A normal scalp contains an average of 90,000 to 65,438+0,400 mature hairs, more fluff and imperceptible hairs. Hair growth and replacement are periodic. The growth cycle of normal hair can be divided into three stages: growth period, regression period and rest period. In the growing period, hair begins to grow from the base of hair follicle, and can continue to grow for 2 ~ 4 years until it is fully grown. Then there is the regression period, which lasts for 2 ~ 4 weeks, during which the hair stops growing actively. The last rest period lasted about 3 months, and then the hair began to fall off. Then new hair begins to grow again, repeating another growth cycle. Everyone's hair is often at different stages of the growth cycle, and shedding and growth are in a dynamic balance. On average, about 65,438+000 hairs fall off every day, but at the same time, the same number of hairs normally enter the growth period.