Stomach pain lying down may be due to gastritis, peptic ulcer, gastroptosis and other diseases and symptoms. 1. Gastritis: patients usually appear mucous membrane damage, increased secretion of gastric acid phenomenon, increased secretion of gastric acid can lead to further aggravation of the state of gastric mucous membrane damage, the phenomenon of stomach ache can occur, and lie down mainly due to the change of position, through the change of position, to reduce the stimulation of gastric acid on the mucous membrane injury site, in addition to lying down after the muscle relaxation, the symptom of stomach ache will be relieved. 2. Peptic ulcer: patients usually appear congestion and edema phenomenon, and such patients and gastritis symptoms, there can be an increase in gastric acid secretion phenomenon, which will stimulate the damaged ulcer surface, resulting in further aggravation of the symptoms of gastric pain, lying down can be a change of position, change the position of the gastric acid may flow to other parts of the ulcer surface, and thus do not stimulate, and therefore the pain will be relieved. 3. Gastroptosis: nausea and vomiting, abdominal pain, abdominal distension and other symptoms can occur, but also stomach pain can be relieved by lying down, can be improved through functional exercises, less food and more meals. There may also be other reasons for the above conditions, and patients are advised to consult a doctor in time.