TORONTO — Melatonin supplements have been hailed as a godsend by some weary shift workers, insomniacs and those with jet lag, but a new study out of the University of Alberta says they don't actually help much at all.

"It has no benefit...That's the bottom line," Dr. Terry Klassen, the lead investigator of the study, said Thursday in a telephone interview from Calgary. "That's why there's such a great need in health care to have such a rigorous and extensive look at these types of issues."

Melatonin is a hormone found in the brain, and can be reproduced synthetically or isolated from an animal. It's commonly used as a sleep aid.

But the new study, released by the U.S. Department of Health and Human Services, concluded that the supplements ultimately have little benefit.

Although melatonin was found to help some insomniacs fall asleep more quickly, it did so with limited success.

Some patients who had "secondary sleep disorders" - including those with anxiety disorders and neurological conditions - had longer sleeps due to melatonin but the number was not enough to be considered clinically significant.

The study -- which pulled together data from more than 50 studies - also raised questions about the long-term effects of melatonin.

"We honestly don't know in humans if they took it for a year whether there may be some as-yet-undiscovered side effect or adverse event on those patients," said Klassen. "It's an unknown question."

In the mid-1990s, Canadian health food stores were instructed to halt sales of melatonin because it was considered a drug. About a year ago, however, the government re-classified it as a natural health product, meaning it was once again available.

Gerry Harrington of NDMAC, a Canadian association of non-prescription drug manufacturers, says that melatonin research is ongoing and is currently being evaluated by Health Canada.

"There is science to support melatonin having an impact on the regulation of sleep cycles," he said.

While Harrington did not have current numbers on melatonin use, he said that data from five years ago showed that two to three per cent of the population had tried the supplements at least once.

At Noah's Natural Foods in Toronto, supplements manager Mercy De Leon said customers have positive things to say about melatonin.

"We have a lot of good feedback from customers," she said. "It is popular for people who want to get more sleep."

Klassen isn't surprised that people are still looking to melatonin for a good night's rest.

"(It's) the hype, (the) personal anecdotes," he said. "In the face of unbridled enthusiasm, we have to apply the cold rational face of science to see what is the truth."

He says it's possible that some people think melatonin works because of a "mind over matter" effect while others may see an improvement in their sleeping patterns as a result of something other than the supplements.

The $230,000 US study was funded by the National Center for Complementary and Alternative Medicine, part of the Department of Health and Human Services National Institutes of Health.