What term is used for the sensation of lightheadedness when sitting up?

The sensation of lightheadedness when sitting up is referred to as orthostatic hypotension. This condition occurs when there is a sudden drop in blood pressure upon standing up or sitting up from a lying position. It happens because the body is not able to quickly adjust the blood pressure to accommodate the change in position, resulting in insufficient blood flow to the brain momentarily. This often leads to feelings of dizziness or lightheadedness, which is characteristic of orthostatic hypotension.

In contrast, dizziness is a more general term that encompasses various forms of unsteadiness and does not specifically refer to the positional change and subsequent drop in blood pressure. Nausea typically refers to an uncomfortable sensation in the stomach often associated with the urge to vomit, which does not directly relate to the lightheadedness triggered by bodily movements. Vertigo involves a specific spinning sensation, usually experienced when there’s an issue with the inner ear or brain, and is distinct from the feeling of lightheadedness related to changes in posture.