Dan Neuffer has an interesting take on ANS dysregulation in ME, just read his book “CFS Unravelled”. His theory is that CFS has its cause in chronic arousal of sympathetic mode of the ANS. This causes high output of cortisol and other stress hormones. Which will eventually lead to damage in tissue, organs, glands - and dysregulation in adrenals, blood pressure (POTS), impaired digestion, impaired detox, lowered immune system, pain sensitation, blood sugar issues aso. Eventually being chronically stressed can make the body “shut down”, maybe to avoid the further damaging effect from long term cortisol etc, and metabolism will be substantially downregulated.
He healed himself through a process he calls ANS Normalisation - the idea is to use techniques to gradually reduce chronic SNS (sympathic nervous system) arousal - a big part of this is identifying stressors (of which being sick ME is a major one, a constant source of anxiety and worry). He recommends yoga, meditation - and to be less occupied with looking for symptoms and possible solutions (a hard one!) because subconcious circuitry (amygdala?) will interpret this as a threat, and it will only activate SNS.
Most interesting, since I came to believe since this summer that dysautonomia is a big part of ME.
PS! I am sure this must have been discussed earlier here on the forum..Sorry for not taking the effort of looking that up. Posting this from my phone.