Daily sleep reports and circadian rest-activity cycles of elderly community residents with insomnia

Sleep patterns were investigated in 29 insomniacs and 22 controls selected from a large sample of elderly residents of an urban community. According to sleep logs kept for a mean of 14.7 days, insomniacs took longer to fall asleep and stayed awake longer when they woke at night. In 14 insomniacs and 8 controls, wrist movements were monitored with a portable instrument. A circadian rhythm of motor activity was found in both groups, with some notable differences. Insomniacs were more active during periods of bedrest, and their mean daily rest-activity pattern--representing mean activity at equivalent times of day--was flatter. The mean level of activity over the entire experiment was similar in both groups. Insomnia in many elderly persons is thus associated with diffusion of activity over the 24-hr day, leaving bedrest periods only partially filled by rest or sleep.