Sleep duration and all-cause mortality among stroke survivors.

BACKGROUND: Post stroke sleep duration could increase the risk of death. This study tested the hypothesis that inadequate sleep duration is associated with increased mortality among stroke survivors. METHODS: The REasons for Geographic And Racial Differences in Stroke (REGARDS), a national population-based longitudinal study, was the data source. Sleep duration was ascertained between 2013 and 2016 among stroke survivors who were subsequently followed up until death or censored on December 31, 2022. Sleep duration was estimated as the difference between wake-up time and bedtime to which was subtracted the time spent in bed without sleep. Cox proportional hazards regression models were employed to investigate the association between sleep duration and all-cause mortality adjusting for demographic factors, socioeconomic factors, behavioral factors, and co-morbidities. RESULTS: A total of 468 non-Hispanic Black and White stroke survivors were included in this analysis. The mean age was 76.3 years, 52.6% were females and 56.0% were non-Hispanic White individuals. The distribution of short (≤6 h), adequate (7.0-8.9 h), and long sleep (≥9 h) was 30.3%, 44.7%, and 25%, respectively. Over a mean follow-up of 5.0 years, 190 (40.6%) deaths occurred. Compared to stroke survivors with adequate sleep (7.0-8.9 h), stroke survivors with long sleep (≥9 h) were at increased risk of all-cause mortality (HR=1.46, 95% CI=1.01, 2.12). However, short sleep (≤6 h) was not significantly associated with an increased risk of all-cause mortality (HR=1.31, 95% CI=0.90, 1.91). Subgroup analyses indicated higher risk in the age <75 years, females, non-Hispanic Black individuals, and those living in the Stroke Belt region, but those differences were not statistically significant. CONCLUSION: In this study of stroke survivors, 9 hours or more of sleep per day was associated with an increased risk of all-cause mortality. This finding suggests that excessive sleep duration may be a warning sign of poor life expectancy in stroke survivors.

Three-Dimensional Energy Transfer in Space Plasma Turbulence from Multipoint Measurement.

A novel multispacecraft technique applied to Magnetospheric Multiscale Mission data in the Earth's magnetosheath enables evaluation of the energy cascade rate from the full Yaglom's equation. The method differs from existing approaches in that it (i) is inherently three-dimensional, (ii) provides a statistically significant number of estimates from a single data stream, and (iii) allows visualization of energy flux in turbulent plasmas. This new "lag polyhedral derivative ensemble" technique exploits ensembles of tetrahedra in lag space and established curlometerlike algorithms.

Longitudinal and cross-sectional associations between the dietary inflammatory index and objectively and subjectively measured sleep among police officers.

Police officers experience exposures associated with increased inflammation, such as the stress associated with shiftwork and poor-quality diet, both of which have been shown to affect sleep duration and quality. This study examined the longitudinal and cross-sectional effects of the Energy-density Dietary Inflammatory Index (E-DII™) on objectively and subjectively measured sleep among police officers. Data were derived from the Buffalo Cardio-Metabolic Occupational Police Stress Cohort (n = 464 at baseline), with longitudinal data collected from 2004 to 2019. A food frequency questionnaire obtained estimated dietary intake from which E-DII scores were calculated. Dependent variables were objectively (Micro Motion Logger Sleep Watch™) and subjectively (Pittsburgh Sleep Quality Index) measured sleep quality and quantity. The analyses included a series of linear mixed-effects models used to examine cross-sectional and longitudinal associations between the E-DII and sleep quantity and quality. Cross-sectionally, more pro-inflammatory diets were associated with higher wake-after-sleep-onset but improved subjective sleep quality. In models accounting for both longitudinal and cross-sectional effects, for every 1-unit increase in the E-DII scores over time (representing a pro-inflammatory change), wake-after-sleep-onset increased by nearly 1.4 min (p = 0.07). This result was driven by officers who primarily worked day shifts (ß = 3.33, p = 0.01). Conversely, for every 1-unit increase in E-DII score, the Pittsburgh Sleep Quality Index global score improved. More pro-inflammatory diets were associated with increased wake-after-sleep-onset, an objective measure of sleep quality. Intervention studies to reduce dietary inflammatory potential may provide greater magnitude of effect for changes in sleep quality.

Statistics of Kinetic Dissipation in the Earth's Magnetosheath: MMS Observations.

