Associations of Actigraphic Sleep Parameters With Fatigability in Older Adults

Accelerometer-assessed sleep and decline in physical function in older men

OBJECTIVES

Assess the prospective association of actigraphically measured sleep with self-report and objective measures of physical function among community-dwelling older men.

METHODS

Participants were (n = 1496) men aged ≥65 years from the Osteoporotic Fractures in Men Study and ancillary sleep study who were followed up at 4 years for physical function outcomes. Sleep predictors included baseline total sleep time (<6, 6-8 hours [reference], >8 hours), sleep efficiency (<80% or ≥80% [reference]), wake after sleep onset (<90 [reference] or ≥90 minutes), and sleep onset latency (<30 [reference] or ≥30 minutes), measured by wrist actigraphy. Outcomes included self-reported difficulties in mobility and instrumental activities of daily living and objective measures of physical performance (time to complete chair stands, gait speed, grip strength, best narrow walk pace). Multivariable regression models estimated associations between the sleep predictors and change in physical function at follow-up, adjusting for demographic and health-related variables.

RESULTS

Participants with short average baseline total sleep time (<6 hours) had significantly greater slowing in their walking speed from baseline to follow-up. Participants with long baseline sleep onset latency (≥30 minutes) had significant increases in mobility difficulties and time to complete chair stands. Sleep efficiency and wake after sleep onset were not significantly associated with any outcomes. No sleep predictors were associated with change in instrumental activities of daily living.

CONCLUSIONS

These findings add to the body of evidence showing links between poor sleep and subsequent declines in physical function. Further experimental research is needed to understand the mechanisms at play.

Association between prior-night sleep and next-day fatigue in older adults: a daily diary study

BACKGROUND

Fatigue is known as an element of frailty. Sleep problems (e.g., short sleep duration and low sleep quality) can increase fatigue, but the day-to-day relationship between sleep and fatigue has not been studied well in older adults. Using a daily diary method, this study examined the within- and between-person associations between sleep and fatigue in older adults.

METHODS

The study recruited 56 Japanese community dwellers (age: 82-86 years; female: 37.5%). Participants responded to a daily diary questionnaire at the end of each day. Over seven days, time in bed and satisfaction were measured after waking up, whereas fatigue was assessed before going to bed. We included person-level covariates (demographic factors, and physical and mental health) and day-level covariates (time in study, and positive and negative emotions). Multilevel models were estimated to examine within- and between-person associations.

RESULTS

At the within-person level, on days following short and long time in bed and days following low levels of sleep satisfaction, individuals felt higher levels of fatigue compared with usual days. At the between-person level, no statistically significant differences in fatigue were observed between individuals with long and short time in bed.

CONCLUSIONS

The findings suggest that prior-day sleep is associated with next-day fatigue in older adults. Long and short sleep duration and low sleep quality can lead to fatigue. Considering that sleep is a modifiable health behavior, appropriate management of sleep behavior may reduce fatigue.

Measuring and Understanding the Health Impact of Greater Fatigability in Older Adults: A Call to Action and Opportunities

Different from fatigue, an instantaneous state of tiredness, weakness and lack of energy, fatigability is a trait that contextualizes whole-body fatigue to the level of activity (i.e., intensity and duration) with which the fatigue is associated. Fatigability can be perceived or performance-related. Measuring fatigability improves upon traditional fatigue measures by accounting for self-pacing as older adults likely slow down or limit their daily activity to maintain fatigue in a tolerable range. Anchoring fatigue to activities/tasks improves sensitivity and allows for meaningful comparisons across individuals/between studies, as well as evaluating change over time and treatment effects. Two well-validated approaches are utilized to measure perceived fatigability: 1) a 5-minute slow-paced (1.5 mph/0.67 m/s, 0% grade) treadmill walk immediately followed by Borg rating of perceived exertion; and 2) a self-administered 10-item questionnaire, Pittsburgh Fatigability Scale, with both physical and mental subscales. Many walking-based performance fatigability measures are based on certain lap time or distance, while the Pittsburgh Performance Fatigability Index uses raw accelerometry data to quantify percent of cadence decline over the entire long distance walking tasks. Perceived fatigability prevalence ranges from 20-90% in older adults varying by assessment tool, and is higher with advancing age and in women compared to men. Fatigability is associated with physical and cognitive function, fall risk, mobility decline, and mortality. Unfortunately, the available research lacks representativeness in terms of racial and ethnic diversity. The time is now to incorporate our established sensitive and validated fatigability measures into global research and clinical practice to better understand mechanistic underpinnings and reveal intervention effects to reduce the burden and lessen the consequences of greater fatigability worldwide.

