Children crying in the middle of the night, clinical possible causes are environmental factors, indigestion, calcium deficiency and so on. 1. Environmental factors: If a child’s sleeping environment is noisy or brightly lit, his or her sleeping condition will be seriously affected, thus causing the child to cry in the middle of the night. 2. Indigestion: children eat more before going to bed, which will increase the digestive burden of the child’s gastrointestinal tract, resulting in indigestion, clinical manifestations of bloating, abdominal pain, nausea, vomiting, etc., which will also make the child unable to sleep and manifested in the middle of the night crying. 3. Calcium deficiency: children in the usual intake of nutrients is not sufficient or unbalanced, may cause its body lack of vitamin D and calcium deficiency, will lead to the child in the night local muscle, nerve excitability increased and appeared in the middle of the night crying. If it is an environmental factor, parents are advised to provide a quiet and comfortable sleeping environment for their children; if it is a disease factor, parents are advised to take their children to a specialized hospital for examination and treatment.