The autonomic nervous system (ANS) is the part of the nervous system that is responsible for automatic, unconscious, involuntary activities of all the organs of the body. The ANS is regulated by a complex network in the brain called the central autonomic network.

Autonomic medicine concerns disorders of regulation of body processes in which altered activities of one or more components of the ANS adversely affect health. These disorders fall under the broad heading of dysautonomias.

Common symptoms of dysautonomias include inability to tolerate standing (orthostatic intolerance), exercise, or heat; increased or decreased sweating; gastrointestinal disturbances; genitourinary abnormalities; cognitive dysfunction; and fatigue. Dysautonomias may or may not have symptoms.