Longitudinal associations between insomnia symptoms and all-cause mortality among middle-aged and older adults: A population-based cohort study

To date, there is no scientific consensus on whether insomnia symptoms increase mortality risk. We investigated longitudinal associations between time-varying insomnia symptoms (difficulty initiating sleep, difficulty maintaining sleep, early-morning awakening, and non-restorative sleep) and all-cause mortality among middle-aged and older adults during 14 years of follow-up. Data were obtained from 2004 through 2018 survey waves of the Health and Retirement Study in the United States for a population-representative sample of 15,511 respondents who were ≥50 years old in 2004. Respondents were interviewed biennially and followed through the end of the 2018 survey wave for the outcome. Marginal structural discrete-time survival analyses were employed to account for time-varying confounding and selection bias. Of the 15,511 cohort respondents (mean [±SD] age at baseline, 63.7 [±10.2] years; 56.0% females), 5,878 (31.9%) died during follow-up. At baseline (2004), 41.6% reported experiencing at least one insomnia symptom. Respondents who experienced one (HR=1.11; 95% CI: 1.03–1.20), two (HR=1.12; 95% CI: 1.01–1.23), three (HR=1.15; 95% CI: 1.05–1.27), or four (HR=1.32; 95% CI: 1.12–1.56) insomnia symptoms had on average a higher hazard of all-cause mortality, compared to those who were symptom-free. For each insomnia symptom, respondents who experienced difficulty initiating sleep (HR=1.12; 95% CI: 1.02–1.22), early-morning awakening (HR=1.09; 95% CI: 1.01–1.18), and nonrestorative sleep (HR=1.17; 95% CI: 1.09–1.26), had a higher hazard of all-cause mortality compared to those not experiencing the symptom. The findings demonstrate significant associations between insomnia symptoms and all-cause mortality, both on a cumulative scale and independently, except for difficulty maintaining sleep. Further research should investigate the underlying mechanisms linking insomnia symptoms and mortality.

Sleep Quality, Insomnia Symptoms, and Depressive Symptomatology among Italian University Students before and during the Covid-19 Lockdown

The COVID-19 pandemic led world authorities to adopt extraordinary measures to counteract the spread of the virus. The Italian government established a national lockdown from 9 March to 3 May 2020, forcing people in their homes and imposing social distancing. During the pandemic emergency, university students emerged as a vulnerable category. Indeed, higher rates of sleep problems and mental disorders were reported in this population. However, these outcomes were derived from cross-sectional investigations adopting retrospective assessments. Retrospective evaluations suffer from different biases, putatively leading to erroneous outcomes. To overcome this limitation, we adopted a between-subject approach comparing a sample of 240 Italian undergraduate university students assessed in 2016 (mean age ± standard deviation, 20.39 ± 1.42, range 18–25; 80.42% females), with an age/gender-matched sample of university students assessed during the third week of lockdown in Spring 2020. We evaluated sleep quality, insomnia symptoms, and depressive symptomatology using validated questionnaires. We found worse sleep quality, a delayed bedtime, and more severe insomnia and depression symptoms in the students sampled under COVID-19 restrictive measures. We suggest paying special attention to this at-risk population during the current pandemic emergency and applying preventive and supportive interventions to limit the exacerbation of sleep and psychological problems.

Association of Subjective Quality and Quantity of Sleep with Quality of Life among a General Population

This study aimed to determine whether both subjective sleep quality and sleep duration are directly associated with quality of life (QOL), as well as indirectly associated with QOL through insomnia symptoms. Individuals aged 20–69 years without mental illness (n = 9305) were enrolled in this web-based cross-sectional survey. The Short Form-8 was used to assess physical and mental QOL. We used the Pittsburgh Sleep Quality Index (PSQI) and extracted items related to subjective sleep quality and sleep duration. Insomnia symptoms were also extracted from the PSQI. The hypothesized models were tested using structural equation modeling. Worse sleep quality, but not shorter sleep duration, was related to worse physical QOL. Both worse sleep quality and shorter sleep duration were related to worse mental QOL. Insomnia symptoms mediated these relationships. Subgroup analyses revealed a U-shaped relationship between sleep duration and physical/mental QOL. However, the relationship between sleep quality and physical/mental QOL was consistent regardless of sleep duration. The results suggest that subjective sleep quality has a more coherent association with QOL than subjective sleep duration. Because of its high feasibility, a questionnaire on overall sleep quality could be a useful indicator in future epidemiological studies of strategies for improving QOL.

