Written by Marcia Egles, MD. In a test with 36 adults, those taking melatonin had sleep efficiencies by 6 or 7% more than the control group.
A study from the Divisions of Sleep Medicine at Brigham and Women’s Hospital and Harvard Medical School reports that melatonin supplements may significantly improve a person’s ability to sleep during daytime hours. Most people sleep at night, but this study has relevance particularly for night-shift or rotating shift workers, for jet lagged travelers, and for astronauts. During night time hours when the body produces its own melatonin, the study found that, in these normal subjects under sleep laboratory conditions, giving supplemental melatonin offered no additional effect. (1)
In humans, melatonin is a hormone produced by the pineal gland, a pea-sized structure in the middle of the brain. Primarily, it is released when the body is in darkness. Its production is inhibited by exposure of the eye’s retina to light. Melatonin functions in the body’s biological clock or circadian rhythms, helping the brain to determine night and day. (2)
Twenty-one men and fifteen women, 18-30 years of age, in excellent health with no history of sleep problems, participated in this 27-day study. Starting three weeks prior to admission, they were required to refrain from drugs of any kind including caffeine, alcohol and nicotine. The sleep laboratory suites were described as private, windowless, and sound isolated and free of time clues with controlled artificial lighting. The subjects wore special sleep-monitoring head gear and temperature sensors. Through the use of special 12-foot long tubing, hourly blood samples could be painlessly obtained without entering the subject’s room.
The subjects were divided into three groups; each group receiving placebo or 0.3mg or 5.0 mg pharmaceutical grade melatonin. The capsules were given thirty minutes prior to each scheduled sleep time. Neither the researchers nor the subjects were allowed to know to which group a subject belonged during this double-blinded study. During the study, participants were made to stay awake for 13 hours 20 minutes and then allowed to sleep for the next 6 hour 40 minute period. As each of their “days” was only 20 hours instead of the usual 24 hour period, they were forced to gradually shift their sleep time into the daytime, and then back into nighttime as each 20 hour “day” passed.
The purpose of this shortened-day pattern was to test melatonin administration across a full range of circadian phases. Such parameters as the time required to fall asleep and the amount of time spent sleeping were recorded. Hourly levels of melatonin levels in the blood were measured.
The researchers found that sleep efficiency, that is, the percentage of time that the subjects spent asleep during the 6 hour 40 minute sleep opportunity, was significantly higher in the melatonin groups during times when the body was not producing its own melatonin. During those times, participants taking 0.3mg and 5.0 mg melatonin had sleep efficiencies of 84 and 83 per cent respectively. In comparison, those who received placebo had a sleep efficiency of 77 percent, (1) which is about 30 minutes less sleep. For those whose real life requires daytime sleep, melatonin supplements might be a valuable aid for getting more sleep.
Source: Wyatt, James K., Derk-Jan Dijk, Angela Ritz-De Cecco, Joseph M. Ronda, and Charles A. Czeisler. “Sleep-facilitating effect of exogenous melatonin in healthy young men and women is circadian-phase dependent.” Sleep 29, no. 5 (2006): 609-618.
Posted July 23, 2008.
References:
- Wyatt JK et al. Sleep-Facilitating Effect of Exogenous Melatonin in Healthy Young Men and Women Is Circadian-Phase Dependent. Sleep, May 2006; 29: 609-618.
- Wikipedia – pineal gland.
