Understanding resting heart rate

[LindaMtl]

As expected, my resting heart rate goes up significantly when I catch a cold, from RHR of 66 and under to as high as 73.  During such times (this week being one of them), I spend hours of quiet time (reading, tv, puzzles) with heart rate usually 65. I understand RHR is calculated at night. I would like to better understand the variations. My initial thought was RHR is high because I had a restless night and thus a high sleeping heart rate. Except this variation occurs even after a sleep score of 90. Explanations welcome. I am 67, active except when sick, wear a charge 5 and do not have a premium subscription. Thank you!

PS: why can I not post my RHR range? I received this warning « message body contains #-#, which is not permitted in this community. Please remove content before sending your post.

[LZeeW]

@LindaMtl   I hope I can help you with RHR and Fitbit.  First, RHR algorithm is proprietary and Fitbit doesn't share all the details.  Fitbit changed some of the wording in its Help articles over the years.  Fitbit doesn't base your RHR just on sleep.  Some people just can't sleep with a watch on.  The Help article used to say that you could expect a different result if you don't wear your Fitbit to sleep.  It uses heart rate data during other times when there's no accelerometer data to indicated that you are moving.  One detail that isn't shared is how long your need to stop moving before it thinks you are at rest.

You wrote that you don't have Premium.  Your sleeping heart rate and amount of restlessness account for 25% of your sleep score.  It's hard to draw a strong association between sleep score and RHR.

[LindaMtl]

Thank you for trying to help me out. I guess the mystery will remain given the proprietary nature of the algorithm.