That is interesting. I haven't used any of the Apple watches so I can't speak to the effectiveness of its HRV calculations for me. One of the Oura C-level guys spoke in a podcast that doing those kinds of calculations isn't as reliable because of differences in vascularity / fit on the wrist vs a finger but who knows how true that is. Maybe it's true only for the existing monitoring tech?

I've seen my average vary from 10-50 and HRV max from 50-140 depending on sickness, exercise routine, hydration, drug use, etc. The quality of that average is interesting to observe as well, ie two nights' average of 40 can look very different depending on the peaks and valleys.

It is challenging though to suss out what effects various things have. It requires a whole lot of normality in my lifestyle so as to limit the number of variables as best I can.