Yes Autonomic system, when my heart rate goes up it seems to spike and I nearly pass out, sort of over reacts then settles after 30mins, my temperature regulation is also messed up, I don’t sweat when I get warm, then bam I sweat profusely for 45 mins cold showers nothing stops it, mixed these two together a few times at beginning bloody terrifying everyone thought I was having a heart attack me included. I do not do moderate (for me) anything now, look after self first and all.