Normal hair cycle
A hair grows from a follicle underneath the skin. Each hair stand derives its nutrition from the base of the hair follicle. Hair loss is a natural process of the hair growth cycle; old hairs fall to give place to the new. But if the rate of hair fall exceeds the rate of hair growth, then problems arise, and one can experience the visible signs of hair thinning.
Between growing and falling, each hair undergoes four successive stages; that is the anagen phase, the catagen phase, the telogen phase and finally the exogen phase.
Anagen or Growing phase :
The growing phase actually determines our hair length and lasts up to two to seven years. The hair grows half an inch a month, and the rate of growth is higher in summer than in winter. The cells in the root of the hair divide to add length to the hair shaft.
Catagen or transition phase :
During this phase, the hair follicle shrinks and gets detached from the dermal papilla. It lasts for about ten days. In this stage, a club hair is formed, which is formed when a section of the hair follicle attaches to the hair shaft, thus limiting blood supply to the shaft. This club hair only brings in the third stage or the telogen stage.
Telogen or resting phase :
About 10 to 15% of the total hair remains in this phase, which is essentially a resting phase. It lasts for about 3 months. These are the hair one looses when shampooing or combing one’s hair. This is the phase that gets heavily influenced by nutrition and/ or diet; for example, if one follows restrictive dieting for 6 weeks, or experiences high fever, then he/ she may be affected by telogen effluvium (or diffuse hair fall).
Exogen or new hair phase :
This is a component of the resting phase where the new hair starts to gain roots and grows profusely.
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