Melatonin, one of the body’s naturally produced hormones linked to sleep, has been promoted as the latest darling in treating sleep problems, especially jet lag. But while the hormone, available as a dietary supplement, may have benefits for short term sleep trouble, the jury is still out on it’s long term benefits for chronic sleep disorders.

"Regrettably, there are no good large scale studies that can tell us whether it has benefits or not," says Harvey Moldofsky, MD, director of the University of Toronto Center for Sleep and Chronobiology and an expert on fibromyalgia-related sleep problems. "For fibromyalgia (use), it's mostly anecdotal evidence, " he says.

What’s more, he points out that little – if anything – is known about possible long-term risks of using melatonin. In fact, a recent University of Michigan study found that post-menopausal women with fibromyalgia actually had elevated levels of melatonin in their bodies. Researchers don’t know how taking supplements would affect the body when it already makes too much melatonin.