Abstract：Insomnia is a common and frequently occurring disease in clinic. In Huangdi Neijing，the mechanism of sleep is described as "the decline of yang qi and the exuberance of yin qi cause heavy eyes”；the part where wei qi goes from yang to yin is the spleen and stomach；the disorder of qi movement of spleen and stomach and the disability of wei qi entering from yang to yin are the causes of insomnia. According to this theory，based on the Banxia Xiexin tang，this paper applies the method of acrid medicinals open and bitter medicinals promote descent to regulate the spleen and stomach，guide wei qi go from yang to yin，and treat insomnia，which is always effective.