Your Apple Watch sensor emits a red light when it is checking your blood oxygen saturation levels, which are a measure of heart and lung function.
Strapping an Apple Watch to your wrist is more than just a fashion statement, though there are a slew of different stylish bands out there made out of everything from sensible leather to funky beads. These devices also provide hands-free access to phone notifications, encourage wearers to stay active, and track levels of activity during work-outs. If you opt to add cellular support to your Apple Watch, you can also answer a call on the device, even when your phone isn’t nearby. Additionally, there are lots of things the Apple Watch can do without a phone at all, like stream music, track your sleep, and set alarms. It’s a little device that does a lot, but have you ever noticed an odd red glow coming from the watch now and then?
If you have an Apple Watch from Series 6 or later, you’ve likely spotted a red or green glow coming from the bottom of the device. A green glow means your smartwatch is checking your heart rate, which is a popular feature. A red glow indicates that the Apple gadget is checking your blood oxygen saturation levels.
