The EO was effective over a wide dose range. Its sedative effects reflected in the sleep induction studies were achieved at doses that are 100-fold higher than those found effective in the LDB. In the experimental procedure involving ether- induced sleeping time, only at 1500 mg/kg did the EO decrease the latency to sleep and increase the sleeping time, which proved to be a specific central nervous system effect. According to Tsuji et al. (1996), this effect is not related to a pharmacokinetic interaction with hepatic enzymes, a recognized limitation of barbiturate-induced sleeping time. The decrease in spontaneous motor activity (after long-term treatment) and potentiation of ether-induced sleeping time (after acute treatment at higher doses) strongly suggest central depressant activity of the EO