A 44-year-old patient, with narcolepsy-cataplexy, underwent surgery for lumbar disk hernia under spinal anaesthesia. Our purpose was to prevent an interaction between the patient's disease and general anaesthetic agents with the risk of postoperative hypersomnia. During surgical procedure, two narcolepsy fits occurred, without clinical consequences. The postoperative course was uneventful. However, spinal anaesthesia cannot be considered as a technique of choice because of the risk of narcolepsy-cataplexy fits with loss of consciousness and atonia, during regional anaesthesia. General anaesthesia seems to be the best choice for these patients cholinergic agents and mainly the alpha1 adrenergic blocking drugs are contra-indicated as they increase the risk of narcolepsy-cataplexy fits. Anaesthetic sleep, narcolepsy, cataplexy and epilepsy are clinically rather similar. The EEG does not allow to differentiate between narcolepsy and anaesthetic-sleep, whereas cataplexy and epilepsy result in specific EEG patterns.