"The clinical hallmark of manic-depressive illness is its recurrent, episodic nature. Byron had this in an almost textbook manner, showing frequent and pronounced fluctuations in mood, energy, sleep patterns, sexual behavior, alcohol and other drug use, and weight (Byron also exhibited extremes in dieting, obsession with his weight, eccentric eating patterns, and excessive use of epsom salts). Although these changes in mood and behavior were dramatic and disruptive when they occurred, it is important to note that Byron was clinically normal most of the time; this, too, is highly characteristic of manic-depressive illness. An inordinate amount of confusion about whether someone does or does not have manic-depressive illness stems from the popular misconception that irrationality of mood and reason are stable rather than fluctuating features of the disease. Some assume that because an individual such as Byron was sane and in impressive control of his reason most of the time, that he could not have been "mad" or have suffered from a major mental illness. Lucidity and normal functioning are, however, perfectly consistent with-indeed, characteristic of-the phasic nature of manic-depressive illness. This is in contrast to schizophrenia, which is usually a chronic and relatively unrelenting illness characterized by, among other things, an inability to reason clearly."