A dose of the natural hormone melatonin brings on sleep quickly without addiction, researchers say, and could help victims of insomnia or jet lag.
Melatonin is secreted by the pineal gland in the brain. Earlier studies showed that levels of the hormone in an adult were about 10 times higher at night and that light and darkness had an effect on the secretions.
This suggests that melatonin helps people develop a natural rhythm of sleep and wakefulness _ a role that Dr. Richard Wurtman, professor of neuroscience, said was proved by his studies at the Massachusetts Institute of Technology.
He said studies also have shown that older people, who often suffer from insomnia, have far less melatonin in their bodies at night than young people. This suggests the lack of melatonin may lead to sleep difficulties among the old.
In the MIT studies, 20 young male volunteers were given pills of melatonin or placebos and then placed in a dark room at midday and told to close their eyes for 30 minutes.
"Our volunteers fall asleep in five or six minutes on melatonin, while those on placebo take about 15 minutes or longer," Wurtman said. He predicts a formal application for that use of the hormone within a year.
However, he warned the wrong doses of melatonin could cause mood-altering side-effects. Melatonin is sold in some health food stores, but the sale of the hormone is not controlled and its purity and strength often are uncertain.
"People should not self-medicate with melatonin," he said, because there is some risk in taking the hormone without supervision.
A report on the study was published Tuesday in the Proceedings of the National Academy of Sciences.