To protect skin from any of light effects which body produces melanin will become dark and more darker leads to pigmentation.
In case of women at pregnancies, and in case of thyroids, PCOD issues, this problem occurs.
Pigmentation disorders affects melanin. Melasma butterfly type of dark brown pigmentation on the face is common in women, mostly after or at menopause, due to hormones disorder melonocysts effects badly produces excesses of melanin or less melanin.
It is due to loss of pigmentation, which makes the skin lose its natural colour, leads pale patches.
It is caused by a very low amount of melanin being produced by the cells and it makes the skin lighter than normal. Apart from primary pigmentation can also result from injuries to the skin such as burns, ulcers, chemical exposure, or skin infection.
Hyper pigmentation is a result of the production of a very high amounts of melanin by the melanocysts, making the skin darker than normal. It can also be caused by other pigmented substances, drugs or sun light exposure.