<P> The anagen phase is known as the growth phase . This is the phase where the hair physically grows approximately 1 cm per month . It begins in the papilla and can last from two to six years . The span at which the hair remains in this stage of growth is determined by genetics . The longer the hair stays in the anagen phase, the longer it will grow . During this phase, the cells in the papilla divide to produce new hair fibers, and the follicle buries itself into the dermal layer of the skin to nourish the strand . About 85% - 90% of the hairs on one's head are in the anagen phase at any given time . </P> <P> The catagen phase, also known as the transitional phase, allows the follicle to, in a sense, renew itself . During this time, which lasts about two weeks, the hair follicle shrinks due to disintegration and the papilla detaches and "rests," cutting the hair strand off from its nourishing blood supply . Signals sent out by the body (that only selectively affect 1 percent of all hair of one's body at any given time) determine when the anagen phase ends and the catagen phase begins . The first sign of catagen is the cessation of melanin production in the hair bulb and apoptosis of follicular melanocytes . Ultimately, the follicle is 1 / 6 its original length, causing the hair shaft to be pushed upward . While hair is not growing during this phase, the length of the terminal fibers increase when the follicle pushes them upward . </P> <P> During the telogen or resting phase (also known as shedding phase) the follicle remains dormant for one to four months . Ten to fifteen percent of the hairs on one's head are in this phase of growth at any given time . In this phase the epidermal cells lining the follicle channel continue to grow as normal and may accumulate around the base of the hair, temporarily anchoring it in place and preserving the hair for its natural purpose without taxing the body's resources needed during the growth phase . </P> <P> At some point, the follicle will begin to grow again, softening the anchor point of the shaft initially . The hair base will break free from the root and the hair will be shed . Within two weeks the new hair shaft will begin to emerge once the telogen phase is complete . The process results in normal hair loss known as shedding . </P>

How long is the telogen phase of hair growth