Perimenopause, extreme weight gain or loss, stress, medications, an endocrine disorder and metabolic syndrome can all create fluctuations in the menstrual cycle that can cause menstruation to occur earlier than usual, according to CNN. Any change in a menstrual cycle that lasts longer than three weeks should be evaluated by a gynecologist, according to CNN.
Perimenopause, a transitional period that occurs up to five years before menopause, can cause both the lengthening and shortening of the menstrual cycle, sleep problems and hot flashes and can often be controlled with hormone therapy, according to CNN.
Stress, a leading cause of changes in the menstrual cycle, produces the hormone cortisol, which has a direct impact on the estrogen and progesterone produced by the body, greatly impacting the length of the menstrual cycle, according to She Knows.
Any medications that work on the central nervous system, such as antidepressants, can also cause changes in the menstrual cycle, according to CNN. Endocrine disorders, such as thyroid disease and polycystic ovary disease, and metabolic syndrome, which is a group of risk factors correlated with heart disease and diabetes, including high blood pressure, high blood sugar and low levels of HDL cholesterol, can also account for fluctuations in the menstrual cycle, according to CNN.