It is useful to understand the Hair Growth Cycle in order to recognise and understand many of the problems you may encounter with your hair.
The growth cycle of a hair consists of 3 stages:
Normal hair follicles undergo periods of growth (Anagen) followed by regression (Catagen), resting (Telogen) and evacuation (Exogen) followed by regenesis (‘new’ Anagen).. No hair therefore grows continuously. This hair cycle, which dictates the ultimate hair length attainable by an individual, is explained under the following headings:-
ANAGEN (GROWING) STAGE
Your hair grows around 1 – 1.5cm per month, faster in summer than in winter
- The anagen stage is the growing period of a hair follicle.
- This stage typically lasts about 3 to 5 years. o Asian hair can last 5-7 years
- Full length hair can be upto 100 cm long
CATAGEN (INTERMEDIATE) STAGE
At the end of the Anagen phase, your hair enters the Catagen phase
The catagen stage is the intermediate period of hair growth.
- Hair follicles prepare themselves for the resting phase.
- It lasts around 1-2 weeks.
- During this phase, the deeper portions of the hair follicles start to collapse.
TELOGEN (RESTING OR SHEDDING) STAGE
During the telogen phase each hair is released and falls out
- The telogen stage is the resting and shedding period of the hair cycle.
- The follicle remains inactive for 3 to 4 months.
- At the end of this period, older hairs that have finished their life will fall out and newer hairs will begin to grow.
Hair loss, hair thinning and problems with hairgrowth occur when the growth cycle is interrupted/disrupted. This can be triggered by conditions such as nutritional and medical situations, illness or stress. For instance 6 weeks after intensive dieting or stress you can experience hair fal. This occurs because the growing stage (Anagen) is cut short and hairs enter the falling (Telogen) stage at the same time.
Timespan of the Hair Growth Cycle
- The anagen phase constitutes about 90% (1000 days or more) of the growth cycle.
- The catagen phase (10 days) and telogen phase (100 days) constitute only 10% of the hair growth cycle.
- During the catagen and telogen phase of the hair growth cycle, as hairs are at the shedding and rest-from-growth period, no bald spots are shown as hairs are randomly distributed over the scalp.
Human hair cycles through three stages:
There is a fourth stage which we refer to as Exogen: The process of hair shedding. Whereas hairs may be shed at any stage of the cycle, the majority of shedding occurs during the ‘new’ Anagen phase.