The Hair Growth Cycle

The average head has around 100,000 follicles and each of these performs its own Hair Growth Cycle completely independently of other follicles on the head. 

There are 3 main stages to the Cycle which lasts, on average, 3-4 years:

•  Anagen (growth) phase. Accounts for around 85-90% of the follicles at any given point and lasts for approximtely 3 years, before the follicle transitions to 
• Catagen (transition) phase. Acconts for around 1% of follicles, and lasts around 2 weeks.
• Telogen (shedding) phase. Accounts for around 10-15% of follicles at any one time and lasts for roughly 3-4 months. The hair sits in the follicle, inactive and no longer growing, waiting to be shed. After this, the hair is shed and a new hair is beginning to grow behind it, ready to re-start the Hair Growth Cycle all over again.

Hairs exiting the follicle, to make way for new growth at the end of the Telogen phase, are shed as we go about our daily lives. Most often they fall unnoticed, but can be seen more readily if they cling to our clothing, or collect in brushes, combs or drains as we brush, wash and style our hair. 

It is normal to shed around 100-150 hairs a day, although this is an 'average' figure which can vary between individuals. Levels can also fluctuate depending on factors such as wearing hair in banded styles, eg. ponytails, where the hair is physically prevented from falling, or when hair has not been brushed or washed for a longer than usual duration.

If the level of hairs lost is higer than normal, it is usually nothing to be overly concerned about if it is only for a short period of time. However, if the higher level of loss is sustained over a longer period, this could be a sign of a hair growth disruption.

Irrespective of the type or cause of the hair growth disruption, the Hair Growth Cycle is almost always negatively affected. 

Systemically, this results in an imbalance in the phases of the Cycle on both an individual follicular level and across the head as a whole, through:

• Foreshortening of the growth (Anagen) phase. As the longest and most heavily populated part of the Hair Growth Cycle, shortening of this phase has serious repercussions across the entire Cycle.
• Early induction of the transition (Catagen) phase. Where follicles exit the growth phase prematurely, the transition phase is induced sooner than normal.
• Extended resting (Telogen) phase. With more follicles prematurely reaching the resting phase of the Cycle, levels of shedding are increased. Simultaneously, the prolongation of the resting phase reduces the number of hairs completing the Cycle to return to Anagen growth, leading to poor regrowth and/or follicles falling dormant.

Visually, the results of the disruption can present in many ways, such as hair that no longer reaches its growth potential, excessive levels of shedding, general thinning over the entire head or in specific patches, or areas where the follicles fall dormant and no longer produce hair.

These changes are all resultant of a depletion of key signalling molecules which are usually present within healthy hair follicles. The molecules - called Proteoglycans - modulate the cycling behaviour of the follicles, ensuring that they complete the Hair Growth Cycle in a proper and timely manner, therefore, their presence is vital in ensuring hair quality and hair growth.

Successfully addressing hair growth disruption requires support and normalisation of the Hair Growth Cycle through the restoration of the levels of these key molecules.