The average human head has about 100,000 hair follicles; each follicle can grow about 20 individual hairs during a person's lifetime. Statistics show that most men have a 50% chance of experiencing hereditary hair loss by their 50th birthday. The normal cycle of hair growth lasts from two to six years.
Some mycotic infections can cause massive hair loss. One type of baldness is called traction alopecia, which is most commonly found in people with ponytails or cornrows who pull on their hair with excessive force. Fungal infections of the scalp can cause hair loss in children which is easily treated with antifungal medicines.
Hair loss may occur if male or female hormones, known as androgens and estrogens, are out of balance; correcting the hormone imbalance may stop the hair loss. Some drugs or medications can cause hair loss, which improves when you stop taking the medicine; medications that can cause hair loss include blood thinners, medicines used for gout, and chemotherapy drugs used for cancer, too much vitamin A supplementation, birth control pills and antidepressants. Wearing a hat generally shouldn't cause baldness, though it's a good idea to give your scalp a rest and let it breathe for several hours a day.