Blind women don’t get breast cancer — or at least their risk for breast cancer is substantially less than sighted women.  And the reason has to do with two things: light and a hormone called melatonin.

Most people who have heard of melatonin know it as a supplement that can help with sleep (more on that in a moment). And that it’s great for jet lag. But the melatonin story is alot more interesting — and complicated — than its ability to serve as a natural cure for insomnia. Melatonin may have a role in protecting you against cancer.  It also supports the immune system and is one of the most powerful antioxidants we know of.

Melatonin is produced by the pineal gland, a gland in the brain that helps regulate circadian rhythm.  It’s actually made along the same metabolic assembly line as serotonin. Both start out as the amino acid tryptophan, which then gets converted into 5-HTP and then to serotonin. Two more steps along the pathway and you’ve got melatonin.

Melatonin is stimulated by darkness, and turned off by light. One reason scientists believe that the risk for breast cancer is lower in blind women is that they have less exposure to light and presumably more melatonin. We don’t know for sure if that’s true, but we do know that in one study¹, scientists grafted human breast cancer tumors on to rats and then exposed them to blood taken from women during darkness and after exposure to light. The blood taken during darkness slowed the growth of the cancers by a whopping 80 percent; meanwhile the blood taken after light exposure accelerated it.

Then there’s melatonin’s most famous use — helping regulate sleep. Melatonin helps set the brain’s internal clock.  It’s terrific for jet lag and for anytime that your sleep cycle is artificially disrupted.  A good deal of research shows that melatonin is useful for insomnia, though there’s some debate about which is best — regular melatonin or the time-released kind. The immediate release kind might be more effective for decreasing the time it takes to fall asleep, but the time release kind might be better for improving sleep quality and maintenance.

If all these benefits weren’t enough, melatonin is one of the most potent antioxidants known.  It’s believed to be many times more effective at protecting cell membranes than vitamin E, and more effective than glutathione (one of the body’s antioxidant stars) at neutralizing one of the most dangerous of the free radicals — hydroxyl radicals. And on top of it, melatonin supports immune function in a variety of ways.

Melatonin may interact with certain medications, especially benzodiazepines, antidepressants, and CNS (central nervous system) depressors like alcohol. Don’t take it and drive.

If you’re going to try melatonin for a better night’s sleep, start with 3 mg right before bedtime, though you may find 6-10 mg more effective.

1. Blask, DE, Daugchy RT, et al  Neuro Endocrinol Lett 2002 Jul;23 Suppl 2: 52-6.

[Ed. Note: Dr. Bowden is a nationally known expert on weight loss, nutrition and health. He's a board certified nutrition specialist with a Master's degree in psychology. Dr. Bowden is also a life coach, motivational speaker, former personal trainer and author of the award-winning book, Living the Low Carb Life. For more information, click here.]

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