A two-year-old baby always cries in the middle of the night, which may be caused by physiological reasons, or due to indigestion, rickets and other pathological reasons. 1. Physiological reasons: If the temperature of the environment in which the toddler sleeps is too high or too low, as well as mosquito bites, noisy surroundings, etc., may affect the quality of sleep, and the phenomenon of toddlers crying in the middle of the night occurs. These are physiological phenomena, generally do not need special treatment. 2. Pathological causes: (1) indigestion: because the digestive function of two-year-old children is not yet well developed, when the diet is too much, too much greasy intake, can cause indigestion. Toddlers can occur abdominal distension, abdominal pain and other uncomfortable symptoms, which can appear in the middle of the night crying phenomenon. (2) Rickets: It is a kind of chronic disease mainly characterized by bone lesions caused by abnormal calcium and phosphorus metabolism and ossification disorder due to various factors. It may be caused by insufficient skin synthesis of vitamin D, rapid growth and development, etc. Young children in the early stages can appear excessive sweating, occipital baldness, irritability, night terrors and other symptoms, but also the phenomenon of crying in the middle of the night. Two-year-old baby always crying in the middle of the night, if you exclude physiological factors, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease and then follow the doctor’s instructions for treatment, to avoid delaying the condition.