BERLIN, GERMANY. Whether or not melatonin improves sleep pattern is a subject of controversy. A team of Dutch and German researchers now weigh in with a new study that clearly shows that melatonin increases the duration of rapid-eye-movement (REM) sleep and helps alleviate disorders associated with disturbed REM sleep. The double-blind, placebo-controlled, parallel design study involved 5 women and 9 men with an average age of 50 years who suffered from reduced REM sleep duration and neuropsychiatric sleep disorders such as narcolepsy (daytime sleepiness), restless leg syndrome, insomnia, and periodic limb movement disorder. The participants took placebo or a 3-mg melatonin capsule as closely as possible to their normal bedtime, but always between the hours of 2200 and 2400 (10 p.m. to midnight) every night for 4 weeks and were then assigned to the opposite treatment after a 1-week washout period.
The researchers found that patients in the melatonin group increased the duration of their REM sleep by
about 20% and also showed a significant drop in minimum rectal temperature during the night. Eleven out
of 14 patients reported clear improvements in their symptoms during melatonin treatment. Nine reported
reduced daytime fatigue, 8 reported a stronger sense of feeling refreshed after awakening in the morning,
and 8 reported increased sleepiness in the evening. None of the participants reported any side effects or
changes in frequency, content, intensity or quality of their dreams. Of particular interest was the finding that
the beneficial effect of melatonin lasted will beyond the time period in which the supplement was actually
taken. In other words, once the circadian pacemaker is reset it remains this way for weeks or months after
melatonin supplementation is discontinued. The researchers point out that it is crucial to keep the timing of
melatonin administration constant. They also warn that melatonin may have undesirable long-term effects
and should not be used for extended periods of time, except under the supervision of a physician.