A familiar problem in space and astrophysical plasmas is to understand how dissipation and heating occurs. These effects are often attributed to the cascade of broadband turbulence which transports energy from large scale reservoirs to small scale kinetic degrees of freedom. When collisions are infrequent, local thermodynamic equilibrium is not established. In this case the final stage of energy conversion becomes more complex than in the fluid case, and both pressure-dilatation and pressure strain interactions (Pi-D≡-Π_{ij}D_{ij}) become relevant and potentially important. Pi-D in plasma turbulence has been studied so far primarily using simulations. The present study provides a statistical analysis of Pi-D in the Earth's magnetosheath using the unique measurement capabilities of the Magnetospheric Multiscale (MMS) mission. We find that the statistics of Pi-D in this naturally occurring plasma environment exhibit strong resemblance to previously established fully kinetic simulations results. The conversion of energy is concentrated in space and occurs near intense current sheets, but not within them. This supports recent suggestions that the chain of energy transfer channels involves regional, rather than pointwise, correlations.

In Situ Observation of Hall Magnetohydrodynamic Cascade in Space Plasma.

We present estimates of the turbulent energy-cascade rate derived from a Hall-magnetohydrodynamic (MHD) third-order law. We compute the contribution from the Hall term and the MHD term to the energy flux. Magnetospheric Multiscale (MMS) data accumulated in the magnetosheath and the solar wind are compared with previously established simulation results. Consistent with the simulations, we find that at large (MHD) scales, the MMS observations exhibit a clear inertial range dominated by the MHD flux. In the subion range, the cascade continues at a diminished level via the Hall term, and the change becomes more pronounced as the plasma beta increases. Additionally, the MHD contribution to interscale energy transfer remains important at smaller scales than previously thought. Possible reasons are offered for this unanticipated result.

High-Frequency Waves Driven by Agyrotropic Electrons Near the Electron Diffusion Region.

National Aeronautics and Space Administration's Magnetosphere Multiscale mission reveals that agyrotropic electrons and intense waves are prevalently present in the electron diffusion region. Prompted by two distinct Magnetosphere Multiscale observations, this letter investigates by theoretical means and the properties of agyrotropic electron beam-plasma instability and explains the origin of different structures in the wave spectra. The difference is owing to the fact that in one instance, a continuous beam mode is excited, while in the other, discrete Bernstein modes are excited, and the excitation of one mode versus the other depends on physical input parameters, which are consistent with observations. Analyses of dispersion relations show that the growing mode becomes discrete when the maximum growth rate is lower than the electron cyclotron frequency. Making use of particle-in-cell simulations, we found that the broadening angle Δ in the gyroangle space is also an important factor controlling the growth rate. Ramifications of the present finding are also discussed.

The Effects of Upper-Hybrid Waves on Energy Dissipation in the Electron Diffusion Region.

Using a two-dimensional particle-in-cell simulation, we investigate the effects and roles of upper-hybrid waves (UHW) near the electron diffusion region (EDR). The energy dissipation via the wave-particle interaction in our simulation agrees with J · E ' measured by magnetospheric multiscale (MMS) spacecraft. It means that UHW contributes to the local energy dissipation. As a result of wave-particle interactions, plasma parameters which determine the larger-scale energy dissipation in the EDR are changed. The y-directional current decreases while the pressure tensor P y z increases/decreases when the agyrotropic beam density is low/high, where (x, y, z)-coordinates correspond the (L, M, N)-boundary coordinates. Because the reconnection electric field comes from -∂ P y z /∂ z, our result implies that UHW plays an additional role in affecting larger-scale energy dissipation in the EDR by changing plasma parameters. We provide a simple diagram that shows how the UHW activities change the profiles of plasma parameters near the EDR comparing cases with and without UHW.

Symptom Management Among Cancer Survivors: Randomized Pilot Intervention Trial of Heart Rate Variability Biofeedback.

