Thirty-something long gray hair may be related to mental stress, nutritional deficiencies, endocrine system disorders and so on. 1. Mental stress: If a person is depressed for a long time, in a poor state of mind or high mental tension, it inhibits the secretion of melanin, which can make the hair turn from black to white. 2. Insufficient nutrition: Hair is an appendage of the skin and needs sufficient nutrition. If the body lacks protein, vegetable oil, vitamin B1, vitamin B2, vitamin B6 for a long period of time, causing the synthesis of melanin cells in the hair follicle to be impaired, it will also lead to the change of hair from black to white. 3. Endocrine system diseases: such as hyper- or hypothyroidism, can cause endocrine disorders, further triggering pigment cell function abnormalities, gray hair. The thirty-something long gray hair can also be seen in other causes, it is recommended that timely medical treatment, follow the doctor’s instructions for relevant examinations, in the doctor’s help to clarify the cause, and targeted treatment or treatment.