Melatonin treatment for age-related insomnia

Older people typically exhibit poor sleep efficiency and reduced nocturnal plasma melatonin levels. The daytime administration of oral melatonin to yo unger people, in doses that raise their plasma melatonin levels to the noct urnal range, can accelerate sleep onset. We examined the ability of similar , physiological doses to restore nighttime melatonin levels and sleep effic iency in insomniac subjects over 50 yr old. In a double-blind, placebo-cont rolled study, subjects who slept normally (n = 15) or exhibited actigraphic ally confirmed decreases in sleep efficiency (n = 15) received, in randomiz ed order, a placebo and three melatonin doses (0.1, 0.3, and 3.0 mg) orally 30 min before bedtime for a week. Treatments were separated by 1-wk washou t periods. Sleep data were obtained by polysomnography on the last three ni ghts of each treatment period. The physiologic melatonin dose (0.3 mg) rest ored sleep efficiency (P < 0.0001), acting principally in the midthird of t he night; it also elevated plasma melatonin levels (P < 0.0008) to normal T he pharmacologic dose (3.0 mg), like the lowest dose (0.1 mg), also improve d sleep; however, it induced hypothermia and caused plasma melatonin to rem ain elevated into the daylight hours. Although control subjects, like insom niacs, had low melatonin levels, their sleep was unaffected by any melatoni n dose.