Chronic cancer-related symptoms (stress, fatigue, pain, depression, insomnia) may be linked with sympathetic nervous system over-activation and autonomic imbalance. Decreased heart rate variability (HRV) is an indicator of autonomic dysregulation that is commonly observed among cancer survivors. HRV biofeedback (HRVB) training induces HRV coherence, which maximizes HRV and facilitates autonomic and cardiorespiratory homeostasis. This randomized, wait-list-controlled, pilot intervention trial tested the hypothesis that HRVB can improve HRV coherence and alleviate cancer-related symptoms. The intervention group (n = 17) received 4-6 weekly HRVB training sessions until participants demonstrated skill acquisition. Controls (n = 17) received usual care. Outcomes assessed at baseline and follow-up included 15-min HRV recordings (HRV Coherence Ratio), and symptoms of: stress, distress, post-traumatic stress disorder (PTSD), pain, depression, fatigue, and sleep disturbance. Linear mixed models for repeated measures were used to assess Group-by-Time interactions, pre- versus post-treatment differences in mean symptom scores, and group differences at follow-up. Mean HRV Coherence Ratios (± standard error) improved in the HRVB group at follow-up (baseline: 0.37 ± 0.05, post-intervention: 0.84 ± 0.18, p = 0.01), indicating intervention validity. Statistically significant Group-by-Time interactions indicated treatment-related improvements in HRV Coherence Ratios (p = 0.03, Pre-vs. post-treatment effect size [Cohen's d]: 0.98), sleep symptoms (p = 0.001, d = 1.19), and sleep-related daytime impairment (p = 0.005, d = 0.86). Relative to controls, the intervention group experienced trends toward improvements in stress, distress, fatigue, PTSD, and depression, although no other statistically significant Group-by-Time interactions were observed. This pilot intervention found that HRVB training reduced symptoms of sleep disturbance among cancer survivors. Larger-scale interventions are warranted to further evaluate the role of HRVB for managing symptoms in this population. Registration: NCT03692624 www.clinicaltrials.gov.

High-Frequency Wave Generation in Magnetotail Reconnection: Nonlinear Harmonics of Upper Hybrid Waves.

MMS3 spacecraft passed the vicinity of the electron diffusion region of magnetotail reconnection on 3 July 2017, observing discrepancies between perpendicular electron bulk velocities and E → × B → drift, and agyrotropic electron crescent distributions. Analyzing linear wave dispersions, Burch et al. (2019, https://doi.org/10.1029/2019GL082471) showed the electron crescent generates high-frequency waves. We investigate harmonics of upper-hybrid (UH) waves using both observation and particle-in-cell (PIC) simulation, and the generation of electromagnetic radiation from PIC simulation. Harmonics of UH are linearly polarized and propagate along the perpendicular direction to the ambient magnetic field. Compared with two-dimensional PIC simulation and nonlinear kinetic theory, we show that the nonlinear beam-plasma interaction between the agyrotropic electrons and the core electrons generates harmonics of UH. Moreover, PIC simulation shows that agyrotropic electron beam can lead to electromagnetic (EM) radiation at the plasma frequency and harmonics.

Shift Work and Heart Rate Variability Coherence: Pilot Study Among Nurses.

This study used ambient heart rate monitoring among health care workers to determine whether a novel measure of heart rate variability (HRV), as well as sleep disturbances, fatigue, or cognitive performance differed among non-rotating night shift nurses relative to those working permanent day shifts. Continuous ambulatory HRV monitoring was performed among night nurses (n = 11), and a comparison group of permanent day nurses (n = 7), over a 36-h period coinciding with the last two 12-h shifts of each participant's work week. Symptoms and psychomotor vigilance were assessed at the end of the ambient HRV monitoring period, and no differences between shifts were observed. Day nurses exhibited an increase in hourly mean HRV coherence ratios during their sleep period, suggesting a circadian pattern of cardiorespiratory phase coupling, whereas night nurses had no increase in HRV coherence ratios during their sleep period. The HRV coherence patterns were similar to high frequency HRV power among nurses on the same shift. To the authors knowledge, this study was the first to quantify patterns of the HRV coherence ratio among shiftworkers in a non-experimental (work/home) setting. The results suggest a pattern of autonomic dysregulation among night workers during their sleep period relative to those working day shifts. The HRV coherence ratio may serve as a novel indicator of HRV dysregulation among shift workers.

A healthy lifestyle index is associated with reduced risk of colorectal adenomatous polyps among non-users of non-steroidal anti-inflammatory drugs.

In a Columbia, South Carolina-based case-control study, we developed a healthy lifestyle index from five modifiable lifestyle factors (smoking, alcohol intake, physical activity, diet, and body mass index), and examined the association between this lifestyle index and the risk of colorectal adenomatous polyps (adenoma). Participants were recruited from a local endoscopy center and completed questionnaires related to lifestyle behaviors prior to colonoscopy. We scored responses on each of five lifestyle factors as unhealthy (0 point) or healthy (1 point) based on current evidence and recommendations. We added the five scores to produce a combined lifestyle index for each participant ranging from 0 (least healthy) to 5 (healthiest), which was dichotomized into unhealthy (0-2) and healthy (3-5) lifestyle scores. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) for adenoma with adjustment for multiple covariates. We identified 47 adenoma cases and 91 controls. In the main analyses, there was a statistically nonsignificant inverse association between the dichotomous (OR 0.54; 95% CI 0.22, 1.29) and continuous (OR 0.75; 95% CI 0.51, 1.10) lifestyle index and adenoma. Odds of adenoma were significantly modified by the use of non-steroidal anti-inflammatory drugs (NSAIDs) (p(interaction) = 0.04). For participants who reported no use of NSAIDs, those in the healthy lifestyle category had a 72% lower odds of adenoma as compared to those in the unhealthy category (OR 0.28; 95% CI 0.08, 0.98), whereas a one-unit increase in the index significantly reduced odds of adenoma by 53% (OR 0.47; 95% CI 0.26, 0.88). Although these findings should be interpreted cautiously given our small sample size, our results suggest that higher scores from this index are associated with reduced odds of adenomas, especially in non-users of NSAIDs. Lifestyle interventions are required to test this approach as a strategy to prevent colorectal adenomatous polyps.

