Social Isolation, Sleep Disturbance, and Cognitive Functioning (HRS): A Longitudinal Mediation Study

Relationship between cognitive function and sleep quality in middle-aged and older adults for minimizing disparities and achieving equity in health: Evidence from multiple nationwide cohorts

BACKGROUND

Cognitive decline, a heavy burden on middle-aged and older adults as global aging is aggravated, was found to be associated with sleep quality. However, the country-between heterogeneity of the association prevented us from quantifying underlying relationship and identifying potential effect modifiers for vulnerable populations and targeted interventions.

METHODS

We collected data from 79,922 eligible adults in five nationwide cohorts, examined the respective relationships between cognitive function and sleep quality, synthesized underlying average relationships by meta-analysis, and explored effect modifiers by meta-regressions. Additionally, we conducted subgroup and interaction analyses to identify vulnerable populations and to determine their disparities in vulnerability.

RESULTS

Although country-between disparities exist, cognitive function is robustly associated with sleep quality in middle-aged and older adults worldwide, with an effect (β) of 0.015 [0.003, 0.027]. Executive function is the subdomain most relevant to sleep quality. Disparities in the effects of sleep quality on subdomains exist in populations with different sexes (orientation: βfemale/βmale = 1.615, P = 0.020), marital statuses (orientation: βunmarried/βmarried = 2.074, P < 0.001), education levels (orientation:βuneducated/βeducated = 2.074, P < 0.001) and chronic disease statuses (memory: βunhealthy/βhealthy = 1.560, P = 0.005).

CONCLUSIONS

Cognitive function decreases with worsening sleep quality in middle-aged and older adults. Vulnerability to poor sleep generally persists in singles, females, the uneducated and people with chronic diseases. To minimize disparities and achieve health equity, we advocate for targeted interventions, i.e., encouraging socialization in singles, confirming effectiveness of hormone replacement therapy in females, employing compulsory education in middle-aged and older adults.

The mutual longitudinal mediating effects of psychological and physical disorders on cognitive impairment among older adults

BACKGROUND

The potential mutual effect of physical and psychological disorders on cognitive function is critical for preventing cognitive impairment among older adults. We aimed to investigate the mediating role of physical and psychological disorders in their associations with cognitive function.

METHODS

We conducted a prospective cohort study using the Health and Retirement Study, involving 5308 adults aged 60 years or older. Physical disorders included seven self-reported physician-diagnosed conditions. Psychological disorder and cognitive function were ascertained using the 8-item Centers for Epidemiologic Research Depression scale and the 27-point HRS cognitive scale, respectively. Multivariable linear regression models were used to assess the association of the baseline scores of physical and psychological disorders with subsequent cognitive scores. Second-order cross-lagged panel models (CLPM) were used to assess the longitudinal mediating roles, respectively.

RESULTS

The higher psychological disorder scores (β = -0.15; P < 0.0001) and physical disorders scores (β = -0.18; P < 0.0001) were, the worse the cognitive function was. CLPM revealed a significant longitudinal mediating effect of baseline physical disorders through changes in psychological disorder from 2002 to 2010 on the cognitive scores changes from 2002 to 2010 (β = -0.02; P < 0.0001). Meanwhile, the longitudinal mediating effect of baseline psychological disorder scores through physical disorders changes from 2002 to 2010 on the cognitive scores changes from 2002 to 2010 was significant (β = -0.004; P = 0.005).

CONCLUSIONS

The mutual longitudinal mediating effects of psychological disorder and physical disorder indicate that among older adults, physical and psychological disorders accelerate cognitive impairment as a whole and mutually reinforcing process.

Effects of physical and psychological multimorbidity on the risk of dementia: multinational prospective cohorts and a meta-analysis

BACKGROUND

Previous studies only considered the impact of a single physical or psychological disorder on dementia. Our study investigated the association of physical and psychological multimorbidity with dementia among older adults using two multinational prospective cohorts to supplement the limited joint evidence.

METHODS

We utilized the Health and Retirement Study (HRS 2012 to 2018) in the United States (US) and the Survey of Health, Ageing and Retirement in Europe (SHARE 2012 to 2018). Physical disorder was defined as any one of seven self-reported physician-diagnosed conditions. Psychological disorder was assessed using the 8-item Center for Epidemiologic Research Depression (CES-D) scale or the EURO-D. Dementia was determined through a combination of self-reported physician diagnosis of dementia or Alzheimer's disease, or the 27-point HRS cognitive scale. Competing risk models were utilized to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CI). DerSimonian-Laird random-effects meta-analyses were conducted to obtain pooled estimates.

