Nov. 5, 1999 (Washington) -- The popular notion that the quality of sleep naturally declines with age because the body produces less of the hormone melatonin has many people, particularly the elderly, swallowing pills, sucking on lozenges, and even brewing special tea. But Harvard researchers now say money spent on melatonin supplements may be money thrown away.
A study in this month's American Journal of Medicine shows that healthy older men and women had melatonin levels that were similar to those found in young men. Both study groups stayed for several days at a sleep lab, where they lived under carefully controlled conditions while their melatonin levels were regularly monitored.
Secreted at night by the pineal gland in the brain, melatonin is thought to control sleep cycles, which are frequently disturbed in the elderly. Often described as "the sleep hormone," melatonin is sold without a prescription in a variety of forms. Because it occurs naturally in tiny amounts in barley, rice, turkey, and other foods, it is not regulated by the FDA.
"The common belief was that the pineal [gland] is an aging clock -- that it winds down as we age and heralds our demise. We actually set out to quantify how much melatonin declines and we were shocked to find that it didn't," Charles Czeisler, MD, PhD, one of the study's researchers, tells WebMD.
"The older subjects that we studied did have more sleep disturbances, more fragmented sleep, but that can't be attributed to lower melatonin levels in these subjects." Czeisler is a chief of the section of circadian, neuroendocrine, and sleep disorders in the department of medicine at Harvard Medical School and a senior physician at Brigham and Women's Hospital in Boston.
In light of these findings, Czeisler says, most people don't need melatonin supplements. If they are having problems with sleeping, it is unlikely to be due to a melatonin deficiency. Side effects of medications and other illnesses, such as depression, might be the cause. At a minimum, their melatonin levels should be measured before using supplements, Czeisler says.
"There have been claims that melatonin does everything from curing cancer to improving your sex life," he says. "There are no large-scale studies to show whether melatonin is effective in the treatment of insomnia or whether it is safe. I think it is unwise to buy a compound that hasn't been tested as safe to use, and it is reprehensible that it was released to the public before large scale studies were done."
Czeisler says previous studies that have shown a decline in melatonin in the elderly were flawed because they did not exclude individuals who were taking medications that suppress the hormone and did not control for factors such as sunlight, which affects the level of melatonin in the body.
"This looks like a very good study; they put [people] in a controlled setting, and they were very precise about their posture and the light they were exposed to," says Samuel Durso, MD, a gerontologist and assistant professor at Johns Hopkins University School of Medicine in Baltimore. "I think it is an important study. It is another valuable advance in our understanding of normal physiology of aging."
Durso, who reviewed the study for WebMD, says he also believes melatonin supplements are usually not necessary. "From a therapeutic standpoint, we don't have much good evidence to start with that melatonin is a useful medication for most older people with sleep problems," Durso says.