The 35-year-old sideburns hair gray may be caused by age, mental stress and hereditary factors. 1. Age: With age, metabolism slows down, the number of melanocytes in the hair follicle will reduce the decline, can not synthesize enough melanin, sideburns will appear white hair, is a normal physiological phenomenon. 2. Mental stress: If you are in a state of long-term mental tension, emotional anxiety, irritability, and decreased sleep quality, it will affect the normal synthesis of melanin by the melanocytes in the hair follicles, resulting in gray hair on the temples. 3. Heredity: family hereditary phenomenon, if there is a hereditary gray hair patient in the family, the chances of the offspring appearing gray hair will increase, which may lead to 35-year-old hair on the temples become white. If the hair on the temples turns gray at the age of 35, and accompanied by other symptoms, it is recommended to go to the hospital in time, to clarify the cause of the disease, under the guidance of the doctor for treatment.