Baby sleep hair sweat a lot of physiological reasons, such as body temperature center development is not perfect, clothing is too thick, etc.; there are pathological reasons, such as cardiopulmonary diseases. 1. Physiological reasons: the baby’s thermoregulatory center is not fully developed, can not be like adults, can only increase the amount of sweat to maintain the core body temperature. When the clothing is too thick or the room temperature is too high, it will also increase the amount of sweating to lower the body temperature. Since the active sweat glands of babies are concentrated in the head, they will sweat a lot when they sleep. 2. Pathological causes: some cardiopulmonary diseases, such as congenital heart disease, due to the reduction of cardiac output and sympathetic excitation will cause sweating during sleep, accompanied by cyanosis, asthma and other manifestations. In addition, tuberculosis can cause more sweating during lunch break. Baby sleep hair sweat a lot may also have other pathological reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.