Waking up in the middle of the night with an open stomach and a bitter mouth is mostly seen in gastroesophageal reflux, oral diseases, liver and gallbladder diseases. 1. Gastroesophageal reflux: mostly accompanied by chronic gastritis, gastric ulcer, etc., the patient will have different degrees of gastric dynamics decline, the food stays in the stomach for a long time, the emptying slows down, which will lead to reflux to the esophagus and the oral cavity caused by the phenomenon of bitter mouth. 2. Oral diseases: gingivitis, periodontitis, etc., there are often anaerobic infections, due to tissue destruction, may lead to dry mouth and bitter mouth. 3. Liver and gallbladder diseases: such as cholecystitis, gallstones, fatty liver, etc., often also affect the digestive function, resulting in waking up in the middle of the night with a bitter mouth. Wake up in the middle of the night stomach open mouth bitter, there may be other causes, it is recommended to consult a doctor in a timely manner, under the guidance of a doctor to clarify the cause and targeted treatment, do not take medication on their own, so as not to delay the condition.