Children crying at night, may be related to physiological factors, may also be due to indigestion, vitamin D deficiency rickets, colic and other causes. 1. Physiological factors: for example, children at night in the sleep environment is too noisy, the environment temperature is too high, too low, or during the day by excessive shock, etc., may lead to crying at night. 2. indigestion: children in the daytime if overeating, or eating cold, indigestible food, may lead to indigestion, causing abdominal distension discomfort, which may cause night crying. 3. Vitamin D deficiency rickets: common in younger infants, due to severe vitamin D deficiency, rickets induced, resulting in increased neural excitability, which may cause severe crying at night, can also be accompanied by difficulty in sleeping, excessive sweating and other manifestations. 4. Colic: common in small infants, usually caused by lactose intolerance, milk protein allergy or overfeeding and other factors. When colic occurs at night, it may cause severe crying due to abdominal pain, and may also be accompanied by perioral pallor, flushing and other manifestations. Children crying at night, there may also be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.