Just like other biological processes, hair growth is in cycle. The growth phase of hair normally continues for 2-6 years. Hair life cycle is divided into three stages such as Anagen phase, Catagen phase and Telogen phase. A ratio of about 85% anagen hair, approximately 1% catagen hair and about 14% telogen hair is considered as normal situation. A hair follicle can produce new hair about 20 to 25 times. Your hair is replaced several times during entire lifetime.
During the anagen phase, there is continuous production of protein and keratin. The hair shaft is produced and pushed in upward direction to its natural length during this phase. This growth phase lasts from 3-5 years and represents the development of about 90% hair. At the end of this phase, blood supply to the hair bulb becomes slow and gradually stops.
The catagen stage is also called as transitional phase. During this stage, structural and chemical changes take place in the hair follicle. The hair growth is stopped and it remains in this stage for about 2-3 weeks. Then, they move to the next stage.
The talogen phase is the last stage in hair life cycle. The development of the hair is stopped. The hair remains attached to the scalp for about 3 months on your head. Then, it is replaced by the budding hair present in the anagen phase. It starts to grow from the same hair follicle. These replaced hairs get thinner and finer with aging. In most cases of baldness, the hair follicles are blocked and there is no replacement for the fallen hair. Normally, any person shed up to 100 hair every day.
Hair life cycle starts even before our birth. Hair growth can be about 1 inch per month. It is faster during summer and slower during the winter. The rate of hair growth becomes slower with aging. Some of the things that can influence the hair growth are hormones, vitamins, nutrition and emotional states.