Before you learn how laser hair removal works, you need to understand how hair grows. Hair grows from deep within hair follicles, which are thin cavities embedded in the dermis. Hair does not grow continuously, but grows in a three-phase cycle. While the rate at which hair grows differs by individual, the length of the hair growth cycle generally depends on the type of hair. For example, the active growth phase of the hair on your head may last several years, while hair on the body has an active growth phase that may last only a few months.
Each growth cycle includes an Anagen, Catagen, and Telogen phase. During the Anagen phase, the hair grows actively from the follicle. The next phase of the growth cycle is the catagen phase. This is a short transitional period in which the hair stops growing and the hair follicle shrinks in size. The follicle breaks away from the dermal papilla, which supplies nutrients to the hair follicle. The dermal papilla then regresses. The last phase of the growth cycle is the telogen, or resting phase. During the telogen phase, the hair follicle reattaches to the dermal papilla, at which point the follicle re-enters the anagen phase. As a new hair begins to grow, the old hair is pushed out of the follicle.
During laser hair removal, a laser emits light energy that travels through the skin and is absorbed by the pigment in the hair follicle and hair shaft. Pigments are the substances that give skin and hair its color. The laser works by selective photothermolysis, which means that the light energy is selectively absorbed by pigmented hair follicles. The energy, or heat, from the CYNOSURE ELITE PLUS laser damages the hair follicle, which impairs its ability to grow. Hair follicles that are in the anagen, or active growth phase, absorb and respond the best to the laser treatments. This is the reason it typically takes multiple treatments to achieve the best results. Its important to “catch” your hair in this active growth phase when you are receiving treatments.
During the procedure, the specialist will guide the laser over the treatment area. As the laser pulses intermittently, it delivers light energy, which travels through the skin and is absorbed by the hair follicles. Those hair follicles that absorb energy, or heat, from the laser will be damaged. Hairs that were present in the follicles at the time of treatment will fall out over a period of two weeks and future hair growth will be impaired.
As not all hairs are actively growing at the same time, a single procedure will not treat all of the hair follicles in the area. As the follicles in the transitional and resting periods return to the active growth phase, you may notice some hair regrowth but not as thick as it was before the treatment. This regrowth will become thinner and lighter with each subsequent treatment until there is little, to no hair at all.