Some can stand and do things, some are bedridden. If the blood does not stay in the brain there is no standing or sitting. No choice there. Many faint 20 times a day.

Each case is different. Glad that man can do things. Those activities are impossible for most people.

The Autonomic nervous system is in charge of digestion, excretion, breathing, temp. regulation, blood flow, heart rate, on and on. All vitals and organs are affected.

The Autonomic Nervous System is supposed to keep our bodies in homeostasis. It can be very serious for most people. Every illness you have on top of it brings a relapse. Some find a cause like Lyme etc and they can improve.