Menopause is caused by the cessation of ovarian activity and a dramatic fall in circulating estrogen levels. Decreasing estrogen levels prompt your pituitary to produce more follicle stimulating hormone and luteinizing hormone in a futile physiologic effort to stimulate your ovaries. Hot flashes, vaginal dryness, insomnia, mood changes, weight gain and other menopausal problems result from these widespread hormonal changes. In an effort to relieve the troubling symptoms related to menopause, many women turn to alternative remedies, such as melatonin.
Osteoporosis
Estrogen helps preserve bone strength by stimulating the activity of bone-building cells called osteoblasts. The loss of estrogens following menopause is believed to play a major role in the genesis of osteoporosis in older women. The primary justification for using hormone replacement therapy in postmenopausal women is to preserve bone mass and prevent osteoporosis. A June 2010 review in "Journal of Osteoporosis" suggests that melatonin helps prevent bone loss and promotes bone formation by stimulating osteoblasts. Optimal melatonin doses needed to affect bone integrity are unclear, but at least one animal study used 10 mg per kg of body weight daily, which would translate to nearly 700 mg for a 150 lb. adult.
Insomnia
Melatonin is secreted by the pineal gland at the base of your brain. Your pineal gland synthesizes more melatonin during darkness than during daytime hours, which accounts for its pivotal role in establishing circadian rhythms and normal sleep-wake cycles. As people age, they produce less melatonin, and many elderly individuals suffer from sleep disturbances as a result. An August 1995 study published in "The Lancet" demonstrated that 2 mg of controlled-release melatonin administered at night to elderly subjects for three weeks significantly improved their sleep quality.
Breast Cancer
According to a June 2003 "Endocrine-Related Cancer" review, one of melatonin's roles is to inhibit the secretion of pituitary and gonadal hormones, which stimulate estrogen receptors in breast tissue. A postmenopausal drop in melatonin production permits increased stimulation of these receptors and ostensibly accounts for a higher incidence of breast cancer among melatonin-deficient women. The study's authors noted that melatonin also exerts a direct suppressive effect on breast cancer cells when it is present in "physiologic concentrations," which are the levels produced by a young, healthy pineal gland. However, melatonin has not been shown to prevent or cure breast cancer, and optimal postmenopausal doses have not been determined.
Considerations
Melatonin exerts physiologic actions that extend beyond its popular use as a sleep aid. Menopause brings a reduction in melatonin levels due to a decrease in pineal activity. It is unclear if doses commonly used to improve sleep -- 2 to 3 mg before bedtime -- will confer any other health benefits. Clinical studies have failed to show any benefit from melatonin for the treatment of menopausal hot flashes. Check with your doctor to see if melatonin is appropriate for you.
References
- "Journal of Osteoporosis"; Scientific Basis for the Potential Use of Melatonin in Bone Diseases: Osteoporosis and Adolescent Idiopathic Scoliosis; E.J. Sánchez-Barceló, et al.; June 2010
- "Surgical and Radiologic Anatomy"; Evaluation of the Relationship between Inducible Nitric Oxide Synthase (iNOS) Activity and Effects of Melatonin in Experimental Osteoporosis in the Rat; G. Oktem, et al.; December 2005
- "The Lancet"; Improvement of Sleep Quality in Elderly People by Controlled-Release Melatonin; D. Garfinkel, et al.; August 1995
- "Endocrine-Related Cancer"; Melatonin and Mammary Cancer: A Short Review; E.J. Sánchez-Barceló, et al.; June 2003
- "Maturitas"; Soy Isoflavones and Melatonin for the Relief of Climacteric Symtpoms: A Multicenter, Double-Blind, Randomized Study; G. Secreto, et al.; January 2004
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