, including another human scorer, would ever hit 100%.
Against that backdrop, ŌURA says its ring reaches 90–96% agreement with lab data on the simpler question of whether someone is asleep or awake, and roughly 76–79% agreement on the harder four-way question of which specific stage someone is in – light, deep, REM, or awake.
In head-to-head university comparisons against five other consumer and research-grade wearables, Oura says it was one of only two devices, the other being a dedicated EEG headband, to reach a level of agreement researchers considered “substantial” rather than merely “moderate.”
None of this makes the ring a diagnostic tool, and Oura is careful to say so. It won’t tell you if you have sleep apnea or clinical insomnia; that still requires an actual sleep lab and a doctor. What it offers instead is something sleep labs generally can’t: nightly, ongoing data from your own bed, gathered over months and years rather than a single unfamiliar night hooked up to wires in a clinic.
Why this fight matters beyond one lawsuit
It would be easy to file this story under corporate damage control and move on. However, there’s a bigger thread running through it that connects directly to the longevity conversation.
Longevity.Technology: For most of medical history, understanding your own aging trajectory meant going to a professional for a snapshot – a single blood draw, a single scan, a single night in a lab. Longevity science has spent the last several years trying to flip that model, building tools that let people track their own biological trends continuously and without a clinic visit. Sleep is one of the clearest examples of why that shift matters: poor sleep quality and disrupted sleep architecture are consistently linked to worse outcomes across cardiovascular health, cognitive function and metabolic health, all central to how well, and how long, people age. A tool that flags when someone’s deep sleep is quietly eroding over months, long before they’d think to book a sleep study, is arguably more useful for healthy aging than one perfect measurement taken once.
That’s precisely why the accuracy of consumer wearables isn’t a trivial argument to have. If the lawsuit succeeds in casting doubt on whether devices like the Oura Ring can be trusted at all, the fallout isn’t just reputational for one company; it could chill an entire category of tools that’s made longitudinal, real-world health tracking accessible to people who will never set foot in a sleep lab.
ŌURA has pushed back on both fronts, in its statement to USA Today and in its own public science post. Responding to the suit, the company said its ring “estimates sleep stages using multiple physiological signals, including heart rate, heart rate variability, movement, breathing patterns and temperature,” and pointed to “well-documented, peer-reviewed independent scientific evidence that sleep stages are associated with distinct, measurable, reproducible changes in physiology.”
The company acknowledged its ring is not “a substitute for a clinical sleep study,” but maintained its methodology “has been validated and compared favorably in multiple studies” against lab-based testing.
“We dispute the allegations in this complaint and intend to defend against them,” ŌURA said. In its science post, the company went further: “We are proud of the work our team of more than 50 MDs and PhDs have undertaken to ensure that Oura is scientifically sound and drives health outcomes, and we will defend our work in the appropriate legal forums.”
A more honest way to talk about wearable data
If there’s a useful takeaway buried in this dispute, it’s more about how people should read the numbers their devices hand them each morning. ŌURA’s own FAQ addresses a familiar experience: the ring says you slept well, but you wake up feeling terrible anyway. That mismatch, the company explains, isn’t evidence the algorithm is broken, but evidence that “accuracy” and “how rested you feel” measure two different things. One reflects your physiology against a clinical benchmark; the other reflects stress, caffeine timing, mood and expectations that no wearable (and no sleep lab) can fully capture.
That matters for anyone using these devices to guide real health decisions. A wearable ring isn’t a mind reader, and it was never meant to replace a doctor. However, as the science behind these tools gets published, peer-reviewed and now argued out in court, the case for treating them as a legitimate piece of the healthy-aging toolkit gets a little stronger.
Image courtesy of ŌURA
[1] https://ouraring.com/blog/how-oura-measures-sleep-and-validates-accuracy/
[2] https://www.usatoday.com/story/money/2026/08/21/oura-rings-sleep-lawsuit/91402959007/