Time-Varying Insomnia Symptoms and Incidence of Cognitive Impairment and Dementia among Older US Adults

There is conflicting evidence regarding the association between insomnia and the onset of mild cognitive impairment (MCI) or dementia. This study aimed to evaluate if time-varying insomnia is associated with the development of MCI and dementia. Data from the Health and Retirement Study (n = 13,833) from 2002 to 2014 were used (59.4% female). The Brief Insomnia Questionnaire was used to identify insomnia symptoms compiled in an insomnia severity index, ranging from 0 to 4. In the analysis, participants’ symptoms could vary from wave-to-wave. Dementia was defined using results from the Health and Retirement Study (HRS) global cognitive assessment tool. Respondents were classified as either having dementia, MCI or being cognitively healthy. Cox proportional hazards models with time-dependent exposure using the counting process (start-stop time) were used for analysis. For each one-unit increase in the insomnia symptom index, there was a 5-percent greater hazard of MCI (HR = 1.05; 95% CI: 1.04–1.06) and dementia (HR = 1.05; 95% CI: 1.03–1.05), after fully adjusting. Using a nationally representative sample of adults aged 51 and older, this study found that time-varying insomnia symptoms are associated with the risk of MCI and dementia. This highlights the importance of identifying sleep disturbances and their change over time as potentially important risk factors for MCI and dementia.

Stress, Cognition, and Minority Health

This symposium examines the many factors influencing cognition and health among ethnically and racially diverse groups. Kindratt et al. use representative, national data to examine cognitive limitations and diabetes among foreign born Non-Hispanic Whites, Blacks, Hispanics, Asians and Arab Americans. Results indicate that prevalence of cognitive limitations was highest among non-Hispanic Whites and Arab-Americans, lowest among Blacks and Asians. Diminich et al. investigate the association of stressors and metabolic risk factors with cognitive/emotional functioning in a population of Hispanic/Latina(o) immigrants. They find a link between components of metabolic syndrome that are associated with domain specific deficits in cognition. These impairments are linked to posttraumatic stress, immigration related trauma and emotional health and wellbeing. Arevalo et al. examine cross-sectional and prospective associations of sleep duration and insomnia symptoms with measures of cognitive functioning among older Latinos from Puerto Rican ancestry with a longitudinal sample of older adults from the Boston Puerto Rican Health Study. Findings indicate that hours of sleep and insomnia symptoms are significantly associated with a number of global and specific cognitive factors. Finally, Munoz and colleagues, using a regional racially and ethnically diverse sample of people living in a large northeastern city, identified four stress profiles. These profiles (which focus on different types of stress) were differentially associated with working memory performance. In sum, these four papers document the experiences of stress and their association with cognitive functioning in diverse minority groups each of whom are disproportionately at risk for ADRD/RD. Gerald, from NIA, will serve as discussant.

Sleep and Cognition: Results From a Longitudinal Cohort of Older Puerto Rican Adults

We examined cross-sectional and prospective associations of sleep duration and insomnia symptoms with measures of cognitive function among older adults aged 45-75 y from the Boston Puerto Rican Health Study, a longitudinal cohort of 1500 participants of Puerto Rican ancestry. We found, statistically significant cross-sectional associations of sleep duration (hours) and an executive function domain before (F=6.20; Prob>F=0.0001) and after (F=2.33; Prob>F=0.05) controlling for covariates (age, sex, education, smoking, drinking, mental and health conditions and medication use); between sleep duration and global cognition before (F=5.38; Prob>F=0.0003) and a trend after controlling for covariates (F=2.20; Prob>F=0.0669). In longitudinal associations, sleep duration (time2) was significantly associated with global condition at time3 (F=2.42; Prob>F=0.0475) after controlling for time2 global cognition. In conclusion, we found hours of sleep and insomnia symptoms significantly associated with various cognitive factors. A public health focus on sleep hygiene may improve cognitive health outcomes in older Puerto Rican adults.

IgLON5 autoimmunity tested positive in patients with isolated chronic insomnia disease

In the patients with neurological autoimmune diseases such as anti-IgLON5 disease, insomnia symptoms are very common. Clinical diagnosis of the anti-IgLON5 disease is usually made when neurodegenerative processes have occurred. To find the early signs of anti-IgLON5 disease, we evaluate the presence of IgLON5 autoantibodies in the serum of patients with chronic insomnia disease. Based on video-polysomnography, twenty-two individuals with isolated chronic insomnia disease were found. A control group of twenty-two healthy people was chosen using the PSQI. An indirect immunofluorescence cell-based test of serum anti-IgLON5 antibodies was used to investigate IgLON5 autoimmunity. Anti-IgLON5 antibodies were detected in the serum of four of these patients with the titer of 1/10. The presence of IgLON5 autoantibodies in some patients with chronic insomnia disease can be considered a causing factor of insomnia which can be effective in more specific treatments of these patients. Moreover, the recognition of anti-IgLON5 disease in the early stages and before the progression of tauopathies can be useful in effective and timely treatment.