Hair Loss NewsThe life cycle of a hair follicle
13 June 2017 · 3 min read
To be able to understand the ins and outs of hair growth and hair loss, you’ll need to have a basic grasp on the hair growth cycle. Hair growth runs in three phases, anagen, catagen and telogen. The hair follicle is the skin organ that produces the hair. The shape of which has a direct effect on the shape and texture of an individual's hair.The anagen phase is the phase in which the hair grows. It grows around half an inch every month, and it grows quicker in summer than in winter. Each anagen phase lasts around 3 to 5 years, and the average maximum length of one strand of hair is around 18 to 30 inches. Around 90% of the hair follicles in your scalp will currently be in the anagen phase, which is why, despite losing a significant amount of hair every month, most won’t even notice.The catagen phase is the shortest phase of the hair growth cycle. It lasts about 10 days and is often referred to as the transition phase. It is during the catagen phase that club hairs are produced – the part of the hair follicle that is in contact with the lower section of the hair becomes attached to the hair shaft, which then cuts off both the blood supply and the cells responsible for producing new hairs, converting the original hair strand to a club hair. Once the hair follicles have formed the club hair, the next phase begins.The telogen phase can be referred to as the shedding or rest phase. When the hair follicle is in telogen phase, it rests and releases the hair, causing it to fall out. The follicle then remains inactive for three months, and then the cycle begins once again. Obviously, every hair is at a different stage of the hair growth cycle – otherwise, all of your hair would fall out at once. Around 50 to 100 hairs are shed from a healthy scalp every day, which is why finding hair in your brush is normal rather than a warning sign. About 10% of your hair follicles will be in telogen phase at any one time.The hair growth cycle isn't the same for every part of your body. Even though the cycle takes around 5 years on the scalp, eyebrow hair follicles only take four months to complete one cycle, which explains why the hairs are so much shorter than on your head.
Understanding the cycle explains two things that worry people unnecessarily. A heavy shed two or three months after illness, surgery, childbirth or acute stress is usually telogen effluvium, where an unusual number of follicles enter the resting phase at once, and it generally recovers on its own. And the shedding that follows a hair transplant is the same mechanism: the shaft lets go while the follicle stays put and resets.
Pattern hair loss is different. There the follicle itself shrinks with each cycle until it no longer produces a usable hair. If you are seeing a widening parting or a receding hairline rather than a temporary shed, book a free video assessment and we will tell you which one it is.