RESULTS

The prevalence of physical and psychological multimorbidity was 17.29% (1027/5939) in continental Europe and 15.52% (1326/8543) in the US. The incidence of dementia was 6.21 per 1000 person-years in continental Europe and 8.27 per 1000 person-years in the US, respectively. It was highest among participants with physical and psychological multimorbidity in continental Europe (10.46 per 1000 person-years) and the US (14.82 per 1000 person-years), compared with the other three groups. In the univariate model, participants who reported physical and psychological multimorbidity had a higher risk of dementia compared with those who reported no physical and psychological disorders in continental Europe (HR = 2.59; 95% CI: 1.55, 4.33) and the US (HR = 4.11; 95% CI: 2.44, 6.94). After adjusting all covariates, the risk of dementia among participants who reported physical and psychological multimorbidity increased by 86% in continental Europe (aHR = 1.86; 95% CI: 1.08, 3.21) and by 176% in the US (aHR = 2.76; 95% CI: 1.61, 4.72), respectively. After pooling the outcomes, the risk of dementia among participants who reported physical and psychological multimorbidity increased by 115% (aHR = 2.15; 95% CI: 1.27, 3.03).

CONCLUSIONS

Physical and psychological multimorbidity was prevalent among older adults in the US and continental Europe. Given the consistent associations with dementia, it is imperative to increase awareness of the links and recognize the limitations of single-disorder care. Specific attention should be given to providing care coordination.

Adult day services: a potential antidote to social isolation and loneliness in marginalized older adults

Loneliness and social isolation affect more than 1 in 4 community-dwelling older adults in the United States, who may also require long-term care support. Despite being seen as a solution to the long-term care crisis, most older adults prefer to age in place rather than using skilled nursing facilities. However, in-home care is unsustainable due to a shortage of direct care workers and may exacerbate social isolation by confining older adults to their homes. Adult Day Services (ADS) addresses both issues. ADS provides care to adults with physical, functional, and or cognitive limitations in non-residential, congregate, community-based settings. ADS also provides daily cognitive and physical stimulation, often with medical support, in a social and supported environment, centered around the needs and preferences of participants. Before the COVID-19 pandemic, nearly 5,000 ADS centers were widely available. However, with limited public support, the ADS industry has struggled as demand by the growing number of older adults and families need health and social support. The ADS industry must be recognized for its unique ability to buffer social isolation and loneliness in chronically ill older adults while serving as an effective platform for chronic disease management. This perspective piece highlights the critical role of ADS centers in reducing loneliness and social isolation and promoting healthy equity. We also explore the benefits of ADS, the financial, policy, and societal barriers to utilizing ADS, and the potential solutions to ensure its sustainability and growth.

Mechanisms, consequences and role of interventions for sleep deprivation: Focus on mild cognitive impairment and Alzheimer's disease in elderly

Sleep is established as an essential physiological need that impacts physical, emotional, and cognitive functions profoundly. Physiologically, inadequate sleep weakens immune function, heightening susceptibility to infections and chronic illnesses such as obesity, diabetes, and cardiovascular diseases. Hormonal disruptions due to sleep loss further exacerbate metabolic dysregulation, contributing to weight gain and other health complications. Emotionally, sleep deprivation leads to mood disturbances, including increased irritability, heightened stress responses, and a greater likelihood of mood disorders like depression and anxiety. These effects are compounded by cognitive impairments such as reduced alertness, impaired memory consolidation, and compromised decision-making abilities, akin to the impairments caused by alcohol consumption. Motor skills and coordination also suffer, elevating the risk of accidents, particularly in high-stress environments. For older adults, sleep quality is closely linked to cognitive function and overall longevity. Optimal sleep patterns are associated with slower brain aging and improved health outcomes. However, sleep disorders exacerbate existing conditions such as epilepsy and asthma, necessitating interventions like cognitive behavioral therapy (CBT) and medications such as melatonin to mitigate their impact. Education emerges as a crucial tool in promoting healthier sleep habits across all age groups. Addressing misconceptions about sleep and integrating sleep health into public health policies are essential steps toward improving overall well-being. Additionally, lifestyle factors such as diet and physical activity play significant roles in regulating sleep patterns, further emphasizing the interconnectedness of sleep with broader health outcomes. In summary, the articles underscore the intricate mechanisms through which sleep influences physiological functions and advocate for comprehensive approaches to enhance sleep hygiene and mitigate the adverse effects of sleep deprivation on human health.

