Getting to Know Your Hair: The Hair Growth Cycle

Dr. Edmond Griffin and Dr. Ashley Curtis of The Griffin Center of Hair Restoration and Research always say: when it comes to hair restoration, it’s the details that make the difference.  This is true not only because every patient is unique and requires a customized solution to their individual concerns, but also because hair itself is much more complicated than most people realize.  Over the last several months, in our “Getting to Know Your Hair” blog series, we have explored the anatomy of both the hair follicle and the hair shaft itself, but these are really only the beginning of the story.  In order to truly understand how hair works, we will also need to delve into the hair growth cycle.

Getting to Know Your Hair The Hair Growth CycleThe average scalp starts out, on average, with approximately 100,000 individual hair follicles, and each one of these follicles is constantly undergoing a regular cycle of growth, shedding, and re-growth.  This means that the average, healthy person naturally sheds between 50 and 100 hairs from the head every day.  However, this loss goes largely unnoticed since, unlike other mammals, human hair growth and shedding is random, not seasonal, so the follicles are almost never in the same phase simultaneously.  More likely, at any given time a random number of hairs will be in one of three distinct stages of hair growth and shedding: the anagen, the catagen, and the telogen phases.

Anagen Phase: Aggressive Growth

During this phase, the cells in the root of the hair are dividing rapidly, and the hair is growing about half an inch per month, or six inches per year.  This new hair pushes through the dermis to the surface of the scalp, dislodging older hair along the way.  Scalp hair can remain in an active growth phase for anywhere from two to six years, depending on an individual’s genetics, which is why some people find it easier to grow their hair longer than others.  At any given time, about 85% of the hairs are in the anagen phase.

Catagen Phase: A Brief Transition

After the anagen phase comes the transitional catagen phase, a relatively short period, lasting about two to three weeks, when growth stops and the follicle effectively renews itself.  During this phase the outer root sheath shrinks and attaches to the root of the hair, forming a “club hair” which is easily shed.  This shrinking of the hair follicle is similar to what occurs during common genetic pattern hair loss, or androgenetic alopecia, but in the case of the catagen phase is only temporary.

Telogen Phase: Shedding to Make Way for New Growth

When the hair enters the telogen phase, it remains completely “at rest” for roughly 100 days.  During this time the follicle begins producing a new anagen hair shaft, which pushes out the fully formed club hair that is still resting on the surface.  Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root.  Only about ten percent of the hairs on the scalp are in the telogen phase at any one time, except in cases of telogen effluvium, a relatively uncommon form of hair loss that can be brought on by significant physiological stress.

Understanding the regular pattern of hair growth gives us important insights into the progression and underlying causes of hair loss, so it is something that the hair restoration experts at The Griffin Center spend a great deal of time studying.  If you are concerned about your own hair loss, or are interested in learning more about the many surgical and non-surgical hair restoration options that are available, follow us on Facebook, Twitter, and Google+ to get the latest news or answers to your questions about hair restoration or contact The Griffin Center of Hair Restoration of the Griffin Center for Women’s Hair Loss so that we can schedule an appointment for a full hair loss consultation and diagnosis.