Cardiorespiratory Fitness May Protect Memory for Poorer Sleepers.

Tara Kuhn,Jennifer Heisz

doi:10.3389/fpsyg.2022.793875

Abstract

ObjectivesPhysical activity has been shown to protect executive functions against the deleterious effects of poorer sleep among older adults (OA); however, it is unknown whether memory is protected too, and if this relationship differs by age. The present study investigated the relationship between cardiorespiratory fitness, sleep, and memory in both older and young adults (YA).MethodsThis observational study recruited 26 OA (70.7 ± 2.8 years) and 35 YA (21.0 ± 3.1 years). Participants completed the Rockport 1-mile walk test to evaluate cardiorespiratory fitness. Participants wore an actigraph for 1 week to measure habitual sleep and returned for a second visit to perform the memory tests. The interaction between cardiorespiratory fitness and sleep to predict memory was assessed separately in OA and YA.ResultsIn OA, cardiorespiratory fitness significantly moderated the relationship between memory and sleep quality, specifically number of nighttime awakenings, sleep efficiency, and wake after sleep onset. Further analyses reveal that a high number of nighttime awakenings and low sleep efficiency significantly predicted worse memory performance in the low fit OA, but high fit OA. Notably, every nighttime awakening was associated with a nearly 4% decrease in memory in low fit OA, but not high fit OA. Wake after sleep onset did not significantly predict memory in either fitness group. No interaction was found when looking at sleep duration or self-report sleep quality in OA and no significant interactions were observed between fitness, sleep, and memory in YA.ConclusionOverall, the results suggest that cardiorespiratory fitness may act as a protective buffer for memory in OA with poor sleep quality. These same was not true for YA suggesting that the protective effects of cardiorespiratory fitness on sleep-related memory impairments may be age specific.

Highlights

IntroductionNearly 1 in 3 adults fail to achieve these recommendations (Chaput et al, 2017)
High-interference memory scores were removed if participants failed to understand the task, as indicated by failing to press all three keys (OA, n = 1)
Among low fit older adults (OA), highinterference memory performance was directly related to their sleep quality, such that every nighttime awakening was associated with a ∼4% decrease in high-interference memory; likewise, every 1% decrease in sleep efficiency was associated with a ∼4% decrease in high-interference memory

Summary

Introduction

Nearly 1 in 3 adults fail to achieve these recommendations (Chaput et al, 2017). Many OA may be in bed for the recommended amount of time but struggle to fall asleep and stay asleep (Chaput et al, 2017). Such poor sleep quality is related to poor cognition. Compared to younger adults (YA), OA sleep less, have more difficulty initiating and maintaining sleep, and spend less time in slow wave sleep (SWS) – sleep’s deepest and most restorative stage (Ohayon et al, 2004; Moraes et al, 2014; Mander et al, 2017)

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Conclusion