A rare condition characterized by recurrent hypersomnias associated with hyperphagia, occurring primarily in males in the second to third decade of life. Clinical features include mental confusion, excessive sleep requirements (approximately 18 hours per day), restlessness, and in some cases hallucinations. Episodes have a duration of days to weeks, and may recur several times per year. This condition may resolve spontaneously over several years. (From Adams, et al., Principles of Neurology, 6th ed, p569).