Nine-month-old baby sleep head sweat can be seen in physiological phenomena, pathological conditions (such as vitamin D deficiency, febrile illness), specific need to analyze and judge according to the baby’s situation. 1. Physiological phenomenon: if the baby sleeps around the environment temperature is high, or the blanket is thicker, can make the baby appear the above phenomenon, adjust the room temperature and reduce the blanket, head sweating phenomenon can be relieved. 2. Condition: (1) Vitamin D deficiency: such as nutritional vitamin D deficiency rickets, in the early stage of the disease, there may be increased sweating and other phenomena of increased neural excitability, accompanied by irritability, crying and other phenomena, which may be accompanied by cranial softening and other skeletal changes. (2) Febrile diseases: such as infantile acute rash, fever may appear at night, and the phenomenon of increased sweating may appear, often in fever for 3~5 days, after the appearance of rash, body temperature is normal, and the phenomenon of night sweating is relieved. (3) Tuberculosis: there is a history of exposure to tuberculosis, and night sweats, accompanied by fever, with variable fever, cough, and mental depression may occur. It is recommended to consult a specialist for evaluation and judgment if necessary.