Autonomic dysfunction involves the autonomic nervous system (ANS) being out of balance. The autonomic nervous system is responsible for automatic bodily functions such as blood pressure regulation, sweating, heart rate, body temperature, breathing rate and functions of organs including the liver.
One branch of the ANS is responsible for gearing the body up for fight-or-flight in stressful situations (sympathetic nervous system, or SNS), or when a physical demand increases, and the other branch is responsible for returning the body systems to baseline and physical maintenance (parasympathetic nervous system, or PNS). When an organism needs a sudden increase in physical effort (as in the case of a threat), the SNS activates an increase in blood pressure, heart rate, breathing rate, sweating – all functions which assist in supplying what is needed for sudden large-muscle movement. After the threat has passed, the PNS takes over by bringing the systems back to resting state and completing the routine maintenance needed to keep everything healthy.
The process of activating and deactivating bodily systems under normal circumstances is a delicate balance. When that balance is not functioning, most commonly, blood pressure and heart rate are noticeably affected. This shows up as orthostatic hypotension – when going from sitting to standing, blood pressure does not increase as needed to supply more blood to the brain. This creates lightheadedness. An unregulated heart rate also often occurs – difficulty increasing when needed, and/or decreasing when resting. Other symptoms include difficulty with digestion, sweating that is either lacking or excessive. The dysfunction is generally caused by an underlying health condition affecting the nerves that communicate with those functions.