How does the laser work?
Used for 30 years and supported by numerous scientific publications, permanent laser hair removal has long since proven its worth, both in terms of effectiveness and safety.
Permanent laser hair removal is a method that uses light energy to destroy hair follicles permanently.
A laser beam emits a very intense beam of light of a specific wavelength that penetrates the skin to reach the hair follicles.
The wavelength of the emitted light determines its target. For hair removal, the target is melanin. Since melanin is present in both the skin and the hair follicle, this explains both its effectiveness (destruction of the follicle) and its risks (skin burns).
The basic principle is based on " selective photothermolysis ": once absorbed by melanin, the light is transformed into heat and destroys the hair follicle.
This can be summarized as follows:
1. A laser beam emits intense light of a specific wavelength.
2. This light passes through the epidermis and is absorbed by the melanin present in the hair.
3. The light energy absorbed by melanin is converted into heat.
4. This heat spreads along the hair to the hair bulb.
5. High temperature destroys the germinal zone of the bulb, thus preventing hair regrowth permanently.
THE HAIR CYCLE AND ITS IMPACT ON TREATMENT
The hair growth cycle corresponds to the different stages in the life of a hair, from its formation to its shedding. During this cycle, hairs go through three phases:
1. The anagen phase : this is the active growth phase where the hair is attached to the follicle.
It lasts from a few weeks to a few months.
2. The catagen phase : this is a transition phase where the hair gradually detaches from the follicle.
It lasts approximately 2 to 3 weeks.
3. The telogen phase : this is a resting phase where the hair eventually falls out. It lasts 2 to 6 months.
A new hair growth cycle can begin at the end of this phase.
The phenomenon of photothermolysis only occurs on hairs in the growth phase (anagen phase). They then contain the most melanin and their bulb is in contact with the germinal zone which produces the hairs.
Since not all hairs are in this phase at the same time, several sessions are necessary, generally spaced 6 to 8 weeks apart depending on the area treated and the number of sessions already carried out.
At any given time, approximately 20% of hairs are in the anagen phase. This percentage depends on the area being treated. Therefore, about 20% of hairs will be destroyed per session.
The time required for all the hairs in a given area to go through the three phases of the hair growth cycle corresponds to the complete hair cycle for that area. In theory, this will be the minimum duration of the laser hair removal protocol. This duration varies according to several factors, including the location, hair type, and individual characteristics (women, men, hormonal imbalances, age, etc.). Here is an estimate of the average durations for different areas of the body:
Legs, arms and armpits: Total cycle duration: 6 months to 1 year.
Beard (in men): Total cycle duration: 1 to 3 years.
Bikini line: Total cycle duration: 1 to 2 years, on average.
Now you understand why permanent laser hair removal is so effective:
- only works on pigmented hair
- requires several sessions (7 on average)
- the total duration of treatment is 1 to 2 years.