Association between sleep health and intrinsic capacity among older adults in Taiwan

Although the association between poor sleep quality and frailty has been previously reported, the relationship between sleep health and intrinsic capacity (IC) remains largely unknown. We aimed to examine the association between sleep health and IC among older adults. This was a cross-sectional study, and 1268 eligible participants completed a questionnaire collecting information on demographic, socioeconomic, lifestyle, sleep health, and IC. Sleep health was measured by the RU-SATED V2.0 scale. High, moderate, and low levels of IC were defined using the Integrated Care for Older People Screening Tool for Taiwanese. The ordinal logistic regression model estimated the odds ratio and corresponding 95% confidence interval. Low IC was significantly associated with age of 80 years or above, female, currently unmarried, uneducated, currently not working, financially dependent, and having emotional disorders. A one-point increase in sleep health was significantly associated with a 9% reduction in the odds of poor IC. An increase in daytime alertness was related to the greatest reduction in poor IC (aOR, 0.64; 95% CI, 0.52-0.79). In addition, the subitems sleep regularity (aOR, 0.77; 95% CI, 0.60-0.99), sleep timing (aOR, 0.80; 95% CI, 0.65-0.99), and sleep duration (aOR, 0.77; 95% CI, 0.61-0.96) were associated with a reduced OR of poor IC but with marginal statistical significance. Our findings showed that sleep health across multiple dimensions is related to IC, particularly daytime alertness in older adults. We suggest developing interventions to improve sleep health and prevent IC decline, which is crucial in causing poor health outcomes.

Free-Living Gait Cadence Measured by Wearable Accelerometer: A Promising Alternative to Traditional Measures of Mobility for Assessing Fall Risk

BACKGROUND

Wearable devices have become widespread in research applications, yet evidence on whether they are superior to structured clinic-based assessments is sparse. In this manuscript, we compare traditional, laboratory-based metrics of mobility with a novel accelerometry-based measure of free-living gait cadence for predicting fall rates.

METHODS

Using negative binomial regression, we compared traditional in-clinic measures of mobility (6-minute gait cadence, speed, and distance, and 4-m gait speed) with free-living gait cadence from wearable accelerometers in predicting fall rates. Accelerometry data were collected with wrist-worn Actigraphs (GT9X) over 7 days in 432 community-dwelling older adults (aged 77.29 ± 5.46 years, 59.1% men, 80.2% White) participating in the Study to Understand Fall Reduction and Vitamin D in You. Falls were ascertained using monthly calendars, quarterly contacts, and ad hoc telephone reports. Accelerometry-based free-living gait cadence was estimated with the Adaptive Empirical Pattern Transformation algorithm.

RESULTS

Across all participants, free-living cadence was significantly related to fall rates; every 10 steps per minute higher cadence was associated with a 13.2% lower fall rate (p = .036). Clinic-based measures of mobility were not related to falls (p > .05). Among higher-functioning participants (cadence ≥100 steps/minute), every 10 steps per minute higher free-living cadence was associated with a 27.7% lower fall rate (p = .01). In participants with slow baseline gait (gait speed <0.8 m/s), all metrics were significantly associated with fall rates.

CONCLUSION

Data collected from biosensors in the free-living environment may provide a more sensitive indicator of fall risk than in-clinic tests, especially among higher-functioning older adults who may be more responsive to intervention.

CLINICAL TRIAL REGISTRATION

NCT02166333.

Does sleep duration moderate genetic and environmental contributions to cognitive performance?

While prior research has demonstrated a relationship between sleep and cognitive performance, how sleep relates to underlying genetic and environmental etiologies contributing to cognitive functioning, regardless of the level of cognitive function, is unclear. The present study assessed whether the importance of genetic and environmental contributions to cognition vary depending on an individual's aging-related sleep characteristics. The large sample consisted of twins from six studies within the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium spanning mid- to late-life (Average age [Mage] = 57.6, range = 27-91 years, N = 7052, Female = 43.70%, 1525 complete monozygotic [MZ] pairs, 2001 complete dizygotic [DZ] pairs). Quantitative genetic twin models considered sleep duration as a primary moderator of genetic and environmental contributions to cognitive performance in four cognitive abilities (Semantic Fluency, Spatial-Visual Reasoning, Processing Speed, and Episodic Memory), while accounting for age moderation. Results suggested genetic and both shared and nonshared environmental contributions for Semantic Fluency and genetic and shared environmental contributions for Episodic Memory vary by sleep duration, while no significant moderation was observed for Spatial-Visual Reasoning or Processing Speed. Results for Semantic Fluency and Episodic Memory illustrated patterns of higher genetic influences on cognitive function at shorter sleep durations (i.e. 4 hours) and higher shared environmental contributions to cognitive function at longer sleep durations (i.e. 10 hours). Overall, these findings may align with associations of upregulation of neuroinflammatory processes and ineffective beta-amyloid clearance in short sleep contexts and common reporting of mental fatigue in long sleep contexts, both associated with poorer cognitive functioning.

