How Hair GrowsHair, like every growing thing, has it’s own ‘cycle of life’. At any given time approximately 90 percent of the hair on your head will be in a ‘growing’ phase and 10 percent will be in a ‘resting’ phase. The growth phase lasts somewhere between two and six years while the resting phase is estimated to last anywhere from 2 – 3 months. It is after this cycle of growing and resting that a hair will die and be replaced by another new hair from the same follicle. This process begins at about the age of 10 weeks and will continue for most of your adult life – all things being equal. It is natural, therefore, to lose a certain amount of hair every day due to this natural cycle of hair growth.
The amount of hair on your head varies depending on the natural color of your hair. You will start out life with approx. 1000 or so follicles per square centimeter. This will progressively drop as you get older to something like 300 follicles per square centimeter as you approach the ages of 35-50. The good news is that things slow down a bit from there. A natural blonde will have, on average, about 50% more hair than a natural redhead and about 35% more than a natural brunette - and that hair will grow typically about one centimeter a month during early to middle adulthood. As a person ages their rate of hair growth slows and therefore the rate of replenishment slows resulting in thinner hair.
There are three distinct types of hair that grows on a human body, but it is two in particular that we are concerned with regarding hair loss – Vellus and Terminal hair (the third kind is called Lanugo hair and is the hair that grows on an unborn baby).
Vellus hairs are hairs that are most commonly associated with newborn babies – short hairs, only a centimetre or two long, which are almost transparent as they contain little or no pigment. The reason for the transparent look is that the follicles that produce them do not have oil glands (these oil glands are referred to as sebaceous glands), and thus are limited to producing this particular kind of hair.