<prompt> Which of the following is the most impoant pa of brain involved in NarcolepsyNeocoexHypothalamusHippocampusPons  <response>: Answer is B Hypothalamus: Narcolepsy in humans is caused by deficiency of hypocretin Orexin a neurotransmitter produced in the Hypothalamus. Recently several convergent lines of evidence suggest that the hypothalamic neuropeptide hypocretin orexin is involved in the pathogenesis of Narcolepsy- Harrisons 181h220 Narcolepsy Narcolepsy is a common sleep disorder charachterized by excessive daytime sleepiness, cataplexy episodes of muscle weakness triggered by emotions, hypnagogic hallucinations and sleep paralysis. Narcolepsy classic Tetrad Excessive day Time somnolence Sudden weakness or loss of muscle tone without loss of consciousness often elicited by emotion cataptexy Hallucination at sleep onset Hypnagogic Hallucination or upon awakening Hypnopompic Hallucination Muscle Paralysis upon awakening Pathology Pathogenesis Most impoant cause of narcolepsy is believed to be deficiency of neuropeptide Hypocretin orexin produced in Hypothalamus Autoimmune All narcoleptics with cataplexy are positive for HLA DQBI 0602 