[A 15-year-old boy suffering from a severe case of Kleine-Levin syndrome]

Kleine-Levin syndrome (KLS) is a rare disease characterised by recurrent hypersomnia combined with behavioural and cognitive disturbances. We present a case report of a 15-year-old Danish boy with a severe case of KLS, who suffered frequent episodes especially in the beginning of the disease course. The boy presented with somnolence, speech latency, hallucinations and confusion. Routine paraclinical investigations were normal. The symptoms did not respond to medical treatment but resolved spontaneously after 12 days. The case report illustrates the diagnostic challenge of this rare disease.