The Hair Growth Cycle

Did you know we shed close to 100 strands of hair per day? Yet our hair continues to lengthen. Hair grows in a cycle, each follicle functions as an independent unit so that hair does not shed all at once. Let’s break down each phase of the hair cycle and what could affect hair growth.

Hair Growth Phases

At any given time, each strand of hair may be in one of the four phases of growth.

Anagen: 

This is the growth phase, in which the hair cells actively divide. On the scalp, the average period is 3–4 years.

Catagen: 

This is a transitional phase, in which the cells are no longer dividing and hair regresses to form a club hair that moves closer towards the surface of the scalp. This usually lasts approximately 2 weeks.

Telogen:

This is the resting phase during which the regressed or club hair remains in the follicle. This usually lasts 1–4 months. 

Exogen:

Exogen used to be considered a part of telogen, but more recently has been recognized as a separate phase in which a new anagen hair forms in the follicle and dislodges the prior resting hair, such that the old hair is shed and a new follicle starts to grow in its place. The average person loses 50–100 hairs per day.

Hair growth is affected by Age and Environment

As we age, the percentage of hair in the growth cycle decreases. It decreases even faster in people with hereditary baldness, alopecia and female pattern hair loss. Your hair cycle can even be affected by environmental stressors such as medications or chemotherapy. These can interfere with the cell division that allows hair growth. This leads to a thin shaft which breaks within the follicle.

How much hair is in which phase at any given time? 

It is said that between 85–90 percent of all scalp hairs are in Anagen phase, 1 percent are regressing and the remaining percent are resting or being shed. This is why you’ll typically see an average of 50–100 hairs falling out per day. 

Hair Growth...how fast for typical growth?

The average rate of hair growth is approximately ½ an inch per month. However, this doesn’t mean that your hair can’t grow faster or slower than that. Anywhere from 0.6cm to 3.36cm is considered normal growth. This rate can vary depending on age, hormones, genetics and illness. In order to support a healthy follicle and normal hair growth, it is recommended that you consume healthy diet along with hair vitamins full of iron, protein and vitamin B.

Hair Growth Stimulation?

As mentioned previously, certain medications, chemotherapy and even emotional distress can lead to sudden thinning. On the other hand, female pattern baldness is a genetic cause, resulting in a more gradual thinning. The treatment for each of these differs—ranging from over-the-counter shampoos and topical treatments to changing your environment. Some of the most common ways to stimulate hair growth include using vitamin-based shampoos, applying treatments containing minoxidil or aminexil or adjusting your diet to promote healthy hair.