Primary orthostatic hypotension is a rare type of orthostatic hypotension. It is not a disease per se, but a condition caused by several disorders that affect a specific part of the autonomic nervous system, such as multiple system atrophy, young-onset Parkinson's disease, pure autonomic failure, dopamine beta-hydroxylase deficiency, familial dysautonomia, and pure autonomic failure among others. The autonomic nervous system is the part of the nervous system that regulates certain involuntary body functions such as heart rate, blood pressure, sweating, and bowel and bladder control. Orthostatic hypotension is a form of low blood pressure that happens when standing-up from sitting or lying down. Common symptoms may include dizziness, lightheadedness, generalized weakness, leg buckling, nausea, blurry vision, fatigue, and headaches. Additional symptoms can include chest pain (angina), head and neck pain (often affecting neck and shoulders with a coat hanger distribution), decline in cognitive functioning such as difficulty concentrating, temporary loss of consciousness or “blackout”. Some people with primary orthostatic hypotension may also have high blood pressure when lying down. The treatment depends upon several factors including the specific underlying cause including The treatment depends upon several factors including the specific underlying cause and may include physical counter-maneuvers like lying down, sitting down, squatting clenching buttocks, leg crossing, and support garment and medication. [ https://rarediseases.info.nih.gov/diseases/12959/primary-orthostatic-hypotension ]