Tuesday, April 7, 2009
The Science is Part I of a 4 part series geared at dispelling the myths, providing the facts and suggesting techniques for optimal hair growth. The topics to be discussed later are The Enemy, The Friend and The Technique.
Fact or Fiction? Anybody can grow long hair with proper care. FICTION-- Here's why:
Each individual has a unique hair cycle which accounts for the length of their hair. A complete hair cycle consists of 3 phases: anagen, catagen and telogen. Anagen is the active growth phase of the hair cycle. The duration of the anagen phase is 3-7 years depending on the individual. In contrast, the rate of hair growth is generally the same for everyone. Hair usually grows at a rate of one centimeter a month; although there are factors that can affect the rate of growth ie season and health. The anagen phase is initiated in the follicle embedded deep in the scalp. Over time, the follicle gradually rises to the surface presenting the hair shaft.
The catagen phase is the rest period for the hair lasting approximately 2-4 weeks. During the catagen phase, the hair is no longer actively growing, however; the follicle is still moving towards the surface of the scalp. The follicle also begins to shrink in size marking its near demise.
The final phase of the hair cycle is the telogen phase. This is the period of time in which the follicle sheds mature hair. The shedding period lasts about 3-4 months. In the telogen phase, hair is either shed naturally or pulled out painlessly in the typical grooming process of shampooing, combing, brushing, etc. With the shedding of old hair, the follicle is ready to cultivate the growth of new hair; thus marking both the ending and beginning of the hair cycle. At any given time, 90% of hair on the scalp is in the anagen phase while the remaining 10% is in the telogen phase.
The anagen phase is the segment of the hair cycle that is responsible for length. Unfortunately the duration of an individual's anagen phase is genetically determined. In other words, there is no way to alter the length of one's anagen phase nor the natural length of one's hair. Hormones play a significant role in the anagen phase and provide an explanation for the variances in hair growth between men and women. Androgen, the male hormone present in both males and females, has the greatest affect on hair growth and thickness. Oestrogen, the female hormone also present in both sexes, decrease the rate of hair growth, yet extend the growth period. In pregnancy, the oestrogen levels are much higher which is why hair tends to grow longer in those 9 months. Ultimately, the balance between androgen and oestrogen in individuals regulates hair growth.