The condition that causes patients to sleep with stomach pain at night but not during the day is first considered to be due to chronic enteritis. Because patients with chronic enteritis may not feel abdominal pain during the day when their attention is diverted. However, at night when the patient’s attention is shifted to the abdomen in the dead of night, the pain may be felt. It may also be caused by parasites in the intestine, because parasites in the intestine are less active during the daytime and may increase their activity only at night, resulting in the symptoms of stomach pain. It can be treated with appropriate medication, such as intestinal wormer or anthelmintic. If the parasites are removed from the intestine, the pain will be relieved significantly.