MELATONIN REPLACEMENT THERAPY OF ELDERLY INSOMNIACS

Changes in sleep-wake patterns are among the hallmarks of biological a ging. Previously, we reported that impaired melatonin secretion is ass ociated with sleep disorders in old age. In this study we investigated the effects of melatonin replacement therapy on melatonin-deficient e lderly insomniacs. The study comprised a running-in, no-treatment peri od and four experimental periods. During the second, third and fourth periods, subjects were administered tablets for 7 consecutive days, 2 hours before desired bedtime. The tablets were either 2 mg melatonin a dministered as sustained-release or fast-release formulations, or an i dentical-looking placebo. The fifth period, which concluded the study, was a 2-month period of daily administration of 1 mg sustained-releas e melatonin 2 hours before desired bedtime. During each of these five experimental periods, sleep-wake patterns were monitored by wrist-worn actigraphs. Analysis of the first three 1-week periods revealed that a 1-week treatment with 2 mg sustained-release melatonin was effective for sleep maintenance (i.e. sleep efficiency and activity level) of e lderly insomniacs, while sleep initiation was improved by the fast-rel ease melatonin treatment. Sleep maintenance and initiation were furthe r improved following the 2-month l-mg sustained-release melatonin trea tment, indicating that tolerance had not developed. After cessation of treatment, sleep quality deteriorated. Our findings suggest that for melatonin-deficient elderly insomniacs, melatonin replacement therapy may be beneficial in the initiation and maintenance of sleep.