Associations of accelerometer-based sleep duration and self-reported sleep difficulties with cognitive function in late mid-life: the Finnish Retirement and Aging Study

Finnish Retirement and Aging Study: a prospective cohort study

PURPOSE

The Finnish Retirement and Aging (FIREA) Study was set up to study changes in health behavioural and cardiometabolic risk factors across retirement transition, and to examine the long-term consequences of work and retirement on health and functioning with advancing age.

PARTICIPANTS

Public sector workers whose estimated statutory retirement date was in 2014-2019 were invited to participate by sending them a questionnaire 18 months prior to their estimated retirement date. In the first phase of the FIREA Study, participants were followed up with annual surveys, accelerometer and clinical measurements during retirement transition into post-retirement years. The FIREA survey cohort includes 6783 participants, of which 908 belong also to the activity substudy and 290 to the clinical substudy.

FINDINGS TO DATE

Collected data include survey measures about health, lifestyle factors, psychosocial distress, work-related factors as well as retirement intentions. Accelerometer and GPS devices are used to measure 24-hour movement behaviours. Clinical examination includes blood and hair sample, measurements of anthropometry, cardiovascular function, physical fitness, physical and cognitive function. Our results suggest that in general retirement transition seems to have beneficial influence on health behaviours as well as on physical and mental health, but there are large individual differences, and certain behaviours such as sedentariness tend to increase especially among those retiring from manual occupations.

FUTURE PLANS

The second phase of the FIREA Study will be conducted during 2023-2025, when participants are 70 years old. The FIREA Study welcomes research collaboration proposals that fall within the general aims of the project.

Sleep Duration and Executive Function in Adults

PURPOSE OF REVIEW

To review the literature examining the relationship between sleep and cognition, specifically examining the sub-domain of executive function. We explore the impact of sleep deprivation and the important question of how much sleep is required for optimal cognitive performance. We consider how other sleep metrics, such as sleep quality, may be a more meaningful measure of sleep. We then discuss the putative mechanisms between sleep and cognition followed by their contribution to developing dementia.

RECENT FINDINGS

Sleep duration and executive function display a quadratic relationship. This suggests an optimal amount of sleep is required for daily cognitive processes. Poor sleep efficiency and sleep fragmentation are linked with poorer executive function and increased risk of dementia during follow-up. Sleep quality may therefore be more important than absolute duration. Biological mechanisms which may underpin the relationship between sleep and cognition include brain structural and functional changes as well as disruption of the glymphatic system. Sleep is an important modifiable lifestyle factor to improve daily cognition and, possibly, reduce the risk of developing dementia. The impact of optimal sleep duration and sleep quality may have important implications for every ageing individual.

Daytime Napping and Cognitive Health in Older Adults: A Systematic Review

BACKGROUND

Daytime napping may improve cognitive function in older adults. However, the association can be complicated by specific features of napping and the older adult's health. This systematic review aims to synthesize the current literature on napping and cognition in older adults and provide recommendations for future research and daytime sleep practice in older adults.

METHODS

Systematic searches for relative research published between January 1995 and October 2022 were conducted at PubMed, MEDLINE, PsycINFO, and Google Scholar using keywords individually and in multiple combinations. Manual searches were performed to identify additional studies. All included studies were critically appraised by 2 authors.

RESULTS

Thirty-five studies, including 23 observational and 12 intervention studies, were reviewed. Findings from observational studies suggest a possible inverted U-shaped association between napping duration and cognitive function: short and moderate duration of naps benefited cognitive health in older adults compared with both non-napping and long or extended napping. Findings from intervention studies suggest one session of afternoon napping might improve psychomotor function and working memory, although with some inconsistency. The effect of multiple nap sessions on cognition was inconclusive due to a limited number of studies.

CONCLUSION

More rigorous research studies are needed to investigate what causes different patterns of daytime napping, the associations between these distinct patterns and cognitive function, and to determine whether interventions targeting napping patterns can improve cognition in older adults. In addition, future research needs to comprehensively assess daytime napping using a combination of measures such as sleep diary and actigraphy.

The association of previous night's sleep duration with cognitive function among older adults: a pooled analysis of three Finnish cohorts

STUDY OBJECTIVES

Sleep duration has been shown to associate with cognitive function, but little is known about the short-term effect of sleep duration on the previous night. This study examines how usual sleep duration and previous night's sleep duration are associated with cognitive function in older adults.

