It’s All in the Cycle of Growth
- Posted on: Sep 15 2018
No one likes dealing with unwanted hair. It’s a pain, literally and figuratively. At Saltz Plastic Surgery/Spa Vitoria, we offer laser hair removal, and patients often wonder why it takes numerous sessions to really get rid of the majority of the unwanted hair.
It all comes down to the growth cycle of human hair. To help you understand why this is critical to successful laser hair removal, here’s a little primer on human hair and how it grows.
How it grows
Human hair grows from deep within the hair follicles, which are thin cavities embedded in the dermis (the skin’s second layer). In most of these hair follicles you’ll also find sebaceous glands. The sebaceous glands produce oil that keeps the skin and the hair from drying out. If you’re a teenager, you’re cussing out the sebaceous glands because their hormone-driven overproduction of oil is the basic cause of acne. For the rest of us, that oil keeps our hair and skin moisturized.
Overall, humans have about 5 million hair follicles across our bodies. Men have a few hundred thousand more than women. The only places without hair follicles are our palms and the soles of the feet. Impress your friends with that little statistic! Your hair color and ethnicity can dictate how many hairs you have on your scalp. Blondes have an average of 150,000 hairs. Redheads average around 90,000. Black- and brown-haired people have from 100,000 to 110,000 scalp follicles.
Hair doesn’t grow continuously, but in a three-phase cycle. Your rate of hair growth varies by the individual and by the type of hair. For instance, the active growth phase for scalp hair may last several years (Rapunzel!), while hair on the body has an active growth phase that may only last a few months.
Each growth cycle of each hair has three phases: anagen, catagen, and telogen. During the anagen phase, the hair grows actively from the follicle. It is anchored strongly into the follicle. The next phase, the catagen phase, is a short transitional period where the hair stops growing and the hair follicle begins to shrink. The follicle breaks away from the dermal papilla, which supplies nutrients to the hair follicle. Then the dermal papilla regresses downward. The last phase is the telogen, or resting, phase. In the telogen phase, the hair follicle grows back downward and reattaches to the dermal papilla. When this is complete, the hair follicle returns to the anagen/growth phase. As a new hair begins to grow, the old hair is pushed out and shed.
Lasers and hair
Now you see why it takes multiple laser removal sessions to really get rid of hair. The hair must still be anchored in the follicle and its pigment must be at full color. This only happens in the anagen phase. During that phase, the hair’s pigment absorbs the laser energy, which travels down the hair shaft into the follicle. There, the heat damages the follicle, stopping hair growth. Because the hair isn’t connected to the follicle in the catagen or telogen phases, laser energy has no permanent affect on it.
Heading into fall is a good time to start the necessary sessions to get rid of your unwanted hair. Then when spring rolls around, you’ll be ready to hit to pool, beach, or hot tub. Call us at Saltz Plastic Surgery/Spa Vitoria in our Salt Lake City office, (801) 274-9500, or our Park City office, (435) 655-6612, to make your appointment.