The effect of sleep fragmentation on sleep and performance in younger and older subjects.

Groups of 12 normal 55-70-year-old and young adult subjects had their sleep experimentally disturbed at a rate of approximately 14 times per hour to determine the residual effects of moderate sleep disturbance and to determine any differential impact as a function of age. Normal age-related changes in sleep were seen on baseline and recovery nights. In the second night of sleep disturbance, the older subjects had a smaller increase in total awakenings than young adults. Older subjects had a slower increase in auditory arousal threshold as sleep disturbance progressed. The older subjects also tended to have less performance deterioration on morning testing than did young adults, and this difference was significant for numbers of correctly completed addition problems. These evidences led to the conclusion that, while both age groups were sensitive to moderate sleep disturbance, the older individuals appeared somewhat less sensitive than the young adults.