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Study: Diet Supplement Helps People Sleep


NPR's Richard Knox reports.

RICHARD KNOX: First, let's get straight on how not to take melatonin, according to the new study.

CHARLES CZEISLER: Melatonin taken at the typical time most people take melatonin, which is before nighttime sleep, did not improve their sleep. And that's probably why melatonin has a mixed reputation.

KNOX: To determine when a melatonin pill does work to improve sleep, Czeisler and colleagues locked 36 healthy young volunteers, one at a time, in a windowless, soundproof room, away from all contact with the outside world, for 21 days. Then they used light and darkness cycles to really screw up their circadian clocks.

CZEISLER: We shifted the person's timing of when they slept four hours earlier. It would be like traveling from Anchorage to New York and making that kind of a shift every day, traveling further and further eastward and going around and round the globe.

KNOX: This was necessary to separate melatonin's role as a re-setter of people's biological clocks from its function as a sort of reverse alarm clock that signals time to sleep. When the study subjects took even a tiny dose of melatonin during the time when their natural melatonin levels were low, that is, when their bodies thought it was daytime, they slept better.

CZEISLER: If we increase blood levels of melatonin during the daytime, when the body doesn't release melatonin, we do improve the ability of participants to sleep during the daytime.

KNOX: Their sleep efficiency improved. That's the amount of time they actually slept while they were in bed.

CZEISLER: Our study shows that if they were taking melatonin when they were attempting to sleep during the daylight hours, they'd get an extra half an hour of sleep.

KNOX: Dr. Thomas Roth says a half hour more sleep is a big deal.

THOMAS ROTH: It's very important to understand, sleep loss is cumulative.

KNOX: Roth is a leading sleep researcher at Henry Ford Hospital in Detroit. He says people generally run up a sleep deficit during the workweek.

ROTH: Most of us, because we lose about a half hour of sleep a night, sleep longer on weekends.

KNOX: But for those who want to act on these findings, there's a problem. There's no way to tell whether the bottles of melatonin you buy in the drugstore or health food store actually contain any melatonin.

ROTH: By and large, the products in health food stores are not governed by anybody. There's no agency which sort of defines what's in there.

KNOX: Richard Knox, NPR News, Boston. Transcript provided by NPR, Copyright NPR.

Morning Edition
Since he joined NPR in 2000, Knox has covered a broad range of issues and events in public health, medicine, and science. His reports can be heard on NPR's Morning Edition, All Things Considered, Weekend Edition, Talk of the Nation, and newscasts.