Gender Differences in Disease, Function, and Behavioral Symptoms in Residents with Dementia

The purpose of this study was to consider gender differences in depressive symptoms, agitation, resistiveness to care, physical function, and use of psychotropic medications in older adults with moderate to severe dementia in nursing homes. Sixty-seven nursing homes and 889 residents from two states were included. The majority of the participants were female (n = 640, 72%) and White (n = 618, 70%) with a mean age of 86.58 years (SD = 10.31). Differences by gender with regard to age, physical function, depressive symptoms, agitation/aggression, and resistiveness to care were tested using multivariate analysis of variance. Older females with moderate to severe dementia present with more depressive symptoms (anxiety, sadness, and somatic complaints) than males. Males present with more aggressive behavior and are more likely to receive anticonvulsants. Caregivers should focus on preventing and managing depressive symptoms including anxiety, sadness, and somatic complaints among older females and aggressive behavior in older males with dementia.

Daily Physical Activity Patterns as a Window on Cognitive Diagnosis in the Baltimore Longitudinal Study of Aging (BLSA)

BACKGROUND

Gradual disengagement from daily physical activity (PA) could signal present or emerging mild cognitive impairment (MCI) or Alzheimer's disease (AD).

OBJECTIVE

This study examined whether accelerometry-derived patterns of everyday movement differ by cognitive diagnosis in participants of the Baltimore Longitudinal Study of Aging (BLSA).

METHODS

Activity patterns, overall and by time-of-day, were cross-sectionally compared between participants with adjudicated normal cognition (n = 549) and MCI/AD diagnoses (n = 36; 5 participants [14%] living with AD) using covariate-adjusted regression models.

RESULTS

Compared to those with normal cognition, those with MCI/AD had 2.1% higher activity fragmentation (SE = 1.0%, p = 0.036) but similar mean total activity counts/day (p = 0.075) and minutes/day spent active (p = 0.174). Time-of-day analyses show MCI/AD participants had lower activity counts and minutes spent active during waking hours (6:00 am-5:59 pm; p < 0.01 for all). Also, they had lower activity fragmentation from 12:00-5:59 am (p < 0.001), but higher fragmentation from 12:00-5:59 pm (p = 0.026).

CONCLUSION

Differences in the timing and patterns of physical activity throughout the day linked to MCI/AD diagnoses warrant further investigation into potential clinical utility.

Correlates of objective sleep quality in older peritoneal dialysis patients

BACKGROUND

Sleep disturbance is a prominent concern in dialysis patients and detrimentally impacts clinical and self-reported health outcomes. This study aimed to collect sleep data from in-home actigraphy and to explore possible predictors of sleep quality in older peritoneal dialysis patients.

METHODS

This was a cross-sectional study. Peritoneal dialysis patients aged ≥60 years participated in this study. For each participant, sleep quality was assessed by analyzing the data produced by an actigraphic device worn on the wrist 24 h a day for seven consecutive days. Physical function was assessed using handgrip strength and the Timed Up and Go test. Depression was assessed using the self-reported Geriatric Depression Scale. Multiple linear regression analyses were performed to examine the factors influencing sleep efficiency and sleep time.

RESULTS

Based on data collected from 50 participants (N = 50, mean age 70.4 years, 70% male), including 333 nights of actigraphy-monitored sleep, the mean sleep efficiency was 75.5%±14.2% and the mean total sleep time 391.0 ± 99.3 min per night. Higher hemoglobin (β = 0.38, p = 0.007) and lower serum phosphorus (β = -0.30, p = 0.042) levels were significant predictors of better sleep efficiency. The only significant predictor of the total sleep time was age (β = 0.32, p = 0.021).

CONCLUSION

Older peritoneal dialysis patients had poor sleep, characterized by low sleep efficiency. Low hemoglobin and high serum phosphorus levels were predictors of poor sleep efficiency and, as such, modifiable factors for clinicians to consider when treating patients with sleep complaints.

