The Oura Ring 4 Can Tell You How You Slept or Predict a Cold. Is It Worth It?

As a writer on Wirecutter’s sleep team, I test mattresses and gear related to getting a better night’s sleep, including wearable sleep trackers, mattress toppers, and body pillows.

For this guide:

• I interviewed Seema Khosla, MD, medical director at the North Dakota Center for Sleep, about the general accuracy and usefulness of sleep trackers.
• I interviewed Oura representatives, including product manager Caroline Kryder; Rebecca Robbins, PhD, a member of Oura’s Medical Advisory Board and instructor of social and behavioral sciences at Harvard School of Public Health; and Jason Russell, the VP of consumer software product at Oura.
• I wore a fourth-generation Oura Ring for six months, tracking my sleep and health data almost continuously with that model after testing the Gen3 for almost a year.
• Like all Wirecutter journalists, I review and test products with complete editorial independence. I’m never made aware of any business implications of my editorial recommendations. Read more about our editorial standards.
• I chose the experts I consulted for this article for their knowledge and independence. For transparency and accuracy, we have disclosed any affiliations that experts have with companies mentioned in this article.

Before the Oura Ring, most health- and fitness-tracking wearables were bulky wristwatches, Fitbit and Apple Watch models chief among them. The titanium, wedding-band-like Oura Ring was the first of its kind: sleek, discreet, but with all the health tracking of its competitors.

The Oura Ring 4, the latest-generation ring, works similarly to its predecessor, the Gen3. The device shines light beams (infrared, red, and green LED) through your skin to measure your respiratory rate, heart rate, HRV, blood-oxygen levels, and body temperature. The Oura app then synthesizes that data into three scores, between 0 and 100, that greet you at the top of the homepage: Sleep (how well you slept), Activity (which you can edit to include heart rate and stress), and Readiness (how prepared your body is to take on the day).

With the latest version, Oura has significantly increased the number of sensor pathways in the ring: Whereas the Gen3 had eight, the Oura Ring 4 has 18.

Those additional sensor pathways improve the app’s core insights and help inform new metrics such as Stress Resilience, Symptom Radar, nighttime movement, fertility tracking, and menstrual tracking. An accelerometer still logs your activity and movement but is now able to track your inactivity as well.

The way the Oura Ring 4 calculates your Sleep score has not changed from the previous version. It does so by analyzing your total sleep time (including naps), your sleep efficiency (time asleep versus time awake), and your time spent in REM sleep and deep sleep (the most restorative type of sleep). It also considers your sleep latency (how long you take to fall asleep) and how often you toss and turn during the night.

In addition, the Oura app determines your chronotype (effectively, whether you’re a morning person or a night owl) and body clock (your optimal sleep schedule) after you’ve used the device for 90 days.

It calculates the Activity score by measuring how much you moved around during the previous day, and the score increases or decreases based on how much you continue to move. The score includes how well you’ve heeded the app’s reminders to move (which it issues if it deems that you’ve been sitting for too long), how frequently you engage in activity of medium to high intensity, and how often you meet your fitness goals.

Your Activity score rises the more consistent you are with your exercise, or if you’re able to meet your personalized baseline activity goal for each day, which is based on active calorie burn (the kilocalories you burn during daily movement and exercise). The app determines your baseline activity goal from specs such as your age, your height, and your daily Readiness score. For example, my baseline activity goal is 400 calories (my step goal is 10,000). But you can edit your baseline and step goals in the app’s Activity tab.

Your Readiness score combines elements of your Sleep and Activity scores to calculate your readiness for the day. In addition to sleep and activity data, this score considers your HRV (comparing your current week’s trend against your three-month average) and skin temperature (fluctuations in temperature could indicate illness, for example, or that menstruation will begin soon). The Readiness score also relies on data from your inactivity and recovery index (how long your heart rate takes to stabilize during the night), a new metric on the Oura Ring 4.

Scoring 85 or higher out of 100 on each metric is considered optimal; if you happen to score less, the Oura app gives you guidance on what to prioritize (more rest, intentional movement, or even taking time to daydream) without any judgy finger-wagging. You can share and compare your scores with friends via Oura’s Circles feature.