METHODS

The study population consisted of 2949 adults aged 59-92 years (mean 72.6, SD 5.7) derived from three Finnish cohorts. Participants' self-reported usual sleep duration was categorized into short (< 7 h, 19%), mid-range (7- < 9 h, 64%), and long (≥ 9 h, 17%). Self-reported sleep duration on the night prior to cognitive testing was categorized into shorter (59%), same (35%), and longer (5.9%) than usual sleep duration. Computerized Cambridge Neuropsychological Test Automated Battery (CANTAB®) was used to assess: (1) learning and memory, (2) working memory, (3) information processing, and (4) reaction time.

RESULTS

Participants with self-reported long, but not short, usual sleep duration had poorer learning and memory (p = .004), information processing (p = .003), and reaction time (p = .006) when compared to those with mid-range sleep duration. Those who slept more than usually the night prior to cognitive testing had poorer information processing (p = .019) than those sleeping the same as usually, while sleeping less than usually was not associated with cognitive function.

CONCLUSIONS

This study suggests that while long sleep duration was associated with worse cognitive function, sleeping more than usually the night prior to cognitive testing was only associated with information processing, and sleeping less than usually is not associated with cognitive function.

Does work-related and commuting physical activity predict changes in physical activity and sedentary behavior during the transition to retirement? GPS and accelerometer study

We examined how GPS and accelerometer measured work-related and commuting physical activity contribute to changes in physical activity and sedentary behavior during the retirement transition in the Finnish Retirement and Aging study (n = 118). Lower work-related activity was associated with a decrease in sedentary time and an increase in light physical activity during retirement. Conversely, higher work-related activity was associated with an increase in sedentary time and a decrease in light physical activity, except among those active workers who also were active commuters. Thus, both work-related and commuting physical activity predict changes in physical activity and sedentary behavior when retiring.

Association of sleep with cognitive function during retirement transition: the Whitehall II study

STUDY OBJECTIVES

Sleep duration and difficulties have been shown to associate with cognitive function. This study examined how changes in sleep and in cognitive function are associated during retirement transition.

METHODS

The study population consisted of 2980 Whitehall II study participants, who retired during the follow-up, whose sleep was queried, and cognitive function measured (inductive reasoning and verbal memory) before and after retirement (follow-up 16 years). Using the last information on sleep before and the first after retirement, participants were categorized into constantly without (59%), increasing (13%), decreasing (11%), and constantly with (18%) sleep difficulties; and constantly short (26%), increasing (19%), decreasing (8.5%), and constantly mid-range (47%) sleep duration. Change in cognitive function during retirement transition was examined by sleep change groups using linear regression analyses with generalized estimating equations.

RESULTS

More pronounced decline in inductive reasoning during retirement transition was observed among participants with increasing sleep difficulties (-1.96, 95% CI -2.52 to -1.41) compared to those constantly without sleep difficulties (-1.25, 95% CI -1.52 to -0.98) and constantly with sleep difficulties (-1.26, 95% CI -1.75 to -0.92). Decreasing sleep difficulties (-0.64, 95% CI -0.86 to -0.43) were associated with a more pronounced decline in verbal memory when compared to constantly without sleep difficulties (-0.42, 95% CI -0.52 to -0.32) in post-retirement period. No statistically significant differences across sleep duration groups in cognitive function were observed.

CONCLUSIONS

Increasing and decreasing sleep difficulties may be associated with accelerated decline in cognitive function during retirement transition and post-retirement.

Independent associations between sleep duration, gamma gap, and cognitive function among older adults: Results from the NHANES 2013-2014

This study examined whether gamma gap mediated the association between sleep and cognitive function. Data from NHANES 2013-2014 were used. Three tests were used to measure cognitive function. Sleep was measured by three single questions. Gamma gap was calculated by subtracting albumin from total protein. Participants were 1392 older adults (53.2% females). Approximately 12% reported being told having sleep disorder, 1/3 reported having trouble sleeping, 25.9% had short sleep, and 12.5% had long sleep. Sleep disorders and sleep quality were not associated with cognitive function. Long sleep duration was an independent risk factor of reduced cognitive function on immediate recall, delayed recall, and executive function. Elevated gamma gap was also an independent risk factor of lower cognitive function. In a representative sample of older adults in the US, gamma gap and sleep duration were independent predictors of cognitive function. This study highlights the need for sleep assessment among older adults.

