Heart Rate Variability confused me as it is often reported as low in PWME but many people (including myself) observe that their heart rate jumps all over the place and seems highly variable. I think I have got my head round this but not sure if I am on the right track or way off mark. I'll cope below the explanation that I wrote for myself in a word document. Its taken me a while to read up on it and I use hypothetical numbers in my explanation to myself as I can't remember the exact ones or where I read what!!! but just wondered if it theoretically makes sense or not. Thanks Jo I think I got my head round it. Its not about big jumps its about frequent small variations that allow the body to respond to what is happening. they look at the length of the gap between beat 1 and beat 2 and then compare it to the length between beat 2 and beat 3. if the difference between the 2 gaps is above a certain amount (a pretty small amount) it "counts" as a change and they look at the frequency that this occurs from one gap to the next. so in 10 heartbeats the gap length may vary from one to the next say 5 or 6 times (but by a small amount). in low heart rate variability that continual adapting doesn't happen so seems the body is not continually adapting but then may have big jumps. so maybe in 10 heart beats 9 gaps are more or less the same but the 10th has a huge variation. because it is the frequency in which variation takes place, between 2 adjacent gaps, this is lower heart rate variability because it only changed once in 10 beats. so someone could have a heart rate maintaining around say 67-70 bpm but have high heart rate varaibility because there is continual small changes happening to constantly adjust. whereas someone else could have their heart rate jumping about a few times a minute but because most gaps look the same as the one before with occasional big changes this would be classed as low heart rate variability. To me it seems like maybe peoples hearts aren't making the frequent small adjustments needed to adjust as they go along so that they then have to make a big jump or two to compensate and then they stay static at that length of gap for a few beats before they make another jump - rather than the continual small adjustments normally made that allow the overall heart rate to stay fairly stable because there is lots of micromanagement and fine tuning happening on a beat per beat basis.?????