I'd say that much of my fatigue is caused by hypo perfusion of blood to brain. Any sustained low blood pressure situation reduces glucose and oxygen to my noggin.
Noggin goes on strike and demands I lay down until it feels refreshed.
At its worst (I'm sure you can relate ) I can't speak, I just get home lie down and 'pass out ' into an instant sleep that is not disturbed by noise.
I count myself lucky that it is not full POTS . I have always been able to get somewhere to lie down.
In a healthy population, exercise is documented to lower resting blood pressure. During exercise BP goes up, but the cumulative after effects are a lower BP.
So when I feel okay and go for a walk , the after effect is lower blood pressure even when sitting. Hence one of the reasons cognition suffers or feels very demanding and more tiring.
When I stand up my blood pressure is low but also pulse pressure goes very small (difference between systolic and diastolic ). For instance 74/63 ! Pulse pressure is 11. I believe it's better to have a pulse pressure of 30.
For me the low blood pressure is a (the?) major disabler.
Re adrenaline. When Bp low and I'm on my feet , my heart rate increases (140 highest I've seen it standing motionless ). I am guessing the body has squirted adrenaline to compensate for the low blood pressure ..to keep the brain alive. Cue feelings of anxiety, breathlessness and more burnout.
When the docs told me there was nothing wrong with me, I pushed on with my active lifestyle when I could. As I got sicker I was even working at a standing desk! No wonder I was trashed!
When I overdo it (walk stand ) BP disables , fatigue kicks in, glands up , sore throat, bed.
My o2 glucose starved noggin makes my body lie down so it can refresh
That's the way I see it
Its worse mendturally so I'm also looking at that relationship but haven't solved it yet
I'm taking gotu kola as an experiment as its good for venous blood return (apparently ).
When I'm out of gotu kola if it hasn't been amazing then I'll try glychirrized licorice.
It has similar effects to fludrocortisone on sodium. But you must use GLYCHIRRIZED!
Most licorice supplements are de glychirrized because it raises BP otherwise and that's dangerous in your average population.