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The Apple Watch is one of the most popular smartwatches on the market, and while the Series 11 only offers minor upgrades, these improvements sit on top of an already excellent framework. Despite its widespread appeal, several Apple Watch features might fly under the radar. For example, you might be surprised if your Apple Watch starts glowing red, but it doesn’t mean the device is about to blow up.
If your Apple Watch starts glowing red, specifically the sensor that touches your wrist, that only means the device is measuring your blood oxygen level, specifically when Sleep Focus or Theater Mode is active. This procedure is a “background measurement,” and you should only see it in low-light conditions, such as when you are in bed trying to sleep or in a movie theater. The irony of Apple making the light so noticeable in situations when you don’t want to see it is palpable.
As the Apple Watch has multiple sensors (including a hole that measures water depth), it can do more than just measure your blood oxygen level. Apple Watches can also monitor your heart rate by using green lights. Like with the blood oxygen sensors, this feature will cause the device to glow green, again usually in situations with low ambient illumination.
How to turn blood oxygen level monitoring off
Many doctors will tell you it’s a good idea to keep an eye on your blood oxygen levels. You can do this manually with the Blood Oxygen app, but, as we just went over, your watch might do it automatically, which will bathe your wrist in red light. You can turn it off in the Settings app by selecting “Blood Oxygen,” then toggling off “In Sleep Focus” and/or “In Theater Mode.”
Depending on your health, you might want to keep frequent blood oxygen monitoring active, regardless of any distractions the red light might bring. If you want to examine your blood oxygen measurement history, you can’t do it on your Apple Watch. Instead, you need to have an iPhone synced to the device. From your phone, select the Health app. Then tap on the search function (the magnifying glass). Select “Respiratory,” and finally select “Blood Oxygen.”
If you don’t want to see the red light, you can turn it off, but if you want (or need) to keep an eye on your blood oxygen levels, you will have to put up with the light. We all make sacrifices to stay healthy.
