The biggest health-related features of the Apple Watch are known to track your daily activity, improve your workouts, and measure your heart rate, but have you ever wondered how the Apple Watch measures your heart rate? This is done by the flashing green lights that you see every now and then, you must have seen them flashing some green lights on the underside of your hand, you know what these lights are and how Apple uses them to measure your heart rate.
What do the green lights on the Apple Watch mean
The optical heart sensor in the Apple Watch uses something called photoimaging, and this method relies on the fact that blood is red, as blood reflects red light and absorbs green light.
For this reason, the Apple Watch uses an array of green LEDs with more than one photosensitive LED to detect the amount of blood flowing through the veins on your wrist, and the faster your heart beats, the more blood flows and absorbs green light.
The Apple Watch flashes green lights hundreds of times a second to count your heart rate every minute, and this helps the Apple Watch determine your heart rate.
How to turn off the green lights on the Apple Watch
There is no harm in leaving the green lights on the Apple Watch to do its job perfectly. But, if you want to turn off these lights, keep in mind that this means that you will not be able to automatically measure your heart rate using the watch again, unless you do it manually as will be shown.
How to disable heart rate on Apple Watch
◉ Press the Digital Crown.
◉ Go to Settings.
◉ Scroll down and go to Privacy.
◉ Scroll down again and select Health.
◉ Tap Heart rate, then turn off Heart rate.
How to disable heart rate on iPhone
◉ Open the Watch app on the iPhone.
◉ Scroll down and tap Privacy.
◉ Then turn off the heart rate.
Note that even if you disable this feature, you will still be able to measure your heart rate manually, all you have to do is go to Heart Rate, and the Apple Watch will start measuring your heart rate.
What about the red lights on the Apple Watch?
If you have a fairly new Apple Watch, specifically an Apple Watch 6 or 7, you've likely also seen some red lights on the underside of your hands.
The Apple Watch uses a combination of red, green, and infrared LEDs and shines them on your wrist, then more than one LED measures how much light is reflected back.
The Apple Watch then calculates the data to calculate the color of the blood. The color is used to determine the level of oxygen in the blood. Light red blood means that it contains more oxygen, while dark red blood contains less oxygen.
How to turn off the red lights on the Apple Watch
Just like the heart rate lights, there's no good reason to disable the blood oxygen scanner, but if the red lights bother you, you can easily turn them off.
How to disable blood oxygen measurement on the Apple Watch
◉ Press your Digital Crown.
◉ Go to Settings.
◉ Scroll down and go to Blood Oxygen or blood oxygen measurements and disable it.
◉ You can also scroll down and disable background measurements if you just want to disable it during sleep focus mode or in theater mode.
How to disable the measurement of oxygen in the blood on the iPhone
◉ Open the watch app.
◉ Scroll down and select Blood Oxygen Measurements, then disable it.
◉ You can also scroll down and disable background measurements if you just want to disable it during sleep focus mode or in theater mode.
Depending on what you choose, you won't be able to measure your blood oxygen at all, and you'll need to enable this feature if you want to use it again.
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