When the old hair is in the telogen phase, activity in the hair follicle is renewed. A new hair in the anagen phase develops and forces the old telogen hair out. This is when hairs are lost and you might notice them in the bath or in your brush or comb.

At any one time, around 90 per cent of most people's hair follicles are in the 'growing' anagen phase and approximately 10 per cent are in the 'resting', or telogen phase. Noticeable hair loss is usually caused by a short anagen phase and a particularly long telogen phase.

In the case of common baldness, male pattern baldness, or what is commonly called hereditary hair loss, genes and hormones cause the miniaturisation or ÔshrinkingÕ of the hair follicles, so the hairs become short and thin so they are barely visible to the naked eye. Eventually the hair follicles shut down completely.

Ref. Androgenetic Alopecia. The Growth and Loss of Hair, The Upjohn Company, 1989.

There are lots of reasons why you might start losing more hair than normal: a medical disorder, prescribed medication, poor nutrition, bad hair care techniques or severe stress such as emotional anxiety, surgery or prolonged illness. You should always consult your doctor if you are concerned about losing your hair.

However, the most common type of hair loss is hereditary hair loss, also known as common baldness, male pattern baldness or androgenetic alopecia.

Apart from heredity, age and testosterone are also believed to cause the onset of hereditary hair loss. It's easy to recognise as your hair starts to become thinner and lighter on the crown and the temples. The hair line begins to recede, but the sides and back stay pretty much the same.