Why Does A Smartwatch Flashes Green Again and Again?

If you are a smartwatch user, you must have noticed a green light that flashes from time to time.

Or when you switch to the heart rate interface test at the end of the bracelet, the bottom of the bracelet will also begin to flash green.

Like many people, you must also question, “Why does a smartwatch flash green”? If yes, so we have answered this question in this article. Have a look!

Why Does A Smartwatch Blinks Green?

The reason behind this is that the smartwatches use PhotoPlethysmoGraphy (PPG) to monitor your heart rate.

The light flashes on the blood pulses, veins, and arteries under your skin, and a light-sensitive photodiode measure the amount of green light absorbed. The amount of light absorbed at a given time determines your heart rate.

The principle behind the blinking of the green light is that our blood color is red, so it reflects the red light and absorbs the green light.

How The Green Light Monitors Heart Rate?

The green LED lamp of the smartwatch is used in conjunction with the photoelectric sensor to emit green light into the blood vessel.

This helps in the detection of the amount of blood flowing through the wrist for 24 hours, and thereby it obtains your heart rate information according to the change in light intensity of your watch.

Due to the reason mentioned above, the green light behind the smartwatch performs the heart monitoring function.


You must have this question in your mind that, “Why, not red light or other colors of light? So the answer is that the human blood color is red, and it absorbs a large number of green light.

Due to this absorption of green light, it reflects the red light and also other colors of light. Because of this reason, a smartwatch uses a green light for heart rate monitoring.


When you measure the heart rate, so must keep in mind that your body should be in rest condition.

Secondly, don’t leave a space between your watch and your arm. Also, don’t shake your arm during the test.


The green light source of your smartwatch belongs to the visible light. Therefore, it is not different from the natural green light and is harmless to the human skin.

The blood monitoring method is only collected by illuminating, so there is no harm. You can use the heart rate monitoring function without any hesitation.

Can You Stop Blinking Of This Green Light?

If you don’t want it to light up, you can turn off the Automatic Heart Rate Monitor on the WoFit Assistant or H Band App.

For Apple Watch

If you are using the Apple Watch and want to turn it off, you have to turn off the heart rate monitor.

Now you have to open the Watch App on your iPhone and tap “My Watch” down at the bottom of the screen, then tap “Privacy.” Then, finally, flip the Heart Rate switch. And you’re done.

For Fitbit Watch: 

If you are using a Fitbit watch, you have to go to Fitbit>Your Watch (top-right)>Heart Rate and set it to Off/On/Auto. You’re done.

But if you turn it off, this means that it would not track your heart rate.


If you want accurate test results, you have to look at these factors that can affect your test results.

  • Weather can affect your test results. Your pulse may go up a bit in higher temperatures and humidity levels.
  • Stress, emotions, and anxiety can raise your heart rate.
  • Medications, nicotine and, caffeine can affect your test results.

Final Words

By reading the answers to all the questions mentioned above, you must now familiar with the flashing of the green light, its reason for blinking, its function, and its effect on the skin.

So, you must not be confused about this green light because all the fitness trackers that support the heart monitoring feature have this green light. And this light monitors the heart rate in those trackers.

You also must not be curious about the effects of this light, and you can use its function without any hesitation because it does not affect your skin and body.

Check the Best Fitness Tracker For Spinning: Here



Leave a Reply