We need a good night’s sleep to remain cognitively ‘with it’.

In addition to the classic question “why do we sleep?” we might add “How does sleep impact cognitive functioning. Both questions have been the focus of research for decades. For example, 30 years ago a number of researchers linked sleep and the consolidation of memories, a line of study that continues to this day.

 Kristine Yaffe of the University of California, San Francisco, and her colleagues published an article in the Aug. 10 Journal of the American Medical Association showed that older women whose sleep is disrupted (because of sleep apnea) are much more likely to develop dementia. In another, better controlled study, using rats as subjects, Asya Rolls of Stanford and her colleagues reported online July 25 in the Proceedings of the National Academy of Sciences that disrupted sleep severely impacts memory for recent events. The study design included the use of sophisticated neuroscience methods for disrupting sleep (a light sensitive protein inserted into selected brain cells and fiber-optic cables implanted in the brain activating those cells and briefly waking the animals. The animals that slept in fits and starts demonstrated robust impairments in memory. The results are interpreted on the basis of the role of (continuous) sleep in memory consolidation.