Stomach acid reflux at night is usually caused by improper eating habits, reflux esophagitis, duodenal ulcer and other factors. Many people have improper eating habits, such as preferring spicy, greasy, sweet and acidic foods, especially in the evening when they consume a lot of these foods. Since these foods are difficult to digest and stimulate excessive secretion of stomach acid, the symptoms of acid reflux often occur at night. In reflux esophagitis, the protective barrier of the esophageal mucosa is damaged, and at night is the period of highest secretion of gastric acid, once the pillow is too low or the cardia sphincter is relaxed during sleep at night, it will lead to acid reflux into the esophagus and invade the esophageal mucosa, resulting in symptoms such as burning, pain and acid reflux in the stomach. Some people not only have acid reflux at night, but also have severe pain in the stomach, which is related to duodenal ulcer, caused by the high concentration of stomach acid that irritates the duodenal mucosa.