Exploring the Influence of Gut-Brain Axis Modulation on Cognitive Health: A Comprehensive Review of Prebiotics, Probiotics, and Symbiotics

Recent research exploring the relationship between the gut and the brain suggests that the condition of the gut microbiota can influence cognitive health. A well-balanced gut microbiota may help reduce inflammation, which is linked to neurodegenerative conditions. Prebiotics, probiotics, and symbiotics are nutritional supplements and functional food components associated with gastrointestinal well-being. The bidirectional communication of the gut-brain axis is essential for maintaining homeostasis, with pre-, pro-, and symbiotics potentially affecting various cognitive functions such as attention, perception, and memory. Numerous studies have consistently shown that incorporating pre-, pro-, and symbiotics into a healthy diet can lead to improvements in cognitive functions and mood. Maintaining a healthy gut microbiota can support optimal cognitive function, which is crucial for disease prevention in our fast-paced, Westernized society. Our results indicate cognitive benefits in healthy older individuals with probiotic supplementation but not in healthy older individuals who have good and adequate levels of physical activity. Additionally, it appears that there are cognitive benefits in patients with mild cognitive impairment and Alzheimer's disease, while mixed results seem to arise in younger and healthier individuals. However, it is important to acknowledge that individual responses may vary, and the use of these dietary supplements should be tailored to each individual's unique health circumstances and needs.

The trajectory of depressive symptoms over time and the presence of depressive symptoms at a single time point with the risk of dementia among US older adults: A national prospective cohort study

AIM

This study aims to assess the association between trajectories of depressive symptoms and the risk of dementia, and to compare the predictive ability of trajectories using multiple data points with depressive symptoms at a single data point.

METHODS

We included 5306 older adults from the Health and Retirement Study. We assessed depressive symptoms using the Center for Epidemiology Depression Scale (CES-D), and identified its 8- year trajectories (2002-2010) using latent class trajectory modeling. We calculated hazard ratios (HR) using Cox proportional hazards models. The concordance index (C-index) was used to compare the discriminative power of the models.

RESULTS

We identified two trajectories of depressive symptoms, characterized by maintaining low CES-D scores, and moderate starting scores that steadily increased throughout the follow-up period. During 40,199 person-years, compared to the low trajectory, the increasing trajectory of depressive symptoms was associated with a higher risk of dementia (HR = 1.35; 95% CI: 1.09-1.67) (C-index = 0.759). For every point increase in the degree of depressive symptoms (CES-D scores) in 2010, the risk of dementia increased by 7% (95% CI: 1.03-1.12) (C-index = 0.760). The presence of depressive symptoms (CES-D scores ≥3) in 2010 was not associated with an increased risk of dementia (HR = 1.18; 95% CI: 0.98-1.43) (C-index = 0.759). The C-index values of cox models showed similar discriminative power.

CONCLUSIONS

The increasing trajectory of depressive symptoms at multiple data points and the degree of depressive symptoms at a single data point were associated with an increased risk of subsequent dementia among older adults.

Trajectories of health conditions and their associations with the risk of cognitive impairment among older adults: insights from a national prospective cohort study

BACKGROUND

The associations between trajectories of different health conditions and cognitive impairment among older adults were unknown. Our cohort study aimed to investigate the impact of various trajectories, including sleep disturbances, depressive symptoms, functional limitations, and multimorbidity, on the subsequent risk of cognitive impairment.

METHODS

We conducted a prospective cohort study by using eight waves of national data from the Health and Retirement Study (HRS 2002-2018), involving 4319 adults aged 60 years or older in the USA. Sleep disturbances and depressive symptoms were measured using the Jenkins Sleep Scale and the Centers for Epidemiologic Research Depression (CES-D) scale, respectively. Functional limitations were assessed using activities of daily living (ADLs) and instrumental activities of daily living (IADLs), respectively. Multimorbidity status was assessed by self-reporting physician-diagnosed diseases. We identified 8-year trajectories at four examinations from 2002 to 2010 using latent class trajectory modeling. We screened participants for cognitive impairment using the 27-point HRS cognitive scale from 2010 to 2018 across four subsequent waves. We calculated hazard ratios (HR) using Cox proportional hazard models.

