I sometimes get dizzy when I stand up. What causes this?I sometimes get dizzy when I stand up. What causes this?

This problem is called orthostatic dizziness and is often caused by a drop in blood pressure upon standing (orthostatic hypotension). Orthostatic hypotension can be caused by a number of conditions, including diabetes, Parkinson's disease, heart failure, drop in blood volume, dehydration, infection, and a number of medications (such as diuretics and blood pressure medicines). A less common cause of orthostatic dizziness not associated with falling blood pressure is caused by abnormalities in the inner-ear vestibular (balance) system, or its connection to the brain.