AbstractThe patient was a 69‐year old male, with apnoea‐tonic convulsion in sleep as the chief complaint. Over the period of 17 years prior to his admission to our clinic he had been treated as a case of night epilepsy, without improvement but aggravation. Satisfactory results of our treatment are briefly summarized as follows.1) Anticonvulsants including diphenyl‐hydantoin proved ineffective, and phenobar‐bital aggravated seizures markedly.2) Methyl phenidate and imipramine or monochlorimipramine proved to be effective, and the last drug was completely suppressed the sleep apnoea. During 15 months after discharge the continuous use of this drug has effectively inhibited the seizures up to date.3) EEG of our case shows abnormal sleep pattern which has no deep sleep pattern. And no remarkable EEG changes were observed before and after administration of monochlorimipramine, but body movements during sleep were more frequent after the administration.4) By recording EEG at the onset of this seizure there was recognized flat EEG suggesting that the tonic convulsion occurring after apnoea is an anoxic convulsion.5) As for the action mechanism of monochlorimipramine, on the basis of our findings that this sleep apnoea is closely associated with a certain depth of sleep, which resembles sleep paralysis of narcolepsy, and it has been concluded that the action mechanism of imipramine and monochlorimipramine is directed to the disturbance of sleep regulating mechanism.6) It is assumed that the mechanism of the present case consists of visceral crisis of tabes dorsalis, resultant hypoexcitability of the brain stem reticular activating system and disturbance of sleep r