Permanent Laser Hair Removal

To achieve permanent laser hair removal, it is important to understand the
growth cycle of hair. Laser treatment does not kill all hair in one
treatment because hair is more suscetipble to damage in it's earlier stages
than it is in it's later stages of growth. Thus, laser hair removal needs to
be performed at intervals.

Following is a comprehensive overview of the hair growth cycle and the
effectiveness of laser hair removal (extracted from Advanced Laser Clinic).

How Does Hair Grow?
The hair shaft forms from a pouch-like structure located below the skin surface which is called a hair follicle. What we see
as hair is actually the hair shaft, which is the hardened tissue that grows
from within this follicle. It is this thicker, pigmented, visible hair that
is targeted by the laser.

Everyone's hair grows differently, depending on their age, weight,
metabolism, hormonal interactions, genetics, medications and environmental
influences. However , regardless of how these factors affect individual hair
growth, hair itself evolves or grows through three distinct phases as
outlined below :

1. The ACTIVE or ANAGEN growth phase, comprises approximately 85 % of our body hair at any given moment in time and can last up to several years. During this anagen phase, the hair shaft and follicle has an abundance of melanin or pigment and as such, is most sensitive to the laser light.
2. The REGRESSIVE or CATAGEN phase is the period during which the hair
   stops actively growing but is not shed. This phase often lasts several weeks comprising about 3 - 4% of our total body hair at any given time.
3. The RESTING or TELOGEN 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.

How Lasers Work
All Lasers emit a specific wavelength of energy or light
(both visible and invisible) which in turn is directed towards a so called
chromophobe or target cell. In the case of hair removal technology, these
laser produce a wavelength of 750-800 nm which is absorbed by the pigment or
melanin of the hair shaft and follicle . The absorption of this energy
effectively destroys the hair follicles without damaging the surrounding
skin.

So to achieve permanent hair removal, you will need multiple treatments at
set intervals to ensure that you get to the hair when it is in the first
stage of growth (Active/Anagen).