Forget what the school nurse told you back in fifth grade—hardly anyone has a menstrual cycle that lasts exactly 28 days. There’s wide variation among women, says Marcelle Pick, an ob-gyn nurse practitioner and cofounder of the Yarmouth, Maine-based Women to Women holistic health program. What’s important is when your normal shifts. Even then, an occasional irregular cycle is nothing to worry about, she says.

But hormonal shifts that produce significant and frequent cycle disruption are signals to pay closer attention. “Healthy menstruation is an indication of a healthy state of mind and a healthy body,” says Bobby Clennell, author of The Woman’s Yoga Book (Rodmell, 2007).

Balance is key, says Alicia Stanton, MD, an integrative physician and coauthor of Hormone Harmony (Healthy Life Library, 2009). At the beginning of your cycle, estrogen helps the egg develop; the ovulated egg then forms the corpus luteum cyst, which makes progesterone. Estrogen helps thicken the uterine lining; progesterone stops growth and stabilizes the lining for embryo implantation, she explains. If you don’t get pregnant, progesterone declines sharply and the lining sloughs off during the next few days. Or at least that’s the way it’s supposed to work. When it doesn’t, a few common causes are prime suspects.

Symptom: Heavy, frequent bleeding.

If your period suddenly starts coming more frequently for a few cycles in a row (say, every 20 days instead of your usual 28), or lasting longer (say, six days instead of three), or brings abnormally heavy bleeding that prevents you from doing your usual activities, it’s often a sign that your body is not producing enough progesterone to balance estrogen, Stanton says. So the lining keeps thickening until it breaks off and repeatedly sheds in fragmented pieces, she explains.

Common culprits

  1. Polycystic ovarian syndrome (PCOS). About 1 in 15 women has PCOS, a hormone-imbalance condition associated with insulin resistance. In PCOS, egg follicles form but they don’t release, leading to insufficient progesterone and sometimes heavy bleeding, Stanton explains. Even if you don’t have PCOS or insulin resistance, it’s important to shed excess weight. “Women who have a lot of belly fat have a lot of estrogen,” she says.
  2. Perimenopause. The earliest menopause signs—including hormone imbalance and failure to ovulate—can start in your late 30s and lead to heavy bleeding, says Pick. Chronic stress worsens the imbalance, because the adrenal glands direct cortisol production toward stress response instead of using cortisol as a building block for progesterone.
  3. A health condition or infection. Structural problems, such as endometriosis, uterine polyps and fibroids; low thyroid function; prolonged antibiotic use; and even infections like chlamydia and gonorrhea can lead to irregular, heavier periods.

Restore balance

  1. Reduce body fat through diet and exercise.
  2. Manage stress. Try meditation or a gratitude journal. “You can’t feel gratitude and stress at the same time,” Stanton says.
  3. Consider vitex or black cohosh supplements. Or, if you prefer an Eastern approach, consult an acupuncturist for treatment, which may include traditional Chinese “blood-moving” herbs.
  4. Apply warm castor oil. To stabilize flow, moisten a flannel pack (available at natural products stores; a folded, old T-shirt will do in a pinch) with warmed castor oil; place oil-side down on your lower abdomen with a hot-water bottle on top; cover with a towel. Do this daily for an hour (but not during your period) for a few months; then gradually reduce frequency to twice a month. Your period might initially become heavier or more painful, but that’s just stagnation clearing from the uterus, says Claudia Welch, author of Balance Your Hormones, Balance Your Life (Da Capo, 2011).
  5. Try yoga. Before your period, do supported versions of standing poses like triangle and half-moon to create space and ease in the pelvic region, suggests Clennell. During your period, restorative yoga postures such as reclining bound-ankle pose can restore energy and relax abdominal organs. The rest of the month, practice seated postures, such as seated wide- angle pose, to tone reproductive organs and relieve abdominal tension; and inversions, such as standing forward bends and supported head or shoulder stand, to stabilize hormonal output and regulate flow.