Here at The Griffin Center of Hair Restoration and Research we understand that properly diagnosing and treating any of the myriad causes of hair loss requires a fundamental understanding of every aspect of hair growth. In our last blog, we talked about the anatomy of the hair follicles, the tunnel-like segments of the epidermis that are the source of all of your body’s hair. This week, we’ll delve more deeply into the hair growth cycle itself and explain just how your hair comes into being.
About 5 million tiny hair follicles cover your body, lying just underneath the outermost layer of your skin, with about 100,000 on your scalp alone. At the base of each follicle is the papilla, which contains the tiny blood vessels that nourish the growing cells in the hair bulb. These cells divide every 23 to 72 hours, significantly faster than any other cells in the body, to form long chains of a fibrous protein called keratin. These fibers form the shaft of the hair, which slowly pushes up through the skin as it grows, passing the sebaceous (or oil) gland along the way. This sebaceous gland is vital because it produces sebum, which conditions the hair, keeping it shiny and soft.
By the time the hair has grown long enough to poke through the skin, the emerging shaft itself has died, but the bulb deep inside the follicle continues to grow and nourish new hair. This growth, however, does not occur all at once. Instead, at any given time, a random number of hairs will be in one of three distinct stages of hair growth called the anagen, catagen, and telogen phases. During the anagen phase, the cells in the root of the hair are dividing rapidly and new hair is growing at a rate of about 1 cm every 28 days. Scalp hair stays in this active phase of growth for two to six years, while the hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30 to 45 days, explaining why they are so much shorter than scalp hair. After the anagen phase comes the transitional catagen phase, a relatively short (two to three week) period when growth stops and the outer root sheath shrinks and attaches to the root of the hair, forming a “club hair” which is easily shed. At this point, the hair enters a roughly 100-day telogen phase, where the hair is completely at rest. During this time the follicle begins producing a new anagen hair shaft, which pushes out the fully formed club hair still resting on the surface. Anywhere from 50 to 100 telogen hairs are naturally shed each day. However, in a process referred to as telogen effluvium, an abnormal amount of hairs enter the telogen phase prematurely and are shed simultaneously. This is caused by external or internal stressors on the body and hair, such as hormone changes, thyroid problems, and even extreme mental stress.
If you have additional questions about your own hair loss, or are interested in any of the hair restoration treatments we offer at The Griffin Center, please contact Dr. Griffin or Dr. Curtis to schedule a consultation. Be sure to also visit our website and follow us on Facebook, Twitter, and Google+.