Human Hair Growth Cycle
The hair grows in a cyclic manner. A relatively long period of growth (that varies with the type and location of the hair) is followed by a short period of rest after which the hair is released from the follicle, and a new growth cycle begins forming a new hair
Thus the length of the growth cycle determines the length of the hair. Hair grows about 3 mm per day (about three tenths the thickness of a dime). Within a year, our scalp and beard on men can produce nearly five inches (13 cm). By comparison, the longest hairs on our arms have a growth cycle of less than two months.
The follicle is also highly mitotic (cell division) and most capable of regeneration. Indeed, we were "designed" so that if hairs were torn out, they would quickly grow back. That is why all active elements of the follicle must be dismantled to cause permanent hair removal
Everyone's hair grows differently, depending on age, weight, metabolism, hormones, ethnicity, medications, pregnancy, and other factors. But all hair goes through three distinct growth phases.
The Growth of Human Hair - Three phases
Hair shedding Cycle
Hair grows from tube-like depressions in the skin called hair follicles. The hair shaft is formed from living cells deep in the follicle. These fragile living cells subsequently die to form the remarkably strong fiber we call a hair. The same follicle is capable of producing more than one type of hair during the course of our lives.
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Anagen phase - The growing phase
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Catagen phase - The transitional phase
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| Telogen phase - The resting phase Lasts 5 - 6 weeks, at the end of which the hair falls out and a new hair begins to form. Approximately 10-13% of our body hair is in this phase at any one time. When growth begins again in the hair follicle, the resting hair is released from the follicle and a new hair is produced. These hairs fall out daily through combing, brushing and simple friction. The time from the anagen to the telogen stages varies depending on the area of the body and the genetic patterns of the person. |
As discussed above, hairs grow in three stages: anagen, catagen and telogen. First, hair cells grow and divide in the anagen phase. Head hair naturally remains in the anagen phase for an extended period of time, up to several years. Hair on your arms, however, will move on to the catagen phase in a matter of weeks. This is when the hair stops growing and transitions to the dormant telogen phase. The hair stops lengthening and eventually falls out naturally through shedding or external trauma such as pulling.