RESULTS

During 25,914 person-years, 1230 participants developed cognitive impairment. In the fully adjusted model 3, the trajectories of sleep disturbances and ADLs limitations were not associated with the risk of cognitive impairment. Compared to the low trajectory, we found that the increasing trajectory of depressive symptoms (HR = 1.39; 95% CI = 1.17-1.65), the increasing trajectory of IADLs limitations (HR = 1.88; 95% CI = 1.43-2.46), and the high trajectory of multimorbidity status (HR = 1.48; 95% CI = 1.16-1.88) all posed an elevated risk of cognitive impairment. The increasing trajectory of IADLs limitations was associated with a higher risk of cognitive impairment among older adults living in urban areas (HR = 2.30; 95% CI = 1.65-3.21) and those who smoked (HR = 2.77; 95% CI = 1.91-4.02) (all P for interaction < 0.05).

CONCLUSIONS

The results suggest that tracking trajectories of depressive symptoms, instrumental functioning limitations, and multimorbidity status may be a potential and feasible screening method for identifying older adults at risk of cognitive impairment.

The longitudinal bidirectional association between sarcopenia and cognitive function in community-dwelling older adults: Findings from the China Health and Retirement Longitudinal Study

Background

Although an association between sarcopenia and cognitive function has been demonstrated, the directional association remains unclear. The present study aimed to evaluate the longitudinal reciprocal relationship and identify the possible temporal sequence between sarcopenia and cognitive function in older Chinese adults.

Methods

Data were collected from the China Health and Retirement Longitudinal Study (CHARLS) baseline survey in 2011 and the follow-up survey in 2015. Cognitive function was measured by episodic memory and executive function. Sarcopenia status (non-sarcopenia, possible sarcopenia and sarcopenia) was defined based on the Asian Working Group for Sarcopenia 2019 criteria. Linear regression analysis and ordinal logistic regression analysis were employed to investigate the relationship between baseline sarcopenia status and follow-up cognition, as well as the association of baseline cognition with follow-up sarcopenia status, respectively. A cross-lagged panel analysis was performed to simultaneously evaluate the bidirectional association and the strength of the temporal relationship.

Results

Of 2689 participants, the median age was 65.0 years and 1249 (46.5%) were female. After adjusting for potential confounders and baseline measurements, baseline sarcopenia status was dose-dependently associated with subsequent cognitive scores (β = -0.45; P for trend = 0.001), and baseline cognitive scores (in tertiles) were also dose-dependently associated with subsequent sarcopenia status (odds ratio (OR) = 0.86; P for trend = 0.017). The cross-lagged panel analysis indicated that the standardised effect size of sarcopenia status on cognitive function (β = -0.09; P < 0.001) is larger relative to the effect of cognitive function on sarcopenia status (β = -0.05; P = 0.019).

Conclusions

There is a longitudinal, bidirectional relationship between sarcopenia status and cognitive function in older Chinese adults. Sarcopenia is likely the driving force in these dynamic associations. These findings imply that interventions in either sarcopenia or cognitive decline may have the ability to generate reciprocal benefits over time. More research is warranted to confirm these findings and to further elucidate underlying causal pathways.

Home-Delivered Meals and Nursing Home Placement Among People With Self-Reported Dementia: A Pilot Pragmatic Clinical Trial

Importance

Home-delivered meals promote food security and independence among homebound older adults. However, it is unclear which of the 2 predominant modes of meal delivery, daily-delivered vs mailed (or drop-shipped) frozen meals, promotes community living for homebound older adults with dementia.

Objective

To assess the risk of nursing home admission within 6 months between homebound individuals receiving daily-delivered vs drop-shipped frozen meals.

Design, Setting, and Participants

This pilot, multisite, 2-arm, pragmatic clinical trial included older adults with self-reported dementia on waiting lists for meals at 3 Meals on Wheels (MOW) programs in Texas and Florida between April 7 and October 8, 2021, to assess time to nursing home placement.

Interventions

Participants were randomized to receive either meals delivered by an MOW driver or frozen meals that were mailed to participants' homes every 2 weeks. Participants received their assigned intervention for up to 6 months.

Main Outcomes and Measures

The primary study outcome was days from randomization to a Minimum Data Set nursing home admission assessment within 6 months. Feasibility of conducting this type of study was examined by tracking enrollment, examining baseline characteristics, monitoring participants' intervention fidelity, measuring the proportion of participants linked with Centers for Medicare & Medicaid Services (CMS) data, and analyzing the primary study outcome.

