Worse Subjective Cognitive Performance Linked to Poor Sleep Quality, Infrequent Exercise

Miranda G. Chappel-Farley, BS

A recent study’s findings suggested that a higher number of cognitive complaints in patients was associated with less frequent exercise and worse sleep quality. In addition, data suggested that the relationship between the frequency of exercise and cognitive complaints was mediated by sleep, which was driven by symptoms of potential obstructive sleep apnea (OSA). 

Investigators, led by lead author Miranda G. Chappel-Farley, BS, PhD candidate, department of neurobiology and behavior, the University of California–Irvine, included a total of 2106 adults between the age of 18 and 89 years enrolled in a recruitment registry, then analyzing questionnaire data. A higher Cognitive Function Instrument (CFI) score was found to be associated with Medical Outcomes Sleep Scale subscales (MOS-SS) scores and factor scores, as well as exercise frequency.

A higher rate of cognitive complaints was associated with higher Sleep Somnolence, Sleep Disturbance, Sleep Problems Index I, Sleep Problems Index II, and factor scores, while fewer cognitive complaints were associated with higher Sleep adequacy. Sleep duration was also associated with number of cognitive complaints, as investigators found that patients who slept the shortest amount each night (between 4-5 hours) and the longest amount (between 9-10 hours) had significantly more complaints (μ long = 0.527 [P = .010]; μ short = 0.545 [P <.001]), when compared to mid-range sleepers (between 6-8 hours; μ mid = 0.422).

When evaluating the association between exercise and cognitive complaints, investigators found that more frequent exercise was associated with a lower number of complaints (ß = –0.002; P = .022; robust standard error [SE] = .0009; t = –2.46).

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More frequent exercise was also associated with higher sleep adequacy (ß = 0.350; P_adj <.001; robust SE = 0.072; t = 4.84); less daytime sleepiness (ß = –2.51; P_adj = .001; robust SE = 0.059; t = –4.27), as well as fewer sleep problems (Index I: ß = –0.214; P_adj <.001; robust SE = 0.050; t = –4.52). Also found to be associated with more frequent exercise was lower obstructive sleep apnea (ß = –0.004; P_adj <.001; robust SE = 0.0007; t = –5.27), lower insomnia (ß = –0.002; P_adj = .044; robust SE = 0.0009; t = 2.55), nightmare disturbance (ß = −0.005; P_adj <0.001; robust SE = 0.0009; t = −5.14), and Daytime Impact Factor Scores (β = −0.005; P_adj <.001; robust SE = 0.0008; t = −5.670). There was no significant association between exercise frequency and sleep duration (P = .718)

Investigators also noted that the association between exercise and cognitive complaints was mediated by MOS-SS subscales and factor scores, not including Sleep Disturbance and the Insomnia Factor score. Symptoms suggestive of OSA were also negatively associated with engagement in exercise, sleep quality, daytime sleepiness, as well as cognitive performance. 

“We present a novel framework wherein the relationship between exercise frequency and subjective cognitive function is, in part, due to the relationship between frequent exercise and sleep,” Chappel-Farley, et al wrote. “Using self-report data from a large sample of community-dwelling adults, we found that worse subjective sleep quality and less frequent exercise were associated with more cognitive complaints. We further determined that the relationship between exercise frequency and cognitive complaints was mediated by sleep, most strongly by self-reported symptoms suggestive of OSA.”

“These findings have important public health implications and may suggest that untreated OSA may negatively impact exercise engagement and subjective cognitive performance. Future prospective studies using objective measures of sleep, exercise, and cognitive function are needed to confirm these mediation effects, particularly in patients with OSA,” Chappel-Farley et al added.

The study was limited in that causality was unable to be inferred due to the study being based on self-reported, cross-sectional data, and investigators could not adjust for self-report bias, making results difficult to generalize. The influence of alcohol and caffeine intake were also excluded from analyses, as they were not part of the recruitment registry. Several participants also reported a previous cancer diagnosis (24.6%), but due to registry limitations, investigators were unable to determine diagnoses and/or treatment status, which may impact sleep, exercise, and cognitive performance. 

Investigators noted the need for longitudinal data to confirm the relationships identified in the study and the need for additional studies in the future to incorporate objective data, namely overnight polysomnography, and electroencephalography. 

REFERENCE

Chappel-Farley MG, Mander BA, Neikrug AB, et al. Symptoms of obstructive sleep apnea are associated with less frequent exercise and worse subjective cognitive function across adulthood. SLEEP. Published online October 4, 2021. doi:10.1093/sleep/zsab240