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aileenchik\/Shutterstock<\/p>\n
It seems like just yesterday that the original Apple Watch hit shelves, and many of the features introduced in 2015 (the Apple Watch’s debut year) are still an integral part of the watchOS experience more than a decade later. Regarded for its many health-tracking features (and other under-the-radar tricks<\/a>), the Apple Watch uses numerous sensors to keep tabs on your reps, calories burned, and other fitness essentials. You may also have noticed a set of green lights on the back of your watch. This is the wearable’s optical heart rate sensor, and it’s completely normal to see the LEDs blinking rapidly; that just means it’s taking a reading.<\/p>\n That green, flashing LED array is actually a medical technology called photoplethysmography (PPG), which is used to monitor how much blood is flowing in and out of a particular area of the body. Because human blood is red, green light is absorbed and reflected without much obstruction. Your Apple Watch then uses that collected data to determine your heart rate<\/a>.<\/p>\n
<\/p>\n You may not see the Apple Watch’s green lights until you’re in the middle of a workout<\/p>\n
i viewfinder\/Shutterstock<\/p>\n The flashing LEDs of your Apple Watch shouldn’t be something you constantly see. Typically, the watch only conducts a PPG scan if you’re in the middle of working out. It’s also supposed to take a reading post-workout and when you’re doing breathing exercises. But if you’re not using your Apple Watch for any of the above, you may find those occasional LEDs to be a nuisance.<\/p>\n Fortunately, it’s pretty easy to disable them: From your Apple Watch, just tap Settings, then Privacy & Security, then Health, followed by Heart Rate, and toggle Heart Rate off. You can follow that same process in reverse to turn the scanner back on. It’s also worth mentioning that if you see the green lights when the Watch isn’t on your wrist, the wearable may erroneously think you’re doing a breathing exercise or working out.<\/p>\n
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