The first clinical observation of excessive salivation may be caused by indigestion. If you eat too greasy or too much food at night, you may have excessive salivation at night when you sleep. Saliva is secreted according to the needs of our body. After eating, saliva is secreted relatively more. Saliva is further secreted when the stomach is not fully digested after eating. Saliva contains amylase, which stimulates further secretion of gastric acid. In Chinese medicine, saliva is mainly caused by spleen deficiency. As the spleen is the root of the posterior, spleen deficiency will also lead to more saliva. It may be regulated with drugs to strengthen the spleen and stomach. For the elderly, in addition to drooling, there are no other conditions such as the absence of teeth, certainly very easy to drool. Older people with crooked mouth and found to have more drooling may have cerebrovascular disease and is something to be aware of.