One may notice large amount of hair on the pillow or brush just after recovery from illness or after giving birth. Sometimes it may also happen due to stress in life. Polycystic ovary syndrome is the common cause for hormonal imbalance, also known as PCOS, which results in the development of cysts on the ovaries of a woman. This may also include hair loss, apart from various other signs. Hormonal imbalance can also be due to taking birth control pills and the woman having this kind of imbalance can tend to have hair loss.