Association between REM sleep regulation and working memory functioning measured in healthy elderly adults

Abstract

Aging implies changes in cognition and memory functioning, some of the components decline with an important inter-individual difference. Working memory, combining executive functions and memory abilities, is sensitive to the aging process (Nyberg et al., 2012). Further, cognitive processes are sensitive to the time of the day. The interplay between sleep-wake regulating mechanisms is indeed not only underlining sleep and wakefulness regulation but influences also attentiveness and alertness, hence induces 24-hour modulation of cognitive performance (Maire et al., 2013). To add, sleep is important to protect cognitive abilities and sleep disturbances can lead to cognitive decline or impairment. Furthermore, aging leads to significant changes in sleep behavior and sleep structure (Song et al., 2015). One sleep component that is presumed to decline with age and implicated in brain plasticity, is the quantity, density, and latency of rapid eye movement (REM) sleep (Rodriguez et al., 2014). REM sleep is assumed to have a role in protecting cognitive functioning and enhancing different cognitive abilities, but its exact influence on cognitive functioning is mostly unclear (Lafortune et al., 2014). In this master thesis, we examined the association between REM sleep and the working memory N-back measurement in elderly adults. Applying a REM depriving constant routine protocol, the REM percentage during baseline measurement as well as the REM rebound (percentage of REM sleep during baseline sleep opportunity difference with percentage during recovery sleep) were investigated in their association with the N-back D-prime baseline score as well as the difference between day and night time sessions. No statistically significant associations were found for these principal hypotheses. For future research, further investigation into the association between REM sleep, but also SWS, and their rebound with working memory measurements, taking more variables in the sleep structure and their interaction into account will be necessary.