I found this information on a series on Netflix called “Human; The World Within”.
Our brain has the synthetic & the parasympathetic memory, these are part of the autonomic nervous system. The synthetic is like the fight-or-flight system. Very quick response.
A build up of even constant synthetic response causes stress within the muscles.
Then it’s when your parasympathetic nervous system takes hold, kind of like a last-resort.
The parasympathetic nervous system helps you do the things that the brain does that we just don’t think of.
A good example which I’ve used before is blinking or even breathing (I haven’t used that before though).