Circadian rhythms and psychiatric disorders in the elderly.

This article reviews changes in circadian rhythms that have been reported to occur in the elderly psychiatric population. Data relating to circadian changes in normal aging are included where relevant. Information was obtained from: (1) a computerized MEDLINE search from 1975 to May 1996; (2) a review of bibliographies of papers obtained through the computerized search; and (3) texts on chronobiology. We could not locate any information relating to circadian rhythms and mania, anxiety, or paranoid disorders in old age. Disruption to the sleep/wake cycle, temperature, melatonin, and motor activity rhythms have been reported in dementia and depression, and disruption to some neuroendocrine and cardiovascular rhythms are reported in dementia. Disruption to circadian rhythmicity has implications for the management of dementia patients: for example, the sleep/wake and behavioral disturbances, and for the long-term management of mood disorders. A number of circadian markers have not been studied and several patient groups have received no research attention to date.