Missing HRV information

[ac_devel]

Hello all! 
I am downloading vitals data like HR and HRV for some users I manage. 
I noticed that some of them have missing HR variability information. More precisely, the response from the API request is <200 A successful request> but the hrv data is empty. 
Is there any explanation why they have HR information but not HRV?

Thank you in advance!

[GordonFitbit]

Hi @ac_devel 

There are several conditions that need to be met before data can be collected for HRV and some of the other new metrics.  We try to list them all in the endpoint pages in the Additional Information sections.  For HRV, 

1. The data is collected when the user is sleeping
2. The user needs to have a minimum of 3 hours of sleep along with a sleep stages log for that night.
3. The Health Metrics tile in the user's mobile application dashboard needs to be enabled.

If any of these items do not occur, then HRV data will not be collected.   For HRV, a 200 status means the endpoint executed successfully regardless if data exists.

[ac_devel]

I see. 
I am looking at some of the cases and the user has enough sleep on them. I noticed though they have high HR at times so it is possible they move a lot. 

In case the Health metric tile is not active, is data lost forever? 
I thought it was activated all the time. 

[GordonFitbit]

We do not start collecting HRV data until the health metric tile has been activated.   

[ac_devel]

Thank you very much for the clarification.