Sudden diarrhea in the morning is considered to be caused by non-disease factors, such as a cold abdomen, but it may also be caused by disease factors, such as acute gastroenteritis, irritable bowel syndrome and so on. 1. Non-disease factors: If the abdomen is cold during sleep or if too many cold drinks are ingested before bedtime, they can stimulate gastrointestinal motility, thus triggering diarrhea. 2. Disease factors: (1) Acute gastroenteritis: mostly due to bacterial or viral infections, in addition, eating cold, unclean food or overeating can trigger acute gastroenteritis, resulting in sudden diarrhea, abdominal pain, nausea in the morning, and will be accompanied by fever, headache and other symptoms. (2) Irritable Bowel Syndrome (IBS): It can also cause sudden diarrhea in the morning, accompanied by abdominal pain, which can be triggered or aggravated when the patient is under stress or emotional excitement, but the symptoms can be relieved after the abdominal pain is relieved after meals. In addition, there are many other causes can cause sudden diarrhea in the morning, it is recommended to sleep well covered bedding, stop intake of cold drinks, self-monitoring for a period of time, if the phenomenon still occurs, should be timely to the hospital.