Traits and treadmills: Association between personality and perceived fatigability in well-functioning community-dwelling older adults

Physical fatigability, or susceptibility to physical fatigue, is strongly associated with aging, disease, and disability. Over the lifecourse, personality traits are also connected to numerous age-related vulnerabilities and resistance-yet, their longitudinal association with fatigability remains unknown. Well-functioning community-dwelling volunteers aged ≥50 (N = 995) from the Baltimore Longitudinal Study of Aging (BLSA) were assessed over an average of 2 years on personality traits (NEO-PI-R; openness, conscientiousness, extraversion, agreeableness, and neuroticism) and perceived fatigability [Borg Rating of Perceived Exertion (RPE) after a 5-min slow treadmill walk; 6 (low) to 20 (high) exertion]. Linear and multinomial logistic regression models examined cross-sectional associations [treating fatigability continuously and by RPE category: low (6-7), intermediate (8-9), and high (10+)]. Generalized estimating equations (GEE) tested longitudinal associations. All models were adjusted for demographics and comorbid conditions. In cross-sectional models, openness, β = -.09 RPE (SE =.03); p < .01, conscientiousness, β = -.07 (.03); p < .05, and extraversion, β = -.10 (.03); p < .01, were negatively associated with fatigability. In parallel, lower openness, OR: .98, 95% CI [.96-1.00], conscientiousness, OR: .98, 95% CI [.96-1.00], and extraversion, OR: .97, 95% CI [.95-.99], corresponded with higher odds of having high versus low fatigability. In longitudinal models (mean follow-up time 2 ± 2 years), openness, conscientiousness, and extraversion associations remained significant and did not change over time (Trait × Year p values > .34). Together, findings suggest that personality plays a role in the perceived tolerance of fatigue in well-functioning older adults. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Profiles of Accelerometry-Derived Physical Activity Are Related to Perceived Physical Fatigability in Older Adults

Physical activity (PA) is associated with greater fatigability in older adults; little is known about magnitude, shape, timing and variability of the entire 24-h rest–activity rhythm (RAR) associated with fatigability. We identified which features of the 24-h RAR pattern were independently and jointly associated with greater perceived physical fatigability (Pittsburgh Fatigability Scale, PFS, 0–50) in older adults (n = 181, 71.3 ± 6.7 years). RARs were characterized using anti-logistic extended cosine models and 4-h intervals of PA means and standard deviations across days. A K-means clustering algorithm approach identified four profiles of RAR features: “Less Active/Robust”, “Earlier Risers”, “More Active/Robust” and “Later RAR”. Quantile regression tested associations of each RAR feature/profile on median PFS adjusted for age, sex, race, body mass index and depression symptomatology. Later rise times (up mesor; β = 1.38, p = 0.01) and timing of midpoint of activity (acrophase; β = 1.29, p = 0.01) were associated with higher PFS scores. Lower PA between 4 a.m. and 8 a.m. was associated with higher PFS scores (β = −4.50, p = 0.03). “Less Active/Robust” (β = 6.14, p = 0.01) and “Later RAR” (β = 3.53, p = 0.01) patterns were associated with higher PFS scores compared to “Earlier Risers”. Greater physical fatigability in older adults was associated with dampened, more variable, and later RARs. This work can guide development of interventions aimed at modifying RARs to reduce fatigability in older adults.

Impact of exercise on older adults' mood is moderated by sleep and mediated by altered brain connectivity

Older adults comprise the fastest growing global demographic and are at increased risk of poor mental health outcomes. Although aerobic exercise and sleep are critical to the preservation of emotional well-being, few studies have examined their combined mood-enhancing effects, or the potential neural mechanisms underlying these effects. Here, we used a randomized crossover design to test the impact of acute exercise on mood and the intrinsic functional connectivity (iFC) of the cingulo-opercular network in physically healthy older adults. Wrist actigraphy provided objective indices of sleep. Results revealed that 30 min of moderate-intensity aerobic exercise acutely enhanced positive affect (PA) and reduced iFC between the cingulo-opercular network and the hippocampus. Both effects were magnified among older adults with greater sleep disturbance. Exercise-induced changes in hippocampal iFC mediated relations between sleep disturbance and exercise-induced increases in PA. These findings provide evidence that aerobic exercise enhances mood, that it does so by altering connectivity between the anterior insula-a key hub in the cingulo-opercular network-and the hippocampus and that lower sleep quality is a stronger predictor of these effects among older adults. These observations underscore the benefits of moderate-intensity exercise-a safe and scalable behavioral intervention-and provide new clues about the neural circuitry underlying the interactive effects of sleep and exercise on mood.