Children crying in the middle of the night at two or three o’clock is mostly due to hunger, calcium deficiency, environmental factors, colic and so on. 1. Hunger: If children do not eat enough before bedtime, they will wake up and cry in the middle of the night because of hunger. 2. Calcium deficiency: with the growth and development of children, it is easy to have calcium deficiency, once calcium deficiency, it will lead to the cerebral cortex is too excited, easy to wake up and cry at night. 3. Environmental factors: may be due to environmental noise, such as in the evening there will often be some relatively loud noise, easy to wake up the child. 4. Colic: In the middle of the night when the temperature is relatively low, once the child’s abdomen is cold, it is easy to trigger colic. Children crying in the middle of the night at two or three o’clock may also be due to other causes, if the symptoms continue to be unrelieved, should be timely to the hospital to identify the cause or targeted treatment or treatment.