The causes of children’s crying at night include being frightened, gastrointestinal dysfunction, poor surroundings, hunger, vitamin D deficiency and so on. 1. Fright: If children are frightened during the day, watch TV with stimulating images, or have nightmares, they may cry at night, so you can comfort your child appropriately, and tell them some nice stories before going to bed. 2. Gastrointestinal dysfunction: for example, the abdomen is cold, overeating, eating cold food, etc., resulting in gastrointestinal dysfunction, the symptoms worsened at night, abdominal distension, abdominal pain, diarrhea and so on. 3. Poor surrounding environment: If the surrounding environment is noisy, high indoor temperature or too much bedding, the child is uncomfortable during sleep and may cry at night. 4. Hunger: infants and young children also have to consider hunger, the emergence of nighttime crying, such as insufficient amount of breast milk. 5. Vitamin D deficiency: children usually vitamin D intake is insufficient, the lack of calcium and phosphorus metabolism disorders caused by the lack of nerve excitability increases, easy to worry, easily provoked, induced by night crying. Children often cry at night, try to take the child to the hospital to find out the cause of the disease and then treatment.