Hair loss on the top of a man’s head is considered to be androgenetic alopecia, and the causes are mainly genetic factors, excessive secretion of androgens, bad habits, and mental factors. 1. Hereditary factors: androgenetic alopecia has a clear genetic predisposition, androgenetic alopecia patients in the previous generation, the incidence of the next generation is higher. 2. Excessive secretion of androgen: excessive secretion of hormones may lead to small scalp follicles, thinning of hair and shortening of growth cycle, resulting in hair loss. 3. Bad habits: regular smoking, alcoholism, staying up late, poor sleep quality, malnutrition, immune function disorders, easy to aggravate androgenetic alopecia. 4. Mental factors: mental tension, long-term anxiety, depression in terms of mood can also lead to androgenetic alopecia. Androgenetic alopecia, there may be other reasons, you need to go to the hospital for examination, clear cause and follow the doctor’s instructions for treatment.