Menstrual Cycle

• A normal menstrual cycle has an average length of 21 to 35 days, with 28 days being an average. Actual menstrual bleeding takes part in the first quarter of your menstrual cycle, lasting about three to five days.
  
  

Abnormal Uterine Bleeding

• Since a normal menstrual cycle at its earliest begins every 21 days, anything that starts before is considered dysfunctional uterine bleeding. Dysfunctional uterine bleeding is any abnormal bleeding not caused by an outside factor.
  
  

Identification

• A menstrual period that frequently lasts less than 21 days is called polymenorrhea. In polymenorrhea, the actual menstrual bleeding time is normal, lasting between three and five days.
  
  

Psychological Causes

• Emotional stress, anxiety, fatigue and being overworked all can contribute to polymenorrhea. These conditions can cause your hormonal balance to fluctuate, resulting in early menstrual periods. Once the stress subsides, the periods might return to normal.
  
  

Physical Causes

• Conditions such as polycystic ovarian syndrome and perimenopause cause fluctuations in the hormones estrogen and progesterone that are responsible for menstrual cycle regulation. You might have to take medication to regulate the hormones in order for periods to return to normal.