Hair Growth Cycle
Hair is made up of a protein known as keratin which is present in the hair follicles. The follicles have a function of producing new hair cells which push out the old dead cells. At all times 90% or more of the hair on the scalp is in growing phase. The pace of hair growth differs for every single hair on the scalp. Each and every hair follicle follows their own hair cycle which may be influenced by different factors such as age, race, nutrition, illness, etc.
An interesting fact is It is just because each hair follicle goes through a different hair growth cycle, that we shed only a few number of hairs per day. If all the hairs on the head would go through the same hair growth cycle, all the hair would have fallen at once.
Between starting to grow and falling off, each strand of hair goes through three stages:
Anagen or the growing phase:
This is the phase where the hair grows at a rapid rate from the follicle. This phase lasts for around 2 to 6 years. It is a very important phase for hair growth as hair length depends on the duration of this phase.
Catagen or hair growth stopping phase:
This phase lasts for about 2 weeks and is termed as a regressive phase. During this phase, the hair stops growing and the follicles start contracting.
Telogen or Resting phase:
This is the last phase of hair growth cycle, the hair remains as it is with no further changes. This phase may last for about 2 to 4 months.
After this period the hair follicle becomes active again developing new hair and forcing old follicle out. At any given time, 90% of hair is in Anagen phase and 10% in Telogen phase. A reversal of the ratio results in thinning of hair.