Association of short sleep with risk of periodontal disease: A meta-analysis and Mendelian randomization study

AIM

The aim of this meta-analysis and Mendelian randomization (MR) study was to assess the association between short sleep and periodontal disease, including tooth loss and periodontitis.

MATERIALS AND METHODS

The meta-analysis of relevant studies was conducted to assess the association between short sleep and periodontal disease. MR analyses were conducted with the inverse-variance-weighted (IVW) method, weighted median method, MR-Egger method, and MR-Robust Adjusted Profile Score (RAPS) method to assess the causal effect of short sleep on tooth loss and periodontitis.

RESULTS

Seven cross-sectional studies involving 40,196 individuals were included in the meta-analysis. The association between short sleep and periodontal disease was not statistically significant (odds ratios (OR) =1.13, 95% confidence interval (CI): 0.99, 1.28; p = 0.076). In the MR analysis, we did not observe statistically significant causal associations of genetically determined short sleep with tooth loss (β: -0.056; 95% CI: -0.181 to 0.068; p = 0.376) and periodontitis (β: -0.112; 95% CI: -0.340 to 0.117; p = 0.339).

CONCLUSIONS

Short sleep is not associated with the risk of periodontal disease according to current evidence. Future studies need to pay attention to the measurement of sleep duration, the choice of statistical models, and other domains of sleep health.

Insomnia symptoms, fatigue, and future job exit in American older adults

BACKGROUND

As older adults prolong working life and face age-related health changes, insomnia symptoms and fatigue may jeopardize their ability to stay in the labor force. Our study explored the relationships between insomnia symptoms, fatigue, and job exit in workers aged 65 years and older.

METHODS

Data from the National Health and Aging Trends Study were used (2011-2017). The sample included 953 Medicare beneficiaries with paid work at the time of the interview. Workers were followed annually for 6 years to the time of job exit. Insomnia measures included the number and type of symptoms, and fatigue (measured as low energy). Crude and adjusted odds ratios and 95% confidence intervals were estimated within discrete-time survival analysis. Models were adjusted for health, lifestyle, and sociodemographic characteristics.

RESULTS

At baseline, approximately 49% of workers had either one or two insomnia symptoms. Difficulty falling asleep and difficulty maintaining asleep were prevalent in 35% and 37% of the sample. Fatigue was common in <30% of the sample. Workers with difficulty falling asleep were 1.29 times at higher odds to have job exit when compared with workers with no insomnia (p = 0.033). Conversely, fatigued workers were 0.73-0.77 times at lower odds to have job exit when compared with nonfatigued workers (p < 0.05).

CONCLUSION

Difficulty falling asleep negatively affects future work status, unlike feeling fatigued. Healthcare providers are encouraged to assess for insomnia and discuss treatments with workers, and workplaces should be flexible with the start of workdays to support worker longevity.

Sleep quality in times of Covid-19 pandemic

BACKGROUND

Due to the 2019 novel coronavirus (COVID-19) disease outbreak, social distancing measures were imposed to control the spread of the pandemic. However, isolation may affect negatively the psychological well-being and impair sleep quality. Our aim was to evaluate the sleep quality of respiratory patients during the COVID-19 pandemic lockdown.

METHODS

All patients who underwent a telemedicine appointment from March 30 to April 30 of 2020 were asked to participate in the survey. Sleep difficulties were measured using Jenkins Sleep Scale.

RESULTS

The study population consisted of 365 patients (mean age 63.9 years, 55.6% male, 50.1% with sleep-disordered breathing [SDB]). During the lockdown, 78.9% of participants were confined at home without working. Most patients (69.6%) reported at least one sleep difficulty and frequent awakenings was the most prevalent problem. Reporting at least one sleep difficulty was associated with home confinement without working, female gender and diagnosed or suspected SDB, after adjustment for cohabitation status and use of anxiolytics. Home confinement without working was associated with difficulties falling asleep and waking up too early in the morning. Older age was a protective factor for difficulties falling asleep, waking up too early and non-restorative sleep. Notably, SDB patients with good compliance to positive airway pressure therapy were less likely to report sleep difficulties.

CONCLUSIONS

Home confinement without working, female gender and SDB may predict a higher risk of reporting sleep difficulties. Medical support during major disasters should be strengthened and potentially delivered through telemedicine, as this comprehensive approach could reduce psychological distress and improve sleep quality.