Hair thinning, i.e. a gradual reduction in the diameter of individual hairs, can be caused by a number of factors, the most common being ‘androgenic thinning’. With androgenic thinning, the growth (anagen) phase of your hair cycle becomes shorter and shorter, and the hair also grows back progressively finer. Hair thinning can occur on its own or alongside increased hair shedding. 

Androgenic thinning is related, as the name implies, to androgens (male hormones) and is genetically determined. What may (or may not!) suprise you is that both men and women have androgens. However, the levels are higher in men.

Androgenic hair thinning is usually more common, and noticeable, in men than in women due to the higher levels of male hormones. The pattern of loss can also be different. However, genetic hair thinning is not only related to how high your male hormone levels are, but also to how sensitive your follicles are to them. For instance, even sub-normal amounts of androgens in women can cause hair thinning if they have high follicle sensitivity.