The purpose of this study was to determine the arousal effect of physostigmine after lormetazepam sedation on the human EEG. 12 male volunteers received 2 mg/kg bm lormetazepam and 30 minutes later physostigmine 2 mg preceded by atropine 1 mg. Generally an arousal effect of physostigmine could be clinically observed and more objectively demonstrated by reduced sleep stages in the vigilosomnogram (p less than 0.05). 2 volunteers did not fall asleep. 9 volunteers were awake 5-12 minutes after termination of physostigmine injection. 1 volunteer did not show any effect. Resedation and parasympathetic side effects did not occur. In earlier studies deep sleep stages after lormetazepam 1 or 2 mg/70 kg bm lasted 70 to 120 minutes. Physostigmine is recommended to counteract undesirable benzodiazepine induced sedation.