Q: I’ve heard that melatonin can help people sleep, and that it also has major health benefits, especially in regard to cancer. Can you explain? And do you have any related tips for improving my sleep?

Melatonin, a hormone released naturally in your brain, may not only help you sleep but may also help prevent diseases, including cancer. Research shows that sleep is essential for optimal health, but sleep that allows you to release adequate levels of melatonin is even more important.

Melatonin is produced from the amino acid L-tryptophan within your pineal gland, which is under the control of your retina, the light-sensitive part of your eye. During darkness, your pineal gland produces peak levels of melatonin – not only helping you fall asleep, but also acting as a powerful antioxidant in your body. If light shines on your eyes during the night, however, your pineal gland produces less melatonin and your sleep patterns can be disrupted, potentially altering your circadian rhythms (the daily temporal cycles of your biological processes). This is important, because research shows an association between low melatonin production, heart disease, breast cancer, and prostate cancer. To get a good night’s rest, make your bedroom as dark as you can – remove all electric lights, including even your alarm clock – and wear an eye mask if possible.

Another way to protect your healthy melatonin production is to avoid shift work. An article published in Occupational Medicine in 2010 points out that “shift work is associated with an increased risk of major disease (heart disease and cancer) and this may also, at least in part, be attributed to frequent circadian desynchrony.” (Desynchrony is a state in which circadian rhythms are thrown off.)

According to a 2009 article in the journal Integrative Cancer Therapies, melatonin “suppresses the development and growth of breast cancer by regulation of growth factors, regulation of gene expression, – inhibition of tumor cell invasion and metastasis – ” This means that melatonin can play a key role in preventing breast cancer. In a recent article in the Scandinavian Journal of Work, Environment, and Health, researchers explore possible mechanisms between shift work and cancer, suggesting that melatonin suppression through exposure to light at night could contribute to breast cancer in women and prostate cancer in men.

For women who have been diagnosed with breast cancer that is responsive to estrogen, melatonin may play a role in preventing a recurrence. Melatonin has an anti-cancer effect on estrogen-positive breast cancer cells, according to the Journal of Biological Chemistry in 2004.

In addition to increasing your body’s production of melatonin with lifestyle changes, you can take melatonin as a dietary supplement, available over-the-counter at drugstores and health food stores. The recommended dose is a .5 to 3 milligram tablet taken sublingually (under your tongue) right before bedtime.

Dr. Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu, as well as author of the new #1 best-selling book Natural Choices for Women’s Health, published by Random House. You can reach her and read her past columns at www.drsteelsmith.com This column is for information only. Consult your health provider for medical advice.