Acid reflux in the middle of the night is associated with cardia flaccidity, indigestion, duodenal ulcer, and gastroesophageal reflux. The cardia is located between the esophagus and the body of the stomach, and when there is a temporary disorder in the neuromuscular regulation of the cardia area, it can lead to the appearance of cardia relaxation. In the middle of the night, the peak of human gastric acid secretion, when the secretion of gastric acid will be relatively more, many people in bed because the cardia position is relatively high, the esophagus is relatively low, the gastric acid in the stomach easily through the cardia into the esophagus, thus causing gastric acid reflux performance. People with indigestion eat indigestible food at night, because the food can not be emptied in time, will stimulate excessive secretion of gastric acid, will also cause stimulation of the stomach wall, will lead to acid reflux performance in the middle of the night. Some people with acid reflux in the middle of the night is long-term, accompanied by severe pain, should be alert to the duodenal ulcer disease.