Reasons for an abnormal period that's lighter than usual can range from stress, excessive exercise or birth control pill use to more serious problems, such as polycystic ovary syndrome, premature ovary failure or anemia, according to the Cleveland Clinic. If there is a possibility of pregnancy, a light period or spotting could also be caused by implantation bleeding as a fertilized egg attaches to the uterine lining.
According to the Cleveland Clinic, it's important to visit a gynecologist for any irregular change in the period after regular menstruation has been established. Keep an accurate record of the length of periods, amount of flow and any associated symptoms to help the gynecologist compile a medical history and diagnosis. Expect a pelvic exam, Pap smear and additional testing, such as blood work, laparoscopy, pelvic ultrasound or pregnancy testing during the visit to diagnose the reason for light menstruation. Minimize the likelihood of abnormal light periods in the future by maintaining a healthy diet, exercise routine and sleep schedule. Avoid excessive or prolonged exercise, and do not lose a lot of weight in a short period of time with dramatic calorie limitations to prevent changes in the menstrual cycle. Practice stress reduction meditation or other techniques to lower stress levels and regulate the menstrual cycle naturally.