As I have typed before, just got a new HRV device. I have just done 5 minutes aside on my neck and my HRV slightly changed. I normally do small circles in the correct place, but surprised that it didn't change as much like my 3 minute cold shower. is this what we would expect or not?

I received my HRV device yesterday and it says that a high HRV is good and a lower one may be an indication of something wrong. When we stimulate our vagus nerve its to make the HRV lower, so how do we judge what a good HRV number is? and also does age affect the HRV? is there some sort of chart to refer to, if it does? I'm 55 and it seems like my high and low scores are 48 to 30.

my HRV device arrived yesterday and I have been wearing it for about 24 hrs. I had a cold shower and my HRV went from 48 to 30 and then some time after I did the Norwegian 4x4 interval training and my HRV went down about the same amount. I have been sitting down and relaxing for about over an hour and my HRV is about 30 again. In each case has my body responded in the correct manner?

I have a vibration plate that vibrates at 40Hz, it vibrates the whole body, do you think this would have the same effect on memory as ultrasound at 40hz?

there are lots of different shapes and sizes of pillows out there, is there a pillow that helps more than others in sleep and maybe help or stimulate the VN