Red light on sensor watch

[Walker1901]

Hello

this morning I noticed that the sensor lights on the back of the watch were RED and green. Normally it is always green on my watch.

any idea what this red light could be?

[NellyG · Accepted solution]

The modern Fitbits all have red and green lights to detect Heart Rate more accurately. You often cant see the red though, depending on the light at the time. So it sounds as if yours is working correctly!

[Walker1901]

Thanks for the information.

But in 80% of the times I don’t get a sleeping score because of inconsistent heart rate. 

so I am quite surprised that mine is working well

[AdamH0]

The green lights are the heart rate sensor.

The red light is the blood oxygen sensor. However the data from that is only visible in the app to a small subset of users based in the US.

[gresswell]

My fitbit did have the red light until 3 days ago and has now stopped working. I do not shower with the watch on so know it's not due to that. 

[jaenglish1]

I am having the same issues. I have done the hard reboot and the settings restart and nothing has changed. The red light will not go off and my battery drains super fast. I contacted fitbit twice. The first guy walked me through the process and I thought it maybe worked. But I had to call back and the second customer service person was beyond rude and pretty much told me that there was nothing he could do since it was over a year but offer me 25% off for a new device. I have only had my fitbit a year and 4 months. So this is my second one and I'm done. I'm paying for a product that only lasts exactly one year. That is nonsense for the amount I have paid.