HAIR GROWTH CYCLE
It's good to learn about our "enemy" before having a laser hair removal treatment. You should take a closer look at the hair structure to better understand mechanism occurring in hair follicles.
The main hair building block is creatine, a type of protein produced in the epidermis.
The hair structure consists of a shaft and a root hidden under the skin. It's placed in a kind of bag called a hair follicle. The sebaceous gland is attached to it. At the bottom of the hair follicle is a hair bulb. The bulb contains matrix cells which are responsible for hair production and growth. This is the only "living" part of hair. The hair shaft extending above the skin surface is a completely "dead" structure. The matrix includes melanocytes and dividing epithelial cells. The former produces melanin and the hair colour, while the latter is responsible for hair growth. The more melanin is produced, the darker hair colour is. Melanin is also responsible for the skin tone and the ability to get tan when the skin is exposed to the sunlight. The hair bulb is located on the papilla.
Inside the papilla are numerous blood vessels which provide the matrix cells with building and nourishing substances.
Individual human hairs don't grow simultaneously. The hair's life cycle consists of three phases: growth phase (anagen), transitional phase (catagen) and resting phase (telogen). Only hair in the growth phase reacts positively to the laser beam. The hair follicle with the matrix at the bottom and the papilla need to be destroyed in order to remove hair permanently.
is a phase when hair actively grows.
The hair root is strictly connected to the hair papilla. Properly nourished, the matrix divides its cells, making the hair grow above the skin surface. Anagen (as for the hair on your head) lasts from 2 to 6 years. As far as the body is concerned, it's much shorter. Face anagen lasts 6 weeks and leg anagen 12 weeks.
In this phase the laser beam may go through hair (melanin is a conductor) directly to the papilla – heating it up and destroying. Due to such heat, the hair is burnt. About 2 or 3 weeks later, it crumbles and sheds. Hair in this phase will never regrow because the matrix, which is cut off from building and nourishing substances produced by the papilla, atrophies and is not able to regenerate.
is a transitional phase, when the hair bulb separates from the hair follicle and goes up. Next, processes related to hair production are slowly stopped and so is the hair growth. Melanin is not produced any more so the colour in the lower part of hair fades. In this phase the laser beam doesn't go directly through the papilla. Only a small amount of energy reaches there, but it isn't enough to completely destroy the hair. The hair will be obviously burnt and shed but the hair follicle and papilla are not damaged, so the cycle continues to the telogen phase and then anagen. As a result, a new hair is produced.
is a resting phase, the last one in the hair's life cycle. Here, the hair starts dying and is slowly removed from the skin. Laser is completely ineffective for hair in this phase (lack of energy flow). The papilla and the matrix are in the resting phase, waiting for a signal from the body to reactivate the whole cycle and start producing a new hair.
As you can see, three phases of hair growth determine the frequency and number of treatments which should be performed to remove hair permanently. You need minimum three regularly performed treatments with 2-month intervals to destroy 80-92% of unwanted hair. Long intervals between the treatments make the results worse (hair could change its phase). The human body is able to regenerate so after some time hair papillas can reappear. That is why we suggest doing a retreatment once or twice a year to keep your skin smooth.