Case-control study of breast cancer in India: Role of PERIOD3 clock gene length polymorphism and chronotype.

BACKGROUND: This study examined a PERIOD3 (PER3) gene variable number tandem repeat polymorphism and chronotype as potential BrCA risk factors among Indian women. METHODS: This case-control study included sporadic, histologically confirmed BrCA cases (n = 255) and controls (n = 249) from India with data collection from 2010-2012. RESULTS: Women with the 4/5 or 5/5 PER3 genotype had a nonstatistically significant 33% increased odds of BrCA. Cases were more likely to have a morning (OR = 2.43, 95% CI = 1.23-4.81) or evening (OR = 2.55, 95% CI = 1.19-5.47) chronotype. CONCLUSIONS: Findings are consistent with the possibility that extremes in chronotype may elicit circadian desynchronization, resulting in increased BrCA susceptibility.

Mercury in fish and adverse reproductive outcomes: results from South Carolina.

BACKGROUND: Mercury is a metal with widespread distribution in aquatic ecosystems and significant neurodevelopmental toxicity in humans. Fish biomonitoring for total mercury has been conducted in South Carolina (SC) since 1976, and consumption advisories have been posted for many SC waterways. However, there is limited information on the potential reproductive impacts of mercury due to recreational or subsistence fish consumption. METHODS: To address this issue, geocoded residential locations for live births from the Vital Statistics Registry (1995-2005, N = 362,625) were linked with spatially interpolated total mercury concentrations in fish to estimate potential mercury exposure from consumption of locally caught fish. Generalized estimating equations were used to test the hypothesis that risk of low birth weight (LBW, <2,500 grams) or preterm birth (PTB, < 37 weeks clinical gestation) was greater among women living in areas with elevated total mercury in fish, after adjustment for confounding. Separate analyses estimated term LBW and PTB risks using residential proximity to rivers with fish consumption advisories to characterize exposure. RESULTS: Term LBW was more likely among women residing in areas in the upper quartile of predicted total mercury in fish (odds ratio [OR] = 1.04; 95% confidence interval [CI]: 1.00-1.09) or within 8 kilometers of a river with a 'do not eat' fish advisory (1.05; 1.00-1.11) compared to the lowest quartile, or rivers without fish consumption restrictions, respectively. When stratified by race, risks for term LBW or PTB were 10-18% more likely among African-American (AA) mothers living in areas with the highest total fish mercury concentrations. CONCLUSIONS: To our knowledge, this is the first study to examine the relationship between fish total mercury concentrations and adverse reproductive outcomes in a large population-based sample that included AA women. The ecologic nature of exposure assessment in this study precludes causal inference. However, the results suggest a need for more detailed investigations to characterize patterns of local fish consumption and potential dose-response relationships between mercury exposure and adverse reproductive outcomes, particularly among AA mothers.

Cancer Prevention Among Firefighters: Examining Lifestyle, Screening Behavior, and Beliefs.

BACKGROUND: Firefighters are at increased risk of developing cancer due to occupational exposures, but they may also face increased risk due to their lifestyle, such as the quality of their diet and physical activity. Cancer beliefs and screening behavior could also influence their cancer risk. The current study aimed to identify individual differences associated with lifestyle behaviors, cancer screening, and cancer beliefs among firefighters; to describe the strategies firefighters use to adapt to their work schedule; and to describe topics firefighters believe are the most important to address in their workplace. METHODS: Career firefighters (N = 171) in a medium-sized U.S. city completed an online survey. FINDINGS: Logistic regression analyses identified age, education, racial identity, years of fire service, perceived stress, and rank as predictors of responses to items addressing cancer screening, lifestyle behaviors, and cancer beliefs. Although results varied, age, education, and racial identity were associated with most of the outcomes. Strategies related to sleep such as getting the right amount and napping, exercise, and getting family/roommate support were selected as the top adaptive strategies for work. Sleep, mental health/well-being, and work-life balance were selected most often as the most important topics to address in the fire service, with topics related to reducing occupational exposures receiving less attention. CONCLUSIONS/APPLICATION TO PRACTICE: The findings suggest individual differences, such as age, education, and racial identity, should be considered when developing occupational health interventions for firefighters. Interventions related to mental health, work-life balance, and sleep may be desired most by those in the fire service.