Oura has improved its tracker’s sensing accuracy. The most notable upgrade of the fourth-generation ring is its “smart sensing” algorithm. The sensors are now recessed and asymmetrically positioned, in contrast to the three bumps in the Gen3. The smart sensing algorithm chooses which sensors to pull data from at any given moment, improving the accuracy of its findings. It essentially finds the path of least resistance — through your unique finger size, blood vessels, or skin tone — to deliver constant data throughout the day.

The app’s data is easier to read and digest. Oura’s app, like many fitness apps, throws a lot of data at you in the form of color-coded charts and graphs. But unlike the past iteration of its software, the updated Oura app, accessible to both Gen3 and 4 wearers, includes explainers for anything you may not understand.

The app also has Trends and Reports tabs that help to synthesize all of your collected data: The Trends tab’s graphs show you how your Sleep, Activity, Readiness, and Stress scores have averaged over a week. The Reports tab gives you that same data in monthly, quarterly, and yearly intervals.

The Oura app no longer requires you to tap each score to see its details. Instead you can see your daily scores, your health metrics, and your health trends in three separate tabs: Today, Vitals, and My Health. This arrangement made it much easier for me to interpret my data at a glance.

It’s lighter, sleeker, and more comfortable. The Oura Ring looks and feels like a piece of jewelry, akin to a wide wedding band. The fourth-generation version comes only in the “smooth” style, whereas the Gen3 came in both “smooth” and “heritage,” a flat design with squared-off edges. But it’s available in multiple finishes — silver, black, matte black, stealth, gold, and rose gold — so it can fit seamlessly with your personal style. I have tested the gold and rose gold finishes and found them understated yet chic.

Thanks to the lighter, smoother design, the new ring feels more comfortable while I’m doing everyday things (such as shaking hands) and is less disruptive while I’m sleeping. I used to take off my Oura Ring Gen3, for example, when I was cooking or doing my hair, because the thickness of the ring made gripping something like a knife or a hairbrush difficult.

The Oura Ring is water-resistant, too, and it can withstand temperatures from 14 °F to 129 °F. However, I prefer to take it off while washing my hands, showering, or swimming.

Oura has also expanded the size range, which now extends from 4 to 15 (in contrast to the Gen3’s range of sizes 6 to 13).

The battery life has been improved. During our previous testing, the Oura Ring Gen3 needed recharging every five to seven days, but the Oura Ring 4’s hardware, partly thanks to the automatic adjustment of the LED brightness, can last up to eight days before needing to recharge. (Note: The Oura Ring’s blood-oxygen monitoring can cause the battery to drain significantly faster, but you can turn that function off.)

Some Gen3 wearers have raised concerns on Reddit about the battery’s dying faster over time, to the point where it needs recharging every 24 hours. I contacted Oura about this issue, and representatives said that the company will replace your Gen3 ring if you have battery issues, even if it is outside of Oura’s one-year warranty. We did not encounter this issue with the Oura Ring 4.

Its HRV tracking and Symptom Radar feature are impressively accurate. The Oura Ring was one of the first smart rings to measure HRV, or the regularity (or irregularity) of the time between pulses. High HRV is generally good; it suggests you’re relaxed and well. Low HRV (when the time between heartbeats is consistent, without much variability) may be associated with physical or emotional stress.

When I tested the Gen3, the ring was able to detect my very low HRV while I grieved a death in the family. With the Oura Ring 4, the HRV sensors allowed the app’s Stress Resilience feature to accurately measure my stress levels during exhausting travel days and high-intensity exercise classes.

Oura’s Symptom Radar is calculated from biometrics such as body temperature, respiratory rate, resting heart rate, and HRV. It notifies you of potential strain at three severity levels: no signs, minor signs (small indicators that something may be straining your body), and major signs (stronger indicators).

Anecdotally, the Symptom Radar feature alerted me that my “biometrics showed major signs of something straining” my body long before I knew anything was wrong. Lo and behold, hours later I couldn’t stop sneezing and had to nurse a cold soon after.

