The purpose of this experiment is to study the effect of Rehmanniae Radix water extract on sleep in rats and explore its possible mechanism.The effect of Rehmanniae Radix water extract was evaluated by referring to the Functional Test and Evaluation Methods of Health Food (2022 Edition) for sleep improvement tests.Furthermore,the insomnia rat model was established,and the central neurotransmitters in the hypothalamus and their corresponding receptors mRNA expression levels were detected,as well as the content of inflammatory factors in the serum of the rats.The results showed that the Rehmanniae Radix water extract could improve the sleep of rats,and the safety was good.Furthermore,it significantly increased the contents of gamma-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) and decreased the contents of glutamic acid (Glu) and dopamine (DA) in the hypothalamus of insomniac rats,and the expression of receptor mRNA of the corresponding neurotransmitters was affected similarly.In addition,the contents of TNF-α and IL-1β in serum decreased significantly and IL-10 increased significantly.These data indicated that the Rehmanniae Radix water extract could improve sleep in rats by regulating neurotransmitters and cellular inflammatory factors.