Most of us spend at least two-thirds of our lives either sitting or standing. It is somewhat surprising, therefore, to find not a single book devoted to disorders caused by derangements of the normal physiological adjustments to changes in posture. In fact, until very recently, medical students have not even been advised to measure the blood pressure and heart rate in the upright posture as part of the routine physical examination. Although Bradbury and Eggleston first described orthostatic hypotension as a consequence of autonomic insufficiency in 1925, interest in orthostatic disorders has...