Circadian abnormalities in older adults

This study examined the circadian phase adjustment of symptomatic elders ag es 60-79 years in comparison with that of young, healthy adults ages 20-40 years. Seventy-two elders with complaints of insomnia or depression, and 30 young, healthy adults were assessed for 5-7 days at home. Sleep and illumi nation were recorded with Actillume wrist monitors and sleep diaries. Urine was collected over two 24-hr periods and assayed for 6-sulphatoxymelatonin (6-smt). The volunteers were then observed continuously for 5 nights and 4 days in the laboratory. In the laboratory, sleep periods were fixed at 8 h r with polysomnographic assessment of sleep, apnea-hypopnea, and nocturnal myoclonus. Circadian dispersion, defined as the mean variation of 6-smt acr ophase from the median age-specific acrophase, was significantly greater in the older vs. young adults. Likewise, circadian malsynchronization, define d as the absolute number of hours (advance or delay) between the 6-smt acro phase and the middle of the sleep period, was significantly greater in the older vs. young volunteers. For the older volunteers, multiple regressions were calculated associating sleep with potential correlates of sleep distur bance. Nocturnal myoclonus and circadian malsynchronization were more stron gly associated with sleep impairment than other factors (e.g., sleep apnea, depression). These observations suggest that circadian malsynchronization might be a common and significant cause of disturbed sleep among adults ove r age 60.