During normal hair growth stages each hair follicle follows a specific life cycle. The first is a long period of growth. The second phase is short period of ‘rest’. During this rest period your hair is still attached to the hair follicle, but it is not growing. After the resting phase the hair is shed and a newer hair begins to grow, starting a new hair growth cycle.
Anagen Phase – Hair grows at about 1/2″ per month for 2 to 3 years. 80 to 90% of all hair on the scalp is in the stage.
Catagen Phase – This is the 2nd phase of hair growth. In this phase the bulb of the hair follicle detaches from the blood supply and growing is slowed.
Telogen Phase – Finally, the stage of zero growth, the hair is at rest. The hair is shed after a few months and new hair will grow.
If any of these stages become abnormal then your hair will not grow properly.