Physical Activity and Cognition: A Mediating Role of Efficient Sleep

Abstract

Objective Physical activity benefits executive control, but the mechanism through which this benefit occurs is unclear. Sleep is a candidate mechanism given that it improves with exercise and has restorative effects on the prefrontal cortex. The present cross-sectional study examined the mediating role of sleep in the relationship between physical activity and executive control in young and older adults. Participants Young (n = 59) and older (n = 53) community-dwelling adults ages 21–30 and 55–80. Methods Participants wore an accelerometer for one week to assess sleep efficiency, total sleep time, and physical activity, operationalized as metabolic equivalent of task (METs) during time spent awake. Cognition was assessed in the laboratory across multiple measures of executive control, memory recall, and processing speed. Mediation analyses tested the role of sleep efficiency in the cross-sectional relationship between METs and cognitive performance accounting for age, sex, and education. Results METs were significantly associated with performance before, but not after accounting for covariates. METs were associated with sleep efficiency but not total sleep time. Sleep efficiency, but not total sleep time, mediated the relationship between METs and working memory, switching, verbal ability & fluency, and recall. Age group did not moderate the mediating role of sleep efficiency in the relationship between METs and performance. Conclusions Sleep efficiency is one pathway by which physical activity may be associated with executive control across young and older adults.

Analysis of dynamic, bidirectional associations in older adult physical activity and sleep quality

“…This null finding aligns with a recent paper also drawn from this study cohort (Falck et al, ); however, it stands in contrast to the conclusions of a narrative review of observational and experimental studies (Buman & King, ) and to the findings of a meta‐analysis of exercise interventions (Kredlow et al, ). Most relevant, our lack of between‐subject associations differs from a study of younger and older adults, whose sleep and PA were measured via a SenseWear® Armband for 7 days (Wilckens, Erickson, & Wheeler, ). Specifically, this previous study detected a modest association (standardized beta = 0.23) between sleep efficiency and PA, and therefore much larger samples than the current one may be required to reliably detect the association with statistical significance.…”

Mediators of Physical Activity on Neurocognitive Function: A Review at Multiple Levels of Analysis

“…Changes in sleep quality, for example, are linked to both cognition and to PA. However, only one study to date (Wilckens et al, in press) has combined all three variables in a statistical model to test whether sleep can account for the relationship between PA and cognitive performance—the results of this initial study suggest that it can. Similarly, mood is linked both to cognitive performance and PA.…”

“…Both PA and sleep were objectively measured with accelerometry. Wilckens et al (in press) found that PA energy expenditure was positively associated with sleep efficiency, as well as executive functioning and processing speed. Further, sleep efficiency statistically mediated the relationship between PA and several measures of cognitive performance.…”

“…The only study to date that included PA, sleep, and cognition in one model tested the hypothesis that sleep mediates the relationship between PA and executive functioning in 109 young ( n = 59) and older adults (Wilckens et al, in press). Both PA and sleep were objectively measured with accelerometry.…”

Neuroimaging, neuromodulation, and population health: the neuroscience of chronic disease prevention

“…We still have much to learn about the mediators of these effects and moderators of the effects . However, there is clear recognition that the effects of physical activity extend beyond cognitive function and how physical activity‐induced changes to the brain mediate changes in these and other behavioral outcomes is an important avenue for future research.…”