when sitting what causes dizziness
Dizziness, lightheadedness, and the feeling of passing out is a common complaint in people who have low blood pressure. When the blood pressure is too low, not enough oxygen-rich blood is being delivered to the brain, and its function can be affected. If the brain's blood supply is decreased too much, the person may pass out (syncope). Symptoms may worsen when changing position from lying down or sitting, to standing up. In addition to feeling dizzy, associated symptoms may include: 1  Sweating. 2  Weakness. 3  Nausea and vomiting. 4  Shortness of breath. 5  Chest pain.