Sudden crying in the middle of the night may be caused by hunger, poor environment and other physiological factors, or by intussusception, rickets and other diseases. 1. Physiological factors: when the child suddenly cries in the middle of the night, it is necessary to consider that it may be caused by hunger, or environmental factors such as high or low temperature, which is a normal physiological phenomenon. 2. Intussusception: the disease is mainly caused by abnormal intestinal peristalsis rhythm, generally children’s intussusception and viral infections, intestinal developmental malformations, polyps and other factors related to the typical symptoms of abdominal pain, blood in the stool, abdominal masses, etc., because of the child’s age, and will not be able to express through the language of discomfort, so they can only cry. 3. Rickets: the causes of this disease include insufficient intake of vitamin D, lack of sun exposure, may also be related to preterm labor, vitamin D deficiency during pregnancy and other factors, the main symptoms are excessive sweating, restless sleep at night, night cries, night terrors, etc., which can be manifested in the middle of the night when the child suddenly cries. Children suddenly cry in the middle of the night, there may also be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.