We all lose a certain amount of hair every day - anywhere from 50 to 100 to 125 hairs. It is true that hair loss occurs when we lose these hairs do not grow back, or when the amount of hair losing each day that exceeds normal range.
Hair loss can occur as a result of medications such as chemotherapy treatments or anticoagulants, which can damage the telogen hairs, or stop cell division that produces natural hair then weakened that is susceptible to breakage. High doses of vitamin A can also lead to hair loss as well. The most common type of hair loss, however, is where more and more hair follicles go into what is called the resting phase (telogen phase) in the growth cycle of hair.
Overall, the hair grows continuously from the scalp, but moves away from the scalp in 3 phases. Hair is not uniform across a stage. Different parts of the scalp will be at different stages, so that at any time, you must have hair follicles in 3 phases. In general, most (90%) hair will be in Phase Anaga, 10 to 14% of hair is in the telogen phase, and only 1 to 2% of hair at the stage catogen.
The first phase is the phase of Anaga, which is the growth phase. This may take between 2 and 8 years. In the shorter Anaga phase limit the time your hair can grow. Ciliated cells at the root divide rapidly, which will lengthen the shaft of the hair.
In the next phase, the catagen phase, outside the root hair follicle shrinks and attaches to the root of hair. The hair growth stops here. This phase lasts from 1 to 2 weeks.
telogen phase is the phase of rest. This lasts from 5 to 6 weeks in normal hair. Hair does not grow at this stage, but remains firmly rooted in the scalp, as long as the follicle remains in a resting phase below it. New growth begins at the end of the phase of sleep, and this is where the natural hair shedding is going to happen, since the new growth pushes the old hair.
In male pattern baldness, more hairs enter the telogen phase. The effects of this are increased shedding of hair. Hair gradually becomes thinner and shorter, and in the end, hair follicles off.