Sleep disorders and cancer incidence: examining duration and severity of diagnosis among veterans.

Introduction: Sleep disruption affects biological processes that facilitate carcinogenesis. This retrospective cohort study used de-identified data from the Veterans Administration (VA) electronic medical record system to test the hypothesis that patients with diagnosed sleep disorders had an increased risk of prostate, breast, colorectal, or other cancers (1999-2010, N=663,869). This study builds upon existing evidence by examining whether patients with more severe or longer-duration diagnoses were at a greater risk of these cancers relative to those with a less severe or shorter duration sleep disorder. Methods: Incident cancer cases were identified in the VA Tumor Registry and sleep disorders were defined by International Classification of Sleep Disorder codes. Analyses were performed using extended Cox regression with sleep disorder diagnosis as a time-varying covariate. Results: Sleep disorders were present among 56,055 eligible patients (8% of the study population); sleep apnea (46%) and insomnia (40%) were the most common diagnoses. There were 18,181 cancer diagnoses (41% prostate, 12% colorectal, 1% female breast, 46% other). The hazard ratio (HR) for a cancer diagnosis was 1.45 (95% confidence interval [CI]: 1.37, 1.54) among those with any sleep disorder, after adjustment for age, sex, state of residence, and marital status. Risks increased with increasing sleep disorder duration (short [<1-2 years] HR: 1.04 [CI: 1.03-1.06], medium [>2-5 years] 1.23 [1.16-1.32]; long [>5-12 years] 1.52 [1.34-1.73]). Risks also increased with increasing sleep disorder severity using cumulative sleep disorder treatments as a surrogate exposure; African Americans with more severe disorders had greater risks relative to those with fewer treatments and other race groups. Results among patients with only sleep apnea, insomnia, or another sleep disorder were similar to those for all sleep disorders combined. Discussion: The findings are consistent with other studies indicating that sleep disruption is a cancer risk factor. Optimal sleep and appropriate sleep disorder management are modifiable risk factors that may facilitate cancer prevention.

Disease progression and characteristics of HIV-infected women with and without a history of criminal justice involvement.

Early HIV diagnosis followed by prompt linkage to and consistent retention in HIV-related care is important to decrease morbidity and mortality. Progression to AIDS is of particular interest in HIV-positive women with a history of criminal justice-involvement due to their lack of access to care in the community and poor retention in HIV primary care. In this retrospective cohort study, we characterize the risk of developing AIDS among HIV-infected women with and without a history of criminal justice-involvement. Mean time to AIDS diagnosis was longer [123 ± 3.26 months] for women with no criminal justice-involvement when compared to women who were arrested or who went to prison. Women who were arrested (HR: 1.92, 95% CI: 1.43, 2.58) and women who went to prison (HR: 2.27, 95% CI: 1.52, 3.39) had an increased risk of developing AIDS when compared to women without criminal justice-involvement.

The epidemiology of cancer among police officers.

BACKGROUND: This review summarizes peer-reviewed studies examining cancer risks among police officers. It provides an overview of existing research limitations and uncertainties and the plausible etiologic risk factors associated with cancer in this understudied occupation. METHODS: Previous cancer studies among police officers were obtained via a systematic review of the MEDLINE, CABDirect, and Web of Science bibliographic databases. RESULTS: Quality observational studies of cancer among police officers are sparse and subject to limitations in exposure assessment and other methods. Results from three studies suggested possible increased mortality risks for all cancers, and cancers of the colon, kidney, digestive system, esophagus, male breast, and testis, as well as Hodgkin's disease. Few incidence studies have been performed, and results have been mixed, although some associations with police work have been observed for thyroid, skin, and male breast cancer. CONCLUSIONS: Police are exposed to a mix of known or suspected agents or activities that increase cancer risk. Epidemiologic evidence to date is sparse and inconsistent. There is a critical need for more research to understand the biological and social processes underlying exposures and the suggested disproportionate risks and to identify effective prevention strategies.

Association of the Period3 clock gene length polymorphism with salivary cortisol secretion among police officers