Temporal constraints on sleep and cognition

Maintaining temporal coordination of multiple oscillators increases the fitness of an organism and provides it with the most efficient response to the environment. As such, the appropriate temporal framework of sleep and wake states, orchestrated through circadian rhythmicity, putatively represents a key factor that modulates an individual’s cognitive trajectory. The temporal organization of sleep and wakefulness evolves throughout lifespan that can be altered as the brain ages. Several lines of evidence support a relationship between disrupted sleep and/or circadian rhythmicity and cognitive performance in those suffering from neurodegenerative diseases, but also among healthy older subjects. While sleep is increasingly considered as protective for healthy ageing, circadian aspects of the temporal organization of sleep remain largely unexplored in this branch of research. During my presentation, I will first review evidence for an impact of both circadian and homeostatic sleep regulation on cognition and its underlying cerebral correlates. I will than introduce the hypothesis that the temporal organization of rest-activity rhythms putatively acts as a protective and modifiable factor for cognitive and brain aging. The topic is of relevance since both, cognitive decline and inadequately timed sleep represent dominant determinants of the health span of an aging population and easy implementable intervention programs are urgently needed.