Results

Among 325 eligible participants who were randomized, 243 enrolled in the study (mean [SD] age, 81 [8.0] years; 152 (62.6%) were female): 128 to the daily-delivered meals group and 115 to the drop-shipped frozen meals group; 119 participants (49.0%) lived alone. Among the total participants enrolled, 227 (93.4%) were linked deterministically to their CMS data; probabilistic methods were used to link the remaining 16 participants (6.6%). At 6 months from randomization, 160 participants (65.8%) were still receiving meals, and 25 (10.1%; 95% CI, 6.3%-14.0%) were admitted to a nursing home. After adjusting for sex, race and ethnicity, age, program, and living arrangement and the use of death as a censoring event, the adjusted log hazard ratio of nursing home placement between daily-delivered and drop-shipped frozen meals was -0.67 (95% CI, -1.52 to 0.19).

Conclusions and Relevance

This pilot randomized clinical trial demonstrated the feasibility of enrolling participants with self-reported dementia on waiting lists at MOW programs, linking their data, and evaluating outcomes. While this pilot study was not powered to detect meaningful, statistically significant differences in nursing home placement, its feasibility and initial results warrant exploration in a follow-on, adequately powered trial.

Trial Registration

ClinicalTrials.gov Identifier: NCT04850781.

Sleep disturbance and medical requests among university and college students in Chongqing, China: A cross-sectional study

OBJECTIVES

To investigate the prevalence of sleep disturbance, sleep patterns, sleep-related factors, and medical demands among university and college students in Chongqing, China.

METHODS

Demographic data and responses to the sleep problem questionnaire (SPQ) were collected from 1973 students from 11 universities and 10 colleges between November 2022 and January 2023.

RESULTS

The prevalence of sleep disturbance in university and college students was different in different periods (58.17% during campus lockdown and 40.30% after the lifting of lockdown). The combined prevalence was 49.72%. The prevalence of the 6 types of sleep disturbance showed the same trend. The average sleep latency was 32.79 minutes and the average sleep duration was 7.53 hours. Male, university students, upper-class students, history of depression, academic stress, major life events, bad bedroom environment, and campus lockdown were factors related to sleep disturbance among respondents. Most of the respondents (52.09%) had no medical care requests, and the major reasons were a lack of access to medical care (75.15%), economic pressure (68.49%), concerns regarding curative effects (58.51%), and academic pressure (56.56%).

CONCLUSION

The prevalence of sleep disturbance for university and college students was obviously improved after the lifting of campus lockdown, and the major factors related to sleep disturbance were study, life, mental health, and sleep environment. The students examined herein reported relatively low medical care requests when they experience sleep disturbance.

Social isolation, loneliness, and incident type 2 diabetes mellitus: results from two large prospective cohorts in Europe and East Asia and Mendelian randomization

Background

Social isolation and loneliness pose significant public health challenges globally. The objective of this study is to investigate the association between social isolation, loneliness, and the risk of type 2 diabetes mellitus (T2DM).

Methods

423,503 UK adults from the UK Biobank (UKB) and 13,800 Chinese adults from the China Health and Retirement Longitudinal Study (CHARLS) were analyzed. The exposures of interest were social isolation and loneliness. Social isolation was evaluated based on the number of household members, frequency of social activities, contact with others, and marriage status (CHARLS only). Loneliness was evaluated by the subjective feeling of loneliness and the willingness to confide in others (UKB only). The primary endpoint was incident T2DM. The two-sample Mendelian randomization (MR) analysis was based on the genome-wide association studies of UKB (n = 463,010) and the European Bioinformatics Institute (n = 655,666).

Findings

The UKB cohort study documented 15,072 T2DM cases during a mean follow-up of 13.5 years, and the CHARLS cohort study recorded 1,249 T2DM cases during a mean follow-up of 5.8 years. Social isolation and loneliness showed significant associations with an elevated risk of T2DM in both UKB (social isolation [most vs least]: HR 1.17, 95% CI 1.11-1.23; loneliness [yes vs no]: HR 1.21, 95% CI 1.13-1.30) and CHARLS cohorts (social isolation [yes vs no]: HR 1.22, 95% CI 1.06-1.40; loneliness [yes vs no]: HR 1.21, 95% CI 1.07-1.36). These associations remained significant after accounting for baseline glucose status and genetic susceptibility to T2DM. Two-sample MR analyses determined that feeling lonely (OR 1.04, 95% CI 1.02-1.06) and engaging in fewer leisure/social activities (OR 1.03, 95% CI 1.02-1.05) were associated with increased T2DM risk, whereas more contact with friends or family (OR 0.99, 95% CI 0.98-0.99) was associated with reduced T2DM risk.

