Nausea and vomiting in the middle of the night can be caused by chronic gastritis, functional dyspepsia, peptic ulcer and other factors. 1. Chronic gastritis: the disease is caused by a variety of factors of gastric mucosal inflammatory lesions, patients often have no obvious symptoms, but some patients may have epigastric discomfort, lack of appetite, nausea, vomiting and so on. 2. Functional dyspepsia: This disease is a type of functional gastrointestinal disease, patients may manifest epigastric fullness, nausea, vomiting and other symptoms. Some patients may also suffer from anxiety, irritability and other mental symptoms. 3. Peptic ulcer: the disease is related to Helicobacter pylori infection, excessive secretion of gastric acid, etc. Common symptoms include epigastric pain, nausea, vomiting, loss of appetite, belching and so on. There are many other reasons for stomach discomfort and nausea, if the patient has stomach pain accompanied by nausea, vomiting and other discomforts, it is recommended to consult a doctor in a timely manner, to be clear after the cause of timely treatment, it is not recommended to take their own medication, so as not to cause adverse reactions.