History -- History and Overview of Orexin/Hypocretin Research -- Overview of the Orexin/Hypocretin Neuronal System -- Orexin and Orexin Receptors -- Orexin Projections and Localization of Orexin Receptors -- Neuronal Responses to Hypocretin/Orexin -- Afferent System of Orexin Neurons -- Assessment of Orexin/Hypocretin Functions in Tissue and Biological Fluids -- Hypocretin Measurements in the C…