Melatonin, a natural hormone known for its sleep-inducing properties, is released from the pineal gland in the brain at night. Recent research, however, has uncovered additional sites where melatonin may be synthesized and secreted. Its role as a health-promoting agent has become well established, given the evidence to support its role in the treatment of insomnia, regulation of the immune system and importance within a cancer context, including the metastatic state.
Insomnia and Hypothermia
Researchers reported in the Journal of Endocrinology and Metabolism in 2001 that administering various doses of melatonin, from 0.1 mg to 3 mg, to elderly subjects with insomnia yielded improved sleep efficiency, defined as a percentage of the total actual sleep time during the entire sleep period. While all subjects experienced a drop in body temperature, it was noted that supraphysiologic doses -- doses higher than the recommended dose of 0.3 mg of melatonin -- induced significant hypothermia in some study subjects.
Regulation of the Immune System
Spanish researchers have made the landmark discovery that melatonin secretion may not only take place in the pineal gland within the brain but also via immune cells. Published in the Journal of the Federation of American Societies for Experimental Biology in 2004, in the study immune cells were isolated and found to contain the enzymes necessary to convert tryptophan into melatonin, namely serotonin-N-acetyltransferase (NAT) and hydroxyndole-O-methyltransferase (HIOMT). This is suggestive of melatonin's role in immunology. More specifically, the researchers discovered that melatonin was positively associated with IL-2 secretion. IL-2 is a cytokine involved in T-cell differentiation and ultimately plays a role in host defense.
Role in Cancer
The idea that IL-2 therapy can be a therapeutic agent in cancer treatment was explored by researchers at the National Institutes of Health in Science in 2002. High-doses of IL-2 therapy promoted the rapid growth in vivo of T cells responsive to a melanocyte differentiation antigen thought to be involved in metastatic melanoma. What was ultimately found was a destruction of the metastatic tumors.
Additionally, researchers published in Pharmacological Research in 2003 a study showing that melatonin administration in rats yielded a significant reduction in uterine estrogen receptors over control rats, linking melatonin to a possible role in hormone-dependent conditions, including menstruation and menopause. This finding is also relevant to estrogen-receptor-mediated cancers, including breast and ovarian.
Health Disclaimer
While generally considered safe, melatonin's use as a treatment for a variety of conditions, including insomnia and cancer, is still being studied. Consult with your physician regarding the best medical approach for your condition. Analysis in this article is presented as informative and not as medical authority.
References
- Zhdanova, I.V. et al. Journal of Endocrinology and Metabolism. Melatonin Treatement for Age-Related Insomnia. 2004; 86; 4727-4730.
- Carrillo-Vico, A. et al. The Journal of the Federation of American Societies for Experimental Biology. Evidence of melatonin synthesis by human lymphocytes and its physiological significance: possible role as intracrine, autocrine and/or paracrine substance. 18; 537-539.
- Dudley, M.E. et al. Science. Cancer Regression and Autoimmunity in Patients After Clonal Repopulation with Antitumor Lymphocytes. 298; 850-854.
- Abd-Allah, Adel R.A., et al. Pharmacological Research. Effect of melatonin on estrogen and progesterone receptors in relation to uterine contraction in rats. 47; 349-354.
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