Nine-month-old babies sleep a lot of sweat on the head may be caused by environmental factors, metabolic factors lead to normal phenomena, but may also be abnormal phenomena, including vitamin D deficiency, disease factors. 1. Normal situation: the baby sleeps when the environment is hot and stuffy will also lead to a lot of sweat on the head, at the same time, the baby’s vitality, every day in the growth of the metabolism to be faster than the adults, the metabolism accelerated, will stimulate the function of the sweat glands, which will lead to the discharge of more sweat. 2. abnormal situation: lack of vitamin D and calcium of the baby will appear excessive sweating, night terrors, restless sleep at night, occipital baldness and other symptoms, only timely supplementation of vitamin D and calcium, sweating will be improved. At the same time, we should pay attention to the disease caused by fever will also have excessive sweating, need to pay attention to. It is recommended that the nine-month-old baby sleeps with a lot of sweat on his head can go to the hospital in time to do the appropriate examination, to avoid delaying the condition.