by Barbara L. Minton

(NaturalNews) Melatonin is nature’s sleeping pill. It is secreted by the light sensitive pineal gland which regulates our biological clock and synchronizes our hormonal-immune network. Our level of melatonin rises with darkness and falls with light. According to Dr. Uzzi Reiss, in his book Natural Hormone Balance, a healthy pineal gland produces 2.5 milligrams of melatonin every twenty-four hours.

Melatonin plays a central role in the natural aging processes of the body. When pineal production begins to diminish, at around age 40, the decline sets off changes in the operation of the body’s cells. The physiology of the cell shifts from repair and rejuvenation to aging and degeneration.

Recent studies are now showing that as our levels of melatonin sink, our chances for breast cancer rise. Many women with breast cancer have lower levels of melatonin than those without the disease. Laboratory experiments indicate that lower levels of melatonin stimulate growth of breast cancer cells. Adding melatonin to these cells inhibits their growth.

Breast cancer and melatonin: studies and results

According to a study at the Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain, published in Molecular and Cellular Biochemistry, Oct. 2005, melatonin increases the survival time of animals with untreated mammary tumors.

Researchers concluded that melatonin is beneficial during advanced breast cancer. It increases survival time, perhaps by improving the homeostatic and neuroendocrine equilibrium which is imbalanced during advanced breast cancer.

As published in the International Journal of Cancer, January, 2006, researchers at the Department of Physiology and Pharmacology, School of Medicine, University of Cantabria, Santander, Spain, found that melatonin inhibits the growth of induced mammary tumors by decreasing the local biosynthesis of estrogens through the modulation of aromatase activity. They note that melatonin inhibits the growth of breast cancer cells by interacting with estrogen-responsive pathways, effectively behaving as an anti-estrogenic hormone. They had previously described that melatonin reduces aromatase expression and activity in human breast cancer cells, thus modulating local estrogen biosynthesis.

Researchers conclude that melatonin could exert its antitumoral effects on hormone dependent mammary tumors by inhibiting the aromatase activity of the tumoral tissue.

And in the April, 2007 edition of Oncology Report, this same research team at the University of Cantabria, Santander, Spain, reports the effects of MT1 melatonin receptor over-expression on the aromatase-suppressive effect of melatonin in human breast cancer cells. They note that a major mechanism through which melatonin reduces the development of breast cancer is based on its anti-estrogenic actions by interfering at different levels with the estrogen-signaling pathways.

Transfection of the MT1 melatonin receptor in the breast cancer cells significantly decreased aromatase activity, and MT1-transfected cells showed a level of aromatase activity that was 50% of vector-transfected cells. The proliferation of estrogen-sensitive cells in an estradiol-free media but in the presence of testosterone (an indirect measure of aromatase activity) was strongly inhibited by melatonin in those cells over-expressing the MT1 receptor. This inhibitory effect of melatonin on cell growth was higher on MT1 transfected cells than in vector transfected cells. In MT1-transfected cells, aromatase activity was inhibited by melatonin. The same concentrations of melatonin did not significantly influence the aromatase activity of the vector-transfected cells. MT1 melatonin receptor transfection induced a 55% inhibition of aromatase expression in comparison to vector-transfected cells. Additionally, in MT1-transfected cells, melatonin treatment inhibited aromatase expression and induced a higher down-regulation of aromatase expression than in vector-transfected cells.

The researchers concluded that their findings point to the importance of the MT1 melatonin receptor in mediating the oncostatic action of melatonin in human breast cancer cells, and confirm the MT1 melatonin receptor as a major mediator in the melatonin signaling pathway in breast cancer.

If you choose to rely on your own production of melatonin, be aware that production of melatonin rises from bedtime until the middle of the night, and then slowly declines throughout the rest of the night. This production is dependent on you sleeping in a dark room. If you get up during the night and turn on the light or open the refrigerator door, your melatonin production will abruptly stop.