Vomiting water in the middle of the night is caused by improper diet, reflux esophagitis, duodenal ulcer and other factors. It is best not to consume any food for 2 hours before going to bed, especially to avoid overly acidic food, otherwise it will not only lead to indigestion, but the stomach glands will also secrete a lot of stomach acid when they are stimulated, and it will even lead to acid vomiting in the middle of the night. In some people with reflux esophagitis, not only does the stomach secrete too much acid, but the protective barrier of the esophageal mucosa is also damaged. In most cases of reflux esophagitis, the cardia sphincter is relaxed, and at night, when the stomach acid secretion is at its peak, it is easier for the stomach acid to reflux through the cardia sphincter to the throat, causing irritation to the throat and causing vomiting in the middle of the night. In the middle of the night, there is no food in the stomach, so the stomach acid will enter the duodenum in a high intensity state. Some people who suffer from duodenal ulcer themselves will not only experience severe pain in the stomach, but will also be accompanied by acid vomiting.