SCIENCE

Before removing hair, it helps to know about the different types of hair on our bodies. All hair is made of keratin, a hard protein that's also found in your fingernails and toenails. Hair growth begins beneath the surface of your skin at a hair root inside a hair follicle, a small tube in the skin.

Hair growth has three phases

1. Anagen (active)
2. Catagen (regression)
3. Telogen (resting)

The length of the whole growth cycle depends on the body part, and lasts anywhere from 4 to 12 months. Hair reduction is considered permanent when a significant amount of hair does not return for a period of time longer than the complete growth cycle.

You have two types of hair on your body. Vellus hair is soft, fine, and short. Most women have vellus hair on the chest, back, and face. It can be darker and more noticeable in some women than others - especially women with darker complexions. Vellus hair helps the body maintain a steady temperature by providing some insulation.

Terminal hair is coarser, darker, and longer than vellus hair and is the type of hair that grows on your head. When a teen reaches puberty, terminal hair starts to grow in the armpits and pubic region. On guys, terminal hair begins to grow on the face and other parts of the body such as the chest, legs, and back. Terminal hair provides cushioning and protection.

The Chromophore

The hair germinative apparatus

Epidermal melanin

Differential Absorption of Laser Energy based on melanin  concentration

Differential Cooling - Hair follicle vs. epidermis

Multipulsed lasers take advantage of the faster heating and slower cooling of the hair follicle vs. the epidermis