Melatonin works as sleep aid in small doses, study confirms; but commercially available pills have too much of the supplement

About 0.3 milligrams of melatonin will help a person fall asleep, and it also makes it easier to return to sleep after waking up.

But researchers found that, in larger amounts -- such as those offered in most commercially available pills -- the supplement works for only a few days. After a person's brain has been exposed to too much melatonin, it quickly becomes immune to the substance's restful effects, the study says.

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• Misuse of the hormone had led some to question its efficacy, but the latest work (published in the February issue of Sleep Medicine Reviews) could jump-start interest in the dietary supplement and help more people get a good night's sleep.
• In earlier research, scientists led by Professor Richard Wurtman, principal investigator for the current study, showed that only a small dose of melatonin (about 0.3 milligrams) is necessary for a restful effect.
• The researchers also found, however, that commercially available melatonin pills contain 10 times the effective amount.
• And at that dose, "after a few days it stops working," said Wurtman, director of MIT's Clinical Research Center and the Cecil H. Green Distinguished Professor.
• As a result of these inadvertent overdoses, "many people don't think melatonin works at all," said Wurtman, who is also affiliated with the Department of Brain and Cognitive Sciences.
• This belief, coupled with potentially serious side effects related to high doses such as hypothermia, has earned the hormone a bad reputation in some quarters--"and something that could be very useful to a lot of people isn't," said Wurtman, who said that he and his wife have been taking melatonin every night for about a year now.
• To determine conclusively whether melatonin works or not, the scientists in the current study analyzed 17 peer-reviewed scientific papers about the hormone.
• "A meta-analysis essentially tells 'yes' or 'no'--that a treatment does or does not have a significant effect," Wurtman said.
• Because the FDA defined the hormone as a dietary supplement, however, manufacturers were free to sell it in much higher dosages, "even though we knew they wouldn't work," Wurtman said.
• "People who knew that small doses were best often bought the high-dose pills, then divided them with a knife," Wurtman said.