(Note that Oura says that the Symptom Radar feature may not work with preexisting conditions that already cause elevated biometrics. For instance, Oura’s algorithm may accurately detect real change in the body that it would identify with illness when the symptoms may actually be reflecting an underlying condition, such as pregnancy.)

Its recommendations are personalized, without being pushy. The Oura app gives suggestions for steps that you can take to be more active, to rest more, or to sleep better (and thus improve your three scores). I found that Oura’s recommendations were more personalized and more achievable than those of some other sleep tracker apps I tested. For example, instead of repeatedly telling me to be in bed by 10 p.m. (something that was never going to happen), the app adapted to my sleep habits and recommended a new, more realistic bedtime and wake-up goal for my “chronotype.”

If I woke up feeling groggy, the app might suggest that I enter Rest Mode. Caroline Kryder, product manager and women’s health lead at Oura, explained that the app will encourage Rest Mode if your temperature is elevated, your heart rate looks off, or your body is showing signs of strain.

I took it as a delightful cue to head back to Wordle or, even better, go for a nap. Then, when the app had noted that I had logged some downtime, it would nudge me to put my newfound energy into action — in other words, to take a walk. After a while, I started feeling like I had developed better habits with these bits of gentle encouragement, rather than scolding.

It regularly tracks rest as sleep. The Oura Ring 4’s smart-sensing capabilities often mistake restful activities, such as doing computer work, watching a movie, or hanging out at home, as a “nap” when it prompts you to input your activity. One colleague who is also testing the Oura Ring 4 noted that the ring logs her wake-up time as later than accurate.

However, Oura has improved the fitness-tracking capabilities of its software, making it capable of identifying more activities while tracking at a continuous rate (something we had issues with when we tested the Gen3 with an older version of the app).

My colleague wore her Oura Ring while swimming, and it correctly logged her activity as such. It also noted her elevated heart rate while she was in the sauna. Oura’s Automatic Activity Detection tends to recognize cardio better than other forms of exercise or movement. But if the tracker does log the wrong exercise, it will learn from its mistake either on its own or after you go in and edit your activity retroactively. For example, my colleague has noticed that her ring has improved at differentiating walking from “housework” without her having to tell it so.

The Oura Ring also integrates with the Strava fitness-tracking app and social media platform, but it’s not seamless: You have to be signed in to the Strava app and select the activity you want to track.

It’s expensive, and it’s better with a monthly subscription. The Oura Ring costs $350 to $550, depending on the design and finish (the technology and features are the same in all models). The app used to be free, and it still is for the first month for new users, but now it requires a $6 monthly subscription (or $70 if you pay up front for a year) for you to access most of Oura’s data and analysis. The cost of the ring and subscription are eligible for reimbursement through a flexible spending account (FSA) or health spending account (HSA).

And it’s still easy to lose. The Oura app for iOS has a Find My Ring feature, which shows the last location at which your Oura Ring connected to your phone. As someone who looks at the Oura app only maybe twice a day, this feature is hardly helpful for me. The last time I couldn’t find my ring while at home, Find My Ring told me it was at Wirecutter’s office — when in fact, it was at home on the bathroom sink, where I tend to leave everything.

The Oura Ring is an effective and easy-to-use health tracker, and it’s our top pick specifically for sleep tracking. But it isn’t for everyone. If you’re already anxious or hypervigilant about your health, a tracker like the Oura Ring might just exacerbate your anxiety.

You can also get some of the same basic functionality out of a much cheaper fitness tracker, such as the Fitbit Inspire 3, our top-pick fitness tracker. If you go this route, be prepared to miss out on accurately tracked sleep and wake times, the ability to easily access your sleep data in an app, or the general comfort of wearing a lightweight ring to bed.

If you like the idea of an unassuming accessory gentle-parenting you into a more restorative sleep, tracking your health metrics in order to alert you if you’re getting ill, aiding in fertility tracking, or helping you stay on top of your fitness goals, go ahead and put a ring on it.

This article was edited by Christina Colizza and Marguerite Preston.