Differences in sleep timing and related effects between African Americans and non-Hispanic Whites

Midpoint of sleep is associated with sleep quality in older adults with and without symptomatic Alzheimer's disease

Introduction

Disrupted sleep is common in individuals with Alzheimer's disease (AD) and may be a marker for AD risk. The timing of sleep affects sleep-wake activity and is also associated with AD, but little is known about links between sleep architecture and the midpoint of sleep in older adults. In this study, we tested if the midpoint of sleep is associated with different measures of sleep architecture, AD biomarkers, and cognitive status among older adults with and without symptomatic AD.

Methods

Participants (N = 243) with a mean age of 74 underwent standardized cognitive assessments, measurement of CSF AD biomarkers, and sleep monitoring via single-channel EEG, actigraphy, a home sleep apnea test, and self-reported sleep logs. The midpoint of sleep was defined by actigraphy.

Results

A later midpoint of sleep was associated with African-American race and greater night-to-night variability in the sleep midpoint. After adjusting for multiple potential confounding factors, a later sleep midpoint was associated with longer rapid-eye movement (REM) onset latency, decreased REM sleep time, more actigraphic awakenings at night, and higher < 2 Hz non-REM slow-wave activity.

Conclusions

Noninvasive in vivo markers of brain function, such as sleep, are needed to track both future risk of cognitive impairment and response to interventions in older adults at risk for AD. Sleep timing is associated with multiple other sleep measures and may affect their utility as markers of AD. The midpoint of sleep may be changed through behavioral intervention and should be taken into account when using sleep as a marker for AD risk.

Circadian preference and physical and cognitive performance in adolescence: A scoping review

Adolescence is a crucial period of development which coincides with changes in circadian rhythmicity. This may augment the impact of circadian preference on performance in this group. We aimed to scope the literature available on chronotypes and their effect on physical and mental aspects of performance in adolescents. Studies were identified by systematically searching bibliographical databases and grey literature. The Morningness-Eveningness Questionnaire was the most frequently reported tool for circadian preference assessment. Academic achievement was the most prevailing outcome, with evidence suggesting that morning type adolescents tend to outperform evening types, yet the results vary depending on multiple factors. Performance in tests of intelligence and executive functions was generally better at optimal times of the day (synchrony effect). Physical performance was examined in 8 studies, with very heterogeneous outcomes. Although the associations between circadian preference and performance in adolescents are evident in some areas, there are many factors that may be involved in the relationship and require further investigation. This review highlights the assessment of physical performance in relation to chronotypes, the multidimensional assessment of circadian preference, and the need for longitudinal studies as priorities for further research.Protocol: OSF Registration - Public registration, DOI: 10.17605/OSF.IO/UCA3Z.

Sleep timing, sleep regularity, and psychological health in early late life women: Findings from the Study of Women's Health Across the Nation (SWAN)

OBJECTIVES

To examine the associations of actigraphy-assessed sleep timing and regularity with psychological health in early late life women, whose circadian rhythms may be impacted by aging.

DESIGN

Cross-sectional.

PARTICIPANTS

A racially/ethnically diverse sample of 1197 community-dwelling women (mean age 65 years) enrolled in the Study of Women's Health Across the Nation.

MEASURES

Actigraphy-assessed sleep measures included timing (mean midpoint from sleep onset to wake-up) and regularity (standard deviation of midpoint in hours). Psychological health measures included a composite well-being score, the Center for Epidemiological Studies Depression Scale, and the Generalized Anxiety Disorder-7 Scale. Linear and logistic regression models, adjusted for covariates (including sleep duration), tested associations between sleep and psychological health measures.

RESULTS

After covariate adjustment, a sleep midpoint outside of 2:00-4: 00 AM was significantly associated with depressive symptoms (β = 0.88, 95% CI = 0.06, 1.70) and scoring above the cut-point for clinically significant depressive symptoms (OR = 1.72, 95% CI = 1.15, 2.57). Sleep irregularity was significantly associated with lower psychological well-being (β = -0.18, 95% CI = -0.33, -0.03), depressive (β = 1.36, 95% CI = 0.29, 2.44) and anxiety (β = 0.93, 95% CI = 0.40, 1.46) symptoms, and scoring above the cut-point for clinically significant depressive (OR = 1.68, 95% CI = 1.01, 2.79) and anxiety (OR = 1.62, 95% CI = 1.07, 2.43) symptoms.

CONCLUSION

Above and beyond sleep duration, a sleep midpoint outside of 2:00-4:00 AM was associated with depressive symptoms while sleep irregularity was associated with multiple psychological health domains in late life women.

Understanding the determinants of circadian health disparities and cardiovascular disease

Emerging research suggests that sleep contributes to racial disparities in cardiovascular disease (CVD). Racial/ethnic minorities are disproportionately affected by poor cardiovascular outcomes including obesity, hypertension and diabetes. Although circadian rhythms affect sleep patterns, few studies have examined disparities in circadian health or the contribution of circadian disparities to CVD. In this paper, we provide an overview of the relation between circadian health and CVD in the context of health disparities. We discuss (1) the current knowledge on racial disparities in circadian health; (2) social and environmental determinants of circadian health disparities; (3) the cardiovascular consequences of circadian disparities; and (4) future opportunities to advance the field of circadian disparities. In brief, our findings demonstrated that among a small literature, racial minorities (mainly African American) were more likely to have a shorter circadian period, delayed phase shifts, and were more likely to be shift workers, which are associated with CVD risk factors. Given racial minorities are disproportionately affected by CVD and CVD risk factors, it is important to further understand circadian health as an intervention target and support more research among racial minorities to understand circadian health in these populations.

Rest-activity profiles among U.S. adults in a nationally representative sample: a functional principal component analysis

Background

The 24-h rest and activity behaviors (i.e., physical activity, sedentary behaviors and sleep) are fundamental human behaviors essential to health and well-being. Functional principal component analysis (fPCA) is a flexible approach for characterizing rest-activity rhythms and does not rely on a priori assumptions about the activity shape. The objective of our study is to apply fPCA to a nationally representative sample of American adults to characterize variations in the 24-h rest-activity pattern, determine how the pattern differs according to demographic, socioeconomic and work characteristics, and examine its associations with general health status.

Methods

The current analysis used data from adults 25 or older in the National Health and Nutrition Examination Survey (NHANES, 2011–2014). Using 7-day 24-h actigraphy recordings, we applied fPCA to derive profiles for overall, weekday and weekend rest-activity patterns. We examined the association between each rest-activity profile in relation to age, gender, race/ethnicity, education, income and working status using multiple linear regression. We also used multiple logistic regression to determine the relationship between each rest-activity profile and the likelihood of reporting poor or fair health.

Results

We identified four distinct profiles (i.e., high amplitude, early rise, prolonged activity window, biphasic pattern) that together accounted for 86.8% of total variation in the study sample. We identified numerous associations between each rest-activity profile and multiple sociodemographic characteristics. We also found evidence suggesting the associations differed between weekdays and weekends. Finally, we reported that the rest-activity profiles were associated with self-rated health.

Conclusions

Our study provided evidence suggesting that rest-activity patterns in human populations are shaped by multiple demographic, socioeconomic and work factors, and are correlated with health status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-022-01274-4.