Can a Hormone Imbalance Cause Lighter Periods?

Menstrual Cycle

Menstruation (also known as menstrual periods) is a result of a monthly cycle of hormones and their effects on the uterus. In the first half of the menstrual cycle, levels of the hormone estrogen rise, which causes the uterine lining to become thicker. This is done to prepare the uterus to receive a fertilized egg. If there is no egg fertilization, estrogen levels taper off, which causes the uterus to shed its lining (also known as sloughing). This sloughing causes menstrual bleeding, which, according to the National Institutes of Health (NIH), lasts for four days, although the duration varies from woman to woman.

Hormone Levels and Light Periods

Menstrual bleeding is typically lighter at the beginning of puberty and at the end of reproductive life (also known as premenopause, which occurs before complete menopause). This is because the ovaries are not consistently (i.e. every month) producing a mature egg. The maturation of an ovarian follicle is what ultimately produces a viable egg and is also what causes the increase in estrogen. Consequently, a failure to ovulate (also known as anovulation) can lead to a lighter period as the uterine lining does not receive sufficient stimulation from estrogen to thicken.

Other Causes

Most women fail to ovulate once or twice every six months, which can result in a lighter than normal period. This is not generally a cause for concern, although a gynecologist may need to be consulted if a woman is having difficulty in becoming pregnant or becomes concerned about irregular periods. Sometimes irregular and lighter periods are caused by a condition known as polycystic ovarian syndrome. Another cause of light periods (also known as hypomenorrhea) is Asherman's syndrome, which is a result of damage to the endometrium, usually from surgery, resulting in small tears or adhesions to the lining of the uterus.