Hair follicle Each hair grows at the rate of about half an inch a month. The hair's average life span is 4-5 years before replaced hair can be found on an average head. 90% of these are in their growing phase; this is known as the Anegen phase and is followed by their resting phase (Telogen). After this a new hair starts to grow in the same follicle, pushing out the old one. The period of change between the old one and the new one is called the Cetacean phase.

When there is a delay in this stage of growth, the result as we see it is hair loss. The time to be concerned about hair loss is when we lose more than one hundred hairs a day. It is when those hairs are not replaced that visible thinning occurs. This is called Telogen Effluvium. At this stage there is cause for concern.

Thinning hair can indicate an internal dysfunction. Should this be the case one should seek help. By finding the underlying cause corrective measures can be prescribed to counteract the problem.