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What is the hair growth cycle?

Hair Growth And Breakage

Marilyn Sherlock (Trichologist) gives expert video advice on: Can you effect the speed of the hair growth cycle?; How long does it take for hair to grow?; How can hair breakage be prevented? and more...

What is the hair growth cycle?

The hair growth cycle is a 5 year one, generally, for Europeans. It can be as little as two years, or as much as seven years, depending on your race. That is the actual growing phase, which we call the anagen phase. At the end of that anagen phase, the blood supply to the hair is severed. The hair then rests for two weeks in what we call the catagen phase. At the end of that two weeks, the hair then moves onto the third and final phase, which is the telogen phase. The hair is then, at that stage, waiting to fall out. It can't get out because of its shape and the way its attached to the hair follicle, so it sits there for approximately three months, and then either falls out or is pushed out by the next hair follicle.

Can you effect the speed of the hair growth cycle?

The hair growth cycle can be neither increased or decreased as yet.

How long does it take for hair to grow?

Hair grows at approximately 1.25 to 1.5 centimetres per month. That means an average of 15 centimetres a year, which means that very long hair may be as old as 4 or 5 years. This of course affects the way you care for it because the hair becomes much more fragile. There are also some people who will grow their hair much slower that that, at less than a centimetre per month. Again, the average, as I previously said, is approximately 1.5 centimetres per month.

How long does a hair live?

The hair lives, if you're Afro-Caribbean, or of African origin, for perhaps only 2 years, maybe 3. In Europeans, it's approximately 5 years. For Asians it can be as much as 7 years. here are of course variants between those because of mixed race, but that is a guideline as to the hair life cycle, the life span of hair.

What is the structure of the hair?

The hair is made up of a cortex, the central core of the hair. Sometimes there is a hollow middle to the hair, which is called the badulla, but it isn't present in all hairs. On the outside there is a protective sheath known as the cuticle. The cuticle is there to protect, to hold moisture; the cortex is the main body: it is elastic, it will bend, it will take in colour, it will take in perms, and that is the sensitive part. Without the cuticle, the cortex can be damaged very readily.

Why does hair breakage happen?

Hair breakage happens due to the natural or chemical weathering of the hair. The hair is made up mainly of the central core, which is called the cortex and is made of water, which is very elastic. The hair is protected by the hair cuticle, which is a form of scales on the outside of the hair shaft. If those scales wear out, which they do - through natural weathering, curling, hair brushing, swimming, sunshine, central heating, as the hair gets older - it will become quite delicate. The cuticle will be removed and the moisture exposed, so the moisture in the hair is no longer retained, and so the hair becomes brittle. This can also happen if the hair is chemically over-processed. It will remove the cuticle from the hair, allowing the central moisture to escape. Breakage of the hair takes place at the point of interest there. Even after the hair feels dry, having washed it, it actually contains something like 10% water.