A popular dietary supplement, melatonin used to be promoted simply as a way to treat insomnia and prevent jet lag. No more.
Now it’s touted to treat or prevent everything from fatigue, anxiety, headaches, and depression to dementia, tinnitus, irritable bowel syndrome, and skin damage from the sun. Not to mention heart disease and cancer, as well as menopausal symptoms and all the other signs of aging. There are even melatonin-based drinks like iChill and Dream Water that are supposed to help you relax.
Anything that’s marketed as a cure-all should set off warning bells.
The darkness hormone
Melatonin is a hormone produced by the brain’s pineal gland; it is also found in some edible plants. It has been called the “darkness hormone” (in contrast to vitamin D, the “sunshine hormone”) because it is secreted at night; exposure to light suppresses it.
Since melatonin affects circadian rhythms—that is, our internal body clock and sleep/wake cycle—and promotes drowsiness, it has long been used as a sleeping aid. In fact, one prescription sleeping pill, ramelteon (Rozerem), works by mimicking the effects of melatonin in the body.
Recent research on isolated cells and lab animals has shown that melatonin has antioxidant, anti-inflammatory, immunological, and potential anti-cancer effects. Such findings don’t mean, of course, that it has these effects to any significant degree in people.
Melatonin production tends to decline as people age. Some researchers have suggested that various age-related changes and conditions (such as declining immunity, cognitive losses, and sleep disturbances) are due at least in part to this drop in melatonin.
Marketers often use the notion that declining melatonin levels need to be replaced as a selling point for supplements—similar to the way estrogen “replacement” therapy was once promoted as a way to prevent chronic disease and keep women feeling young. But many compounds produced by the body decline with age. And even if you replaced them, that wouldn’t necessarily help keep you healthy or prevent the effects of aging—and it wouldn’t necessarily be without risk.