ABSTRACT
Although obesity has been recognized as a frequent feature in human narcolepsy already in the 1930s (1), metabolic abnormalities and their causes have rarely been studied until very recently. Early studies on an increased incidence of type II diabetes (2,28), or reduced food intake in narcoleptic subjects (3), did not trigger any major scientific interest until 1998, when the disorder was discovered to be associated with an acquired deficiency of the production of orexins (also called hypocretins). These two peptides, derived from a common precursor protein expressed almost exclusively in the lateral hypothalamus, are tightly involved in both, the regulation of sleep and wakefulness (4), and the regulation of appetite and metabolism (5). Hence, it is very likely that orexin deficiency plays a pivotal pathophysiological role in both, the sleep wake disturbances and abnormalities in endocrine and metabolic systems found in narcolepsy. The focus of the present chapter is alterations of body weight, appetite and metabolism in narcoleptic patients, whereas another chapter in this book concentrates on endocrine abnormalities (6).
