Hair grows in cycles. Part of the hair in your head is growing, part is undergoing involution and part is just resting. Just what are these processes and how do they relate to hair loss?

When we are born we already have all follicles we will ever have during the course of our life. On each follicle the root of a hair will be formed and that hair will grow. Some follicles begin growing first, some later, and if you would analyze your scalp right now some of the hairs would be growing, some resting and some receding.

This cyclic process begins with the growth of a new hair. Inside a follicle cells will use nutrients and create the structure from which a new hair will emerge. As cells create that structure the hair grows from the scalp, emerging and further continuing its growth. This phase of the process, the growth phase, is called “anagen”.

Anagen is a process that lasts from two to three years and is followed not by resting but by involution.

Involution means that the hair will become smaller and thinner, as if it was growing back down. This involution phase is called catagen, which lasts only two to three months, compared to the two to three years of anagen.

But hair does not fall in catagen. Instead, it enters a rest phase, during which it does not grow or recedes. This phase is the telogen and it lasts three to four months.

When telogen is over, hair is released from the shaft and shed. Then, at the same follicle, a new hair begins growing, entering anagen.

Because follicles started growing hair at different phases and the phases themselves have different durations for each follicle, the cycles for each follicle are not happening at the same time, or you would lose all your hair at once and then regrow it. In fact, at a given moment 80 to 90% of the hairs are growing, 1 to 3 are in involution and 5 to 10% are resting.

Naturally, each day 75 follicles end telogen and are released, but 75 more enter anagen, starting to grow. So, how come some people are losing hair?

Hair loss can be caused by a number of factors and is roughly divided in scaring and non-scaring alopecia (a.k.a. hair loss).

Scaring alopecia is when you lose hair because some damage was done to your hair follicles that made them scar. Because they are now scared, they can’t grow hair. This happens, for instances, in burns (including does caused by perms), by pulling hair and applying chemicals to your scalp. This is partially responsible for hair loss in everyone, unless they don’t wash their hair and don’t go to hairdressers/barbers.

Non scaring alopecia is when the cause does not relate to scars. It is the case of alopecia caused by chemotherapy and, most commonly, androgenic alopecia, a mix of genetic factors and environmental triggers.

In androgenic alopecia there is a genetically triggered shortening of anagen, the growth phase. This causes hair to grow thinner and thinner, eventually falling. The activation of the genes that cause this events, is done by DHT.

Current treatments to alopecia try to block DHT from activating the genes. This means that hair will begin growing strong again. Because no hair follicles were lost (as it is non scaring), hair that was already lost will start growing again and hair that was thin will grow thick again.

Of course that treatment cannot destroy the genes, so hair loss treatment is for life, because if you stop it, DHT will activate the genes and hair will fall again.

If you are interested in stopping or preventing hair loss and regrow lost hair, go to http://www.not-bald-anymore.com/

Miguel Oliveira
http://www.not-bald-anymore.com