autonomic dysfunction
When you have autonomic dysfunction (sometimes called dysautonomia), you may have problems with any part of your autonomic nervous system (ANS). This can lead to symptoms like headache, orthostatic intolerance (when your body struggles to adapt to being upright), fatigue (feeling weak and tired), dizziness, heart palpitations (racing or fluttering heartbeat), shortness of breath, poor body temperature control, nausea and other digestive symptoms, urinary problems, and problems with the blood vessels in your hands and feet.
Your ANS controls several basic body functions, such as heart rate, blood pressure, body temperature, breathing rate, digestion, skin sensation, bladder, sweat glands, and metabolism. These body functions are involuntary, which means you usually can’t consciously control them.
Your ANS is made up of 3 parts:
Your sympathetic nervous system controls your body’s “fight or flight” response by raising your heart rate and releasing energy
Your parasympathetic nervous system controls your involuntary body processes during relaxation and other ordinary situations, including slowing down your heart rate and lowering your blood pressure
Your enteric nervous system controls your digestive (gastrointestinal) system