The depth and continuity of sleep changes with age because there is a lower percentage of sleep spent in the deepest stages of non-REM sleep, there are more frequent arousals and awakenings during the sleep episode, and the inability to sustain sleep for the desired duration frequently occurs.

As if fitful sleep wasn't bad enough, the elderly are deluged with misinformation inspired by marketing efforts that offer a "cure-all" for the problem. Too often they are told that a melatonin deficiency is the cause of their distress. Melatonin is a putative sleep-related hormone. Studies of exogenous melatonin administration have shown that melatonin can facilitate sleep onset at certain times of day. But now, a new study asserts that it is the body's inner clock -- involved with the production of melatonin -- which may be the obstacle to a good nights sleep. This challenges the marketers notions that the problem is a deficiency of the hormone itself.

Background
One of the most prominent changes in sleep that accompanies aging is a shift (to an hour earlier) in the timing of a nightly sleep episode. In addition to sleep timing, the rhythms of core body temperature and plasma cortisol are also known to occur at an earlier hour in older people. Age-related changes in the amplitude of circadian rhythms of hormone secretion and core body temperature have also been reported.

There may be a causal link between the age-related changes in hormone secretion and core body temperature with changes in sleep. Conversely, a single mechanism may underlie these changes. Given that the circadian timing system regulates the timing and internal organization of sleep
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Contact: Donna Krupa
dkrupa1@aol.com
703-527-7357
American Physiological Society
12-Feb-2002