Laser hair removal is one of our most popular treatments at Dr. Lipton’s practice. We often get questions from patients wondering why they need something like six sessions to get rid of their unwanted hair? Doesn’t the laser zap the hair you can see?
Well, the laser does hit every hair in the target areas. The question is — are those hairs ready for it?
Here’s some information on how the human hair growth cycle affects the efforts to remove it with laser energy.
The Cycles of Hair Growth
You may not know this, at least you’ve probably not spent a great deal of time thinking about it, but human hair has three phases to its growth cycle. Being in the correct phase matters when it comes to laser hair removal. Oh, and we have around 5 million hairs on our bodies.
The hair on your head grows about one-half inch per month, faster in the summer than in the winter. Your body hair doesn’t grow as fast, but it has the same hair cycles. The anagen phase is a growing phase. In this phase, the hair is growing and healthy. It is actively anchored into the hair follicle. This phase is when laser hair removal is effective. Unfortunately, only around 20 percent of our hair is in anagen phase at any time, and every hair on the human body operates on its own, meaning there is no rhyme nor reason to which hairs are in which part of the growth cycle. The anagen phase can last for three to four months on body hair and five to seven years on your head hair (this is why we don’t grow long, nasty body hair).
When the anagen phase ends, the catagen phase takes over. This is a transitional phase from growth to rest. This phase lasts around three weeks for body hair. Lasers are not effective during this phase, as the hair base down in the follicle is shrinking and dying, and the hair is separating from the follicle.
Next, the hair enters the telogen, or dormant, phase. Up to 80 percent of our hair can be in the telogen phase at any time. This phase lasts from five to six weeks for body hair. In this phase, the follicle has shortened by about one half its length from the anagen phase. This makes the entire hair shaft move upwards. At some point, the hair will fall out. This will then begin the move back into the anagen phase, as a new hair forms in the bottom of the follicle. Hair hit with laser energy in this phase has no effect. The hair is already basically dead, and so it is no longer really a part of the follicle. And damaging the follicle is key.
Why you need multiple laser hair removal appointments
To be effective, the laser energy must hit a growing, active hair. Then, the energy is absorbed by the pigment in the hair, and it travels down into the follicle and damages it. This damage precludes the hair from growing for a period of months to years, depending on the person. Because only 20 percent of our hair is in the anagen cycle at any time, and because we have no idea which hairs are in which cycles, there’s no way to tell how effective an individual session with the laser will be. By using multiple sessions, we are able to hit more and more hair when it is in the anagen cycle.