Health and fitness wearables are experiencing something of a renaissance at the moment, like the Oura Ring and smart watches. In the case of Oura, it's a sleek, lightweight smart ring capable of tracking all kinds of health metrics, from sleep to heart rate to temperature. In fact, it includes so many advanced features, sometimes it can be a challenge to keep track of what the various indicators actually mean — including a red light.
A red light on a health tracking device may seem alarming, but don't worry: If you grabbed an Oura Ring 4, one of our favorite smart rings, and it's displaying a red light, that just means it's actively measuring your blood oxygen levels (SpO2) while you're asleep. The sensor keeps an eye on variations in those levels, which can be important indicators for your overall health. Most people's blood oxygen saturation level should measure between 95% and 100%; a reading too far below that may indicate a potential issue. Be aware that this feature isn't available on Gen2 or older Oura Rings.
How the Oura Ring detects blood oxygen levels
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While you're asleep, the Oura Ring sends pulses of red and infrared light into your finger by way of it's LEDs. Highly oxygenated blood reflects more red light than infrared light; inversely, low blood oxygenation levels mean more infrared light is reflected. The ring measures this and reports the data in the Oura app. You can find it on the Sleep screen, though you'll want to ensure that your Oura Ring's sleep tracking is working correctly first.
You can see your Average Blood Oxygen score, which is the percentage of oxygen in your blood over three hours of sleeping, as well as a graph of your Breathing Regularity. This will give you a sense of any irregularities in blood oxygen levels over time, and is not the same as respiratory rate, which is based on breaths per minute.
Normally, you won't see those red LEDs light up during the day, but you may catch a glimpse of them anytime the ring detects sleeping. If you're relaxing and your heart rate, BPM, and movement hit low levels, the Oura ring may think you've fallen asleep and begin reading your SpO2.
How to use Oura's blood oxygen sensing features
Tracking of Breathing Regularity and Average Blood Oxygen needs to be manually enabled before the Oura ring will start measuring while you sleep. To do so, find the hamburger menu in the Oura App and select Blood Oxygen Sensing, then tap the button and toggle it on. To activate it, your ring will need to be connected to the app via Bluetooth. Next time you're asleep for more than three hours, your scores should pop up on the app's Sleep screen.
Breathing Regularity shows up in the app as a color-coded timeline with an optimal rating displaying no major variations. A good rating will display as dark blue vertical lines, while fair is rendered in light blue. Frequent variations in your blood oxygen levels, which show up as white lines, may indicate an issue with your breathing or oxygenation, so you'll want to pay special attention in this case. There are also suggestions on how to improve your breathing regularity that can be accessed by tapping the information icon.