Napping Associated with Improved Cognitive Functioning in Elderly Chinese Population

by | Feb 8, 2021 | 2021, Brain Health, Cognitive Health, Sleep

Written by Joyce Smith, BS. This study demonstrates that afternoon napping is associated with better cognitive function in the Chinese aging population.

cognitive game for dementiaDementia is increasing due to a longer life expectancy 1 and currently has no effective treatment. Changes in sleep patterns are a component of aging 2 and napping has become a prominent feature in our aging populations 3. Previous studies have shown a higher cognitive benefit in nappers; however, the napping benefit has also been shown to decrease with age 4.

The present study 5 explored a potential association between afternoon napping and cognitive function. Included in the study were 2,214 Chinese elderly (napping group: n=1534; non-napping group: n=680). They all received cognitive evaluations using the Montreal Cognitive Assessment (Beijing version), the Mini-Mental State Examination, and the Neuropsychological Test Battery (Chinese version) 6. Of the total participating subjects, 739 elderly volunteered to take blood lipid tests.

Researchers found significant differences between the nappers and non-nappers. Mid-day napping offered many benefits such as better cognitive function in areas of orientation, language, memory consolidation, enhancement of executive function and strengthening of emotional stability. Unintentional nappers performed poorly in word recall compared to those who napped or who were intentional nappers. The frequency and timing of naps also benefited daytime napping 7. More frequent and longer naps were associated with poorer cognitive functioning, while shorter naps, such as 30 minute naps four times per week, were associated with an 84% decreased risk of Alzheimer’s disease (AD) 8. Of the 739 nappers who took the lipid tests, the 428 nappers scored significantly higher on the MMSE tests than the 311 non-nappers. The nappers also had significantly higher triglycerides (TG) compared to the non-nappers (P=0.001). No significant differences were seen in Cholesterol (CHOL), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) levels between the two groups.

The mechanisms between napping and cognitive function suggest that inflammation functions as a mediator. Inflammatory cytokines such as IL and CRP incite oxidative stress and reactive oxygen species (ROS). Sleep regulates the immune system; however, when deficient, can lead to cognitive impairment and increased mortality. Researchers suggest that napping is a response to inflammation and those with increased inflammation are more frequent nappers 9. While the TG levels in the nappers was higher than in the non nappers, the levels were still considered within the normal range. Researchers point to several studies that found a positive association between napping and cardiovascular disease (CVD) risk factors such as TG. TG have also been linked with increased brain Aß and tau pathology that has shown up 20 years later in cognitive healthy people 10. TG quickly crosses the blood-brain barrier to induce lepton and insulin -receptor resistance, decreasing satiety and cognition 11. A sedentary lifestyle which may encourage napping) may also affect leptin and ghrelin levels that might, in turn, increase appetite and caloric intake, thus contributing to obesity. The research team acknowledges the need to further study the mechanisms involved and plan to do further research on this cohort in the future since this study was not equipped to explore a relationship between napping and dementia.

A cross-sectional design, limited data regarding the nappers, and the potential bias of self-reported napping are limitations of this study.

Source: Cai, Han, Ning Su, Wei Li, Xia Li, Shifu Xiao, and Lin Sun. “Relationship between afternoon napping and cognitive function in the ageing Chinese population.” General Psychiatry 34, no. 1 (2021): e100361.

© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use.

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Posted February 8, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

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