[Sleep and intellectual functioning in the elderly: the role of sleep quality and apnea--literature survey].

In both relatively healthy and in demented elderly people mental abilities and sleep quality decrease in becoming older and nocturnal respiratory disturbance increases. Perhaps there is an association between sleep and cognition. The hypothesis that specific sleep phenomena are necessary to assure an adequate level of cognitive functioning is called the sleep cognition hypothesis. In this article the findings of research in older people are reviewed. 23 research reports were found in which sleep was measured with polysomnography. The findings in relatively healthy older people do not suggest a strong association between sleep and cognition nor a causal effect between a specific cognitive dysfunction and a specific sleep variable. The findings in demented older people concerning sleep and cognition are inconsistent. In relatively healthy older people a significant correlation between nocturnal respiratory disturbance and cognitive functioning was seldom found, whereas in demented older people a clear association was shown. Therefore, in demented older people prudence is necessary in prescribing psychopharmaca because these can enhance the appearance of sleep apneas.