I realize that this question has been asked in the community forums before, (see https://community.fitbit.com/t5/Charge-HR/Sleep-and-Heart-Rate-DON-T-Communicate/m-p/928479 and https://community.fitbit.com/t5/Charge-HR/Charge-HR-improve-sleep-tracking/m-p/629951), but they were not answered by a Fitbit moderator. This is an important question, both for people who bought the ChargeHR/Surge for the heart rate monitor and for researchers, like myself, using these trackers in research. Heart rate is known to improve sleep estimation over regular actigraphy (accelerometer-based sleep tracking), and since these devices already have the heart rate, it would make sense for them to use it. Unfortunately, there is no mention of these trackers using heart rate in sleep, as one of the posts I linked to states.
So, to be clear, if I use sleep tracking in my research can I assume that the ChargeHR/Surge devices use heart rate as well as the normal Fitbit sleep tracking algorithms, in order to improve estimated sleep? Or is sleep estimated only from the accelerometer like the non-heartrate devices?
