To investigate the effects of Hewei Anshen Formula(HWAS) on the levels of 5-hydroxytryptamine(5-HT)，dopamine(DA)，and norepinephrine(NE) in the hypothalamus of insomnia model rats.Methods:Sixty male Wistar rats were randomly divided into six groups：a normal control group，an insomnia model group，a diazepam group，and low-，medium-，and high-dose HWAS groups.Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of 5-HT，DA，and NE in the hypothalamic tissues of the rats in each group.Results:The 5-HT level in the hypothalamus of rats in the insomnia model group was significantly decreased(P<0.05)，while the levels of DA and NE were significantly increased(P<0.05) as compared with those in the normal control group.There were no significant differences in 5-HT，DA，and NE levels in the diazepam group and the low-dose HWAS group when compared with the insomnia model group(P>0.05).The medium-dose and high-dose HWAS groups showed significantly higher 5-HT levels than the insomnia model group(P<0.05)，while the levels of DA and NE were significantly decreased(P<0.05).Conclusion:The therapeutic mechanism of the HWAS for treating insomnia may be related to the regulation of 5-HT，DA，and NE levels in the brain.