Sleep Loss, Human Memory and Brain Plasticity across the Lifespan

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DESCRIPTION (provided by applicant): Sleep quality, efficiency and continuity are all known to decrease in with age. Co-occurring with these sleep impairments is the cognitive hallmark of aging a progressive deterioration of memory, reducing the ability to acquire and retain facts in later life. Moreover, it is now widely acknowledged that sleep plays a critical role in learning, memory and brain plasticity. However, the possibility that age-related memory decline results, at least in part, from disrupted sleep, remains enigmatic and unexplored. If correct, inadequate sleep would represent an important, but as yet uncharacterized, feature of cognitive aging that is treatable. Combining brain imaging (fMRI) with cognitive measures, we will determine the impact of age-associated sleep loss, and recovery, on the ability to form new human memories. A first series of experiments will determine the relationship between age-related sleep deficits and impaired memory encoding ability in a cohort of medically healthy older adults (age 65-85). These neural and behavioral changes will be compared to young healthy subjects with experimentally manipulated sleep patterns matching those of the older adults; dissociating the effects of age from sleep loss. A second series of experiments will investigate whether daytime naps provide a restorative benefit to memory encoding in older adults, and similarly sleep deprived young adults; overcoming these neural and behavioral effects resulting from sleep loss. Furthermore, these studies will determine whether naps composed of different sleep-stage architectures and of varying durations are more or less recuperative in enhancement learning ability in older and young subjects. Across these programs of research, we will also determine whether high- and low-sleep functioning older adults (i.e. sleep quality and quantity), express differential neural and behavioral memory profiles, as would be predicted by the above hypothesis.Project Narrative: The goal of this proposal is to characterize the relationship between aging, sleep loss and memory deterioration, and further determine the recuperative benefits that a practical intervention (daytime naps) may provide. Understanding how the progressive loss of sleep in aging impacts human memory and brain plasticity has profound clinical, societal and public health implications. Considering that over 70 million people in the U.S. suffer from disordered sleep, which markedly increases in later life, the importance of understanding a link between inadequate sleep and learning difficulties becomes paramount.