Interpretation

Social isolation and loneliness are each associated with an elevated risk of T2DM, with MR analyses suggesting potential causal links. These associations remain significant after considering genetic susceptibility to T2DM. The findings highlight the importance of promoting initiatives to address social isolation and loneliness as part of T2DM prevention strategies.

Funding

CAMS Innovation Fund for Medical Sciences (No. 2021-I2M-1-008) and National Natural Science Foundation of China (No. 72103187).

Association Between Types of Loneliness and Risks of Functional Disability in Older Men and Women: A Prospective Analysis

OBJECTIVE

To examine the association between types of loneliness (transient, incident, and chronic) and the risk of functional disability.

METHODS

Data were from the Health and Retirement Study 2006/2008-2016/2018. A total of 7,148 adults aged ≥50 was included. Functional status was measured by activities of daily living (ADL) and instrumental activities of daily living (IADL). Loneliness was assessed using the 3-item UCLA Loneliness Scale. We defined loneliness as no/transient/incident/chronic loneliness based on the pattern and duration of loneliness across 2006/2008 and 2010/2012. We applied multivariate Cox proportional hazard models with the new-onset ADL/IADL disability as outcome.

RESULTS

Overall, 69.3% respondents showed no loneliness; while 10.3%, 8.9%, and 11.5% showed transient, incident, and chronic loneliness, respectively. A total of 1,298 (18.16%) and 1,260 (17.63%) functionally normal respondents developed ADL and IADL disability during 36,294 person-years of follow-up, respectively. After adjusting for socio-demographic, behavioral, and health factors, chronic loneliness was associated with higher risks of ADL (hazard ratio [HR] = 1.37, 95% confidence interval [CI] = 1.16-1.63, p <0.001, χ2 = 3.60, degree of freedom [df] = 1) and IADL disability (HR = 1.25, 95% CI = 1.09-1.44, p = 0.002, χ2 = 3.17, df = 1) compared to no loneliness. By contrast, no significant associations between transient loneliness and ADL (HR = 1.17, 95% CI = 0.88-1.57, p = 0.273, χ2 = 1.10, df = 1) or IADL disability (HR = 1.16, 95% CI = 0.97-1.39, p = 0.112, χ2 = 1.59, df = 1) were found. Chronic loneliness was not associated with the risk of IADL disability in men (HR = 1.13, 95% CI = 0.91-1.40, p = 0.263, χ2 = 1.12, df = 1).

CONCLUSION

Chronic loneliness, rather than transient loneliness, is an independent risk factor for functional disability in middle-aged and older adults, especially for women.

Associations of social isolation and loneliness with the onset of insomnia symptoms among middle-aged and older adults in the United States: A population-based cohort study

There is an inconsistent conclusion regarding the relationship of social isolation and loneliness with poor sleep. We investigated the associations of social isolation and loneliness with new-onset insomnia symptoms in a nationally-representative sample of 9,430 adults aged ≥50 who were free of any insomnia symptoms/sleep disorders at baseline (wave 12/13) and followed up to 4 years from the Health and Retirement Study. Social isolation was measured by Steptoe's Social Isolation Index. Loneliness was measured by the revised 3-item UCLA-Loneliness Scale. Insomnia symptoms were quantified using the modified Jenkins Sleep Questionnaire. During a mean follow-up of 3.52 years, 1,522 (16.1%) participants developed at least one insomnia symptom. Cox models showed that loneliness was associated with the onset of difficulties initiating or maintaining sleep, early-morning awakening, nonrestorative sleep, and at least one of these symptoms after adjusting for potential covariates; while social isolation was not associated with the onset of difficulties maintaining sleep, early-morning awakening, or at least one insomnia symptom after adjusting for health indicators. These results are consistent in sensitivity analyses and stratified analyses by age, sex, race/ethnicity, and obesity. Public health interventions aimed at fostering close emotional relationships may reduce the burden of poor sleep among middle-aged and older adults.