Hair forms in a pouchlike structure below the skin called a hair follicle. What we see as hair is actually the hair shaft, which is the keratinized, hardened tissue that grows from the follicle. Humans have more hair follicles per square inch than most higher primates, including chimpanzees and gorillas. Because most of this hair is fine and pale (called vellus hair), it usually isnt visible to the naked eye. Consider this: the forehead has more hair follicles than any other part of the body. The thicker, fully pigmented hair most people consider "real hair" is called terminal hair. This hair is found on scalp, eyebrows, legs, backs, underarms, and genital areas. This is the hair the laser treats.
Everyones hair grows differently, depending on age, weight, metabolism, hormones, ethnicity, medications, and other factors. But all hair goes through three distinct growth phases:
Active growth phase (called the anagen phase), which lasts up to several years. At any given time, the majority (85%) of our body hair is in this phase. During anagen, the hair has an abundance of melanin.The laser most effectively disables hair that is in the active growth (anagen) phase. Because all the hair in a treated area may not be in the anagen phase, more than one laser treatment may be necessary to remove the hair that subsequently enters the growth phase.