Semen Ziziphus jujube (SZJ), the seeds of Ziziphus jujuba Mill. var. spinosa, is a kind of traditional Chinese medicine used for its action on insomnia. In order to analyze the effective component, we investigated and compared the sedative and hypnotic effects of three kinds of compounds, flavonoids, saponins, and polysaccharides. Flavonoids, saponins, and polysaccharides were extracted from SZJ and orally administered to mice separately at 17 g kg(-1) per day for certain days before animal tests. Spontaneous motility and coordinated movement tests were used to observe the effects of the three kinds of compounds on the mouse behavior, and sodium barbital-induced sleeping time of mouse were tested to analyze the effects of the three kinds of compounds on the sleep of mouse. Results show that flavonoids and saponins caused a significant reduction of walking time and coordinated movement ability of mouse, significantly prolonged its sleeping time at 40 mg kg(-1), ip, subthreshold dose and increased the sleeping number of animals at 50 mg kg(-1), ip, superthreshold dose induced by coeliac injection of sodium barbital. Polysaccharides did not show any significance in all animal tests. Comparative analysis showed that saponins had a more effective sedative and hypnotic function than that of flavonoids, polysaccharides did not show a sedative and hypnotic effect.