Does the Oura Ring Really Just Guess Your Sleep Quality Score?
Oura is currently facing legal action over claims that its ring measures sleep. Both the law firm that filed the class action lawsuit and Oura itself have released statements outlining their views on the matter, and I’ll be reviewing them in detail today. I also want to address the central question: how much can we trust our wearables when it comes to sleep data?
What’s happening with the lawsuit against Oura?
So, first, about the lawsuit. It’s a class action lawsuit filed by the Clarkson Law Firm in California on behalf of Madison Surber, who purchased the Oura ring. The lawsuit states: “At the time of purchase, Plaintiff did not know that the disputed claims were false, that is, that the product could not accurately and definitively measure sleep stages.” The full lawsuit can be read here .
The law firm’s press release summarizes the issue as follows: “The product fails to measure any of the physiological signals necessary to determine sleep quality or sleep stages. Instead, it provides only AI-generated predictions, which, according to the complaint, are no more reliable than a coin flip.”
Following the lawsuit, Oura published a blog post titled “We Stand by Our Scientific Research,” which you can read here . It states: “The recent baseless, opportunistic legal accusation seeks to discredit sleep tracking and assessment methods using consumer wearables, including the Oura ring. We dispute these accusations and firmly defend our research and its accuracy.”
Beyond the lawsuit being filed and both sides stating their positions, nothing official has happened yet, and it may be some time before we hear anything else. The case hasn’t reached trial yet, no ruling has been issued, and Oura rings will continue to be sold for the foreseeable future.
It’s also worth remembering that many lawsuits don’t even make it to court; the parties often reach private settlements, and we may or may not know the terms of those settlements. Sometimes, a lawsuit is filed with sensational claims, even if the plaintiff doesn’t expect to ultimately win. I’m not a lawyer and am not qualified to judge who is likely to win this case or why it was filed. However, I can discuss whether it’s reasonable to expect wearables to adequately track our sleep.
Why you shouldn’t take sleep data too seriously.
I write about fitness technology and constantly encounter a fundamental problem: companies force their devices to provide numerical data, and users of these devices want to know how “accurate” this data is. I try to answer this question, but it’s often impossible.
Here’s why. First, only a measurement can be accurate: for example, “How many beats per minute is my heart?” (Which, by the way, I can check when writing about devices, as you may have noticed ). If this measurement matches a reference value (ideally, based on several tests over a period of time and involving different people), we can judge its accuracy.
But most of the data reported by wearables isn’t strictly speaking a measurement. It can be calculated based on other data. The time you spend asleep is calculated based on your sleep start and end times, and the algorithm has to “decide” when these events occurred. Similarly, even for something as simple as counting steps, the device must “know” which movement should be counted as a step. This is why we can get different step counts from different devices. And since watches only have access to wrist motion data, they don’t know what your feet are doing. Indoor mileage is also an estimate for the same reasons.
Even further removed from these statistics are the scores and their interpretations. Some of them are clearly made up: a sleep score of “79” doesn’t correspond to anything a scientist could measure in a lab. But sleep stages are also included in this category. When Oura tells me I had 51 minutes of REM sleep last night, it doesn’t know that; it’s simply processing the available data and making its best estimate. I’ve often told you guys not to get too caught up in sleep stages and instead focus on overall sleep duration and real-world factors like how tired you feel during the day. My colleague Meredith Dietz came to a similar conclusion after interviewing sleep scientists for this study on why sleep scores are much less useful than you think .
What does the Oura ring (or any other wearable device) really know about your sleep?
Let’s get back to basics. What happens inside the ring itself? The Oura ring can shine red and green (as well as infrared) LEDs onto your skin, and its sensors detect the reflections of this light to get a fairly accurate picture of your heart rate and a rough estimate of your blood oxygen levels. The ring is equipped with motion sensors, so it can detect when you (or at least your finger) are moving. It also has a skin temperature sensor.
That’s all there is to measurements in the strict sense of the word. Based on your heart rate fluctuations, Oura can calculate your respiratory rate and heart rate variability (HRV) . Using accelerometer data, it can calculate the time it believes you’re lying perfectly still. Oura has written here about what it measures and what it calculates or infers from these measurements. This article focuses on the Oura Ring 4 (which is also mentioned in the lawsuit), but you can expect most smart rings and other wearables to work similarly.
So, the lawsuit is technically correct in claiming that Oura doesn’t actually know your sleep stages. But Oura could successfully argue that its accuracy is as high as possible for a wearable device.
We’ll likely never know how accurate the sleep data collected from wearables is.
One of the allegations in the lawsuit struck me as interesting: “Plaintiff has no personal knowledge of the mechanism or science underlying the products’ promised sleep-tracking features. … Plaintiff has had no way, and still has no way, to determine whether the challenged product claims were, or continue to be, true.”
Wearable device companies don’t publish their algorithms. (There may be exceptions to this rule, but I can’t think of any.) Neither the device itself nor the software that interprets its data are thoroughly publicly tested for accuracy or reliability before the device goes to market.
That’s why tech journalists like me have to settle for N-of-1 testing: I, as one person, run a few runs and report the results. I, as one person, sleep for several nights, comparing readings from multiple devices. I can’t rent out a sleep lab for every device review, and if I could, ideally I’d enlist several hundred friends and spend a significant amount of research funds on a team of scientists to thoroughly analyze the results. But that’s simply not in Lifehacker’s budget. Ironically, tech journalists like me are the first—and in some cases, the only—people conducting in-depth, independent tests of wearables.
Sometimes scientists conduct full-scale studies, especially on popular devices or devices that have potential clinical or research applications. I appreciate these studies, but they’re not done often enough to be useful to the average person who wants to know if a new device actually does what it claims. By the time an article about how the Garmin Fenix 6 measures heart rate during sleep comes out, Garmin is already selling the Fenix 8. And by the time you hear about it—maybe today?—we’ll have already moved on to the Fenix 9 .
The best and worst moments of the trial that I think are worth reflecting on.
In the law firm’s press release, several attorneys emphasized that clients make decisions in their daily lives based on information received from wearables. This is true for all wearables, not just Oura, and I think it’s a fair point. We’re probably overrelying on data that shouldn’t be trusted.
I don’t find the lawsuit’s claim that “sleep occurs in the brain, not in the finger, convincing. It’s determined by electrical activity in the brain, eye movements, muscle tone, and other signals…” That quote almost convinced me in the first half, but sleep isn’t determined by EEG readings or anything like that. It’s measured that way in a lab.
A sleep researcher tries to eavesdrop on what’s going on inside your body, and to that end, scientists have described sleep stages based on these signals. But sleep itself remains a mystery to science. Professional equipment likely offers a better understanding of what’s going on than a home sleep monitor, but both merely describe the external signs of an incomprehensible internal process.
In its blog post “Supporting Our Science,” Oura notes that several scientific and medical groups have published peer-reviewed papers based on sleep data collected by Oura devices. I commend Oura for encouraging research groups to study their devices. However, many familiar challenges arise when reviewing these studies.
For example, the most recent study from 2024 compares the third-generation Oura ring (two models old) with the Fitbit Sense 2 and Apple Watch Series 8—all fairly outdated models at this point. One of the authors is a consultant for Oura and serves on its medical advisory board. And I don’t find the results particularly impressive; they report a sensitivity of 75% or higher in detecting sleep stages, which may be slightly better than other devices, but still confirms my long-held belief that you shouldn’t put too much trust in the claims of any wearable device about the stages or “quality” of your sleep.
Here’s what I’ve come to after reading both sides’ claims: a smart ring (or watch) is a tool that can communicate its measurements, assessments, and conclusions. Some of these may be useful. But neither can ever guarantee accuracy. Perhaps we should all forget about the pursuit of accuracy and focus more on good old-fashioned things, like maintaining a good bedtime routine .