Sleep and Cognition: A Narrative Review Focused on Older Adults

Nonlinear relationships between sleep duration, mental health, and quality of life: The dangers of less sleep versus more sleep

BACKGROUND

Recent research has found a non-linear relationship between sleep duration and mental health/quality of life. However, it is currently unclear which age group is more affected by sleep duration and what the optimal sleep duration is for each age group. Additionally, the underlying mechanisms of the non-linear relationship between sleep duration and quality of life are not well understood.

METHODS

Therefore, this study utilized questionnaire data from 20,962 participants in the Chinese PBICR-2022 database(Cross-sectional study) and constructed models to analyze the relationship between sleep duration and quality of life.

RESULTS

The results showed that the optimal sleep duration varied among different age groups: approximately 9 h for adolescents, 8 h for early/middle-aged adults, and 7 h for older adults. Compared to other age groups, less or more sleep duration had a greater impact on mental health and quality of life in adolescents. Furthermore, mental health was found to play a significant mediating role between sleep duration and quality of life in both the less sleep group and the more sleep group, but this mediating effect was not significant among the older adults in the less sleep group, whereas the mediating effect of mental health was not significant among the middle-aged adults in the more sleep group.

CONCLUSIONS

This suggests that different age groups have different optimal sleep duration, and age may be an important factor influencing the relationship between sleep duration and mental health/quality of life, with mental health playing a mediating role in the relationship between sleep duration and quality of life.

Association of methyl donor nutrients dietary intake and sleep disorders in the elderly revealed by the intestinal microbiome

Currently, sleep disorders (SD) in the elderly are gaining prominence globally and are becoming a significant public health concern. Methyl donor nutrients (MDNs), such as vitamin B6, vitamin B12, folate, and choline, have been reported to have the potential to improve sleep disorders. Moreover, MDNs help to maintain gut flora homeostasis, and are closely associated with the development of SD. Nevertheless, there has been a lack of comprehensive human studies examining the association between MDNs intake and SD. In our study, we comprehensively evaluated the association between MDNs intake and SD in the elderly and used 16S rRNA gene sequencing to explore the underlying mechanism. We found that the SD group (n = 91) had a lower methyl-donor nutritional quality index (MNQI) and a trend toward lower intake compared to the control group (n = 147). Based on the intestinal microbiome, the beta diversity of the intestinal flora was higher in the high methyl-donor nutritional quality (HQ) group compared to the low methyl-donor nutritional quality (LQ) group, and it was lower in the SD group compared to the control group. This suggests that MDNs may regulate sleep by modulating the abundance distribution of the microbiota. Subsequently, we performed correlation analyses between the relative abundance of the microbiota, MDNs intake, and the Pittsburgh Sleep Quality Index (PSQI), identifying five genera with potential regulatory roles. The KEGG pathway analysis indicated that energy metabolism and one-carbon metabolism might be the pathways through which MDNs modulate sleep. This study offers dietary guidance strategies for managing SD in the elderly and provides insights for targeted microbiota intervention.

Long Objective Sleep Duration is a Marker of Cognitive Impairment in Older Adults: Findings from the Cretan Aging Cohort

 We examined associations between objective sleep duration and cognitive status in older adults initially categorized as cognitively non-impaired (CNI, n = 57) or diagnosed with mild cognitive impairment (MCI, n = 53). On follow-up, 8 years later, all participants underwent neuropsychiatric/neuropsychological evaluation and 7-day 24-h actigraphy. On re-assessment 62.7% of participants were cognitively declined. Patients who developed dementia had significantly longer night total sleep time (TST) than persons with MCI who, in turn, had longer night TST than CNI participants. Objective long sleep duration is a marker of worse cognitive status in elderly with MCI/dementia and this association is very strong in older adults.

Sleep health and aging: Recommendations for promoting healthy sleep among older adults: A National Sleep Foundation report

OBJECTIVES

Sleep is a key health indicator in older adults; however, many older adults may experience less than ideal levels of sleep health. The objective of this report is to summarize the proceedings of the National Sleep Foundation's Sleep Health and Aging Conference.

METHODS

The National Sleep Foundation held a Sleep Health and Aging Conference with sleep scientists and stakeholders in the field of aging. The primary goal of this conference was to identify critical sleep health recommendations for older adults.

RESULTS

Essential recommendations aimed at promoting sleep health in older adults focus on light exposure, physical activity, meal timing, environmental conditions, and sleep schedules. Suggestions for promoting sleep health behavior change in older adults include tailored messaging and community support.

CONCLUSIONS

There are unique challenges and opportunities around promoting sleep health in older adults, efforts toward change should include individual, community, and societal foci.

Detection of Insomnia and Its Relationship with Cognitive Impairment, Depression, and Quality of Life in Older Community-Dwelling Mexicans

Sleep disturbances are one of the most frequent health problems in old age, among which insomnia stands out. It is characterized by difficulty falling asleep, staying asleep, frequent awakenings, or waking up too early and not having restful sleep, which may be a risk factor for cognitive impairment and depression, affecting functionality and quality of life. Insomnia is a very complex multifactorial problem that requires a multi- and interdisciplinary approach. However, it is frequently not diagnosed in older community-dwelling people, increasing the risk of psychological, cognitive, and quality of life alterations. The aim was to detect insomnia and its relationship with cognitive impairment, depression, and quality of life in older community-dwelling Mexicans. An analytical cross-sectional study was carried out in 107 older adults from Mexico City. The following screening instruments were applied: Athens Insomnia Scale, Mini-Mental State Examination, Geriatric Depression Scale, WHO Quality of Life Questionnaire WHOQoL-Bref, Pittsburgh Sleep Quality Inventory. The frequency of insomnia detected was 57% and its relationship with cognitive impairment, depression, and low quality of life was 31% (OR = 2.5, 95% CI, 1.1-6.6. p < 0.05), 41% (OR = 7.3, 95% CI, 2.3-22.9, p < 0.001), and 59% (OR = 2.5, 95% CI, 1.1-5.4, p < 0.05), respectively. Our findings suggest that insomnia is a frequent clinical disorder that is not diagnosed and a significant risk factor for cognitive decline, depression, and poor quality of life.