Science Questions

Why does cutting hair make it stronger?

Chris -   Actually, this is a myth.  There is no evidence that cutting hair, shaving, doing anything like that actually makes hair grow more or adjust its strength or its length.  Hair goes through three phases and its lifetime.  The hair follicle has an anagen phase, when actually grows and makes hair and depending upon what sort of hair, where on the body surface you’re looking, that phase last different lengths of time.

On the head, for example, it lasts for several years, whereas on the face, it might last for weeks and an eyelash, for example, only grows for about three weeks before it goes into the next phase which is called the catagen phase when the hair falls out.  And that’s when the hair follicle stops for a while.  Obviously, you can imagine if your eyelashes grew for three years that would be a bit disadvantageous because you’ll be looking out through under these curtains, won’t you?  So, it’s good that doesn’t happen. Then the third phase is something called the telogen phase, when the follicle rests before it re-starts itself again. 

People often say when a person dies, their hair carries on growing after they die. Or, when you cut the hair it comes back far bushier. Both of those things are down to, in the case of someone dying, the skin dries and shrinks a bit around the hair coming out through the skin surface and this makes the hair look artificially a lot longer; and, when you cut hair, instead of having this tapered thin end, it’s got  a very abrupt, cut off, sharp end, so the hair looks thicker when it comes back.

So, it’s just sort of illusion; it’s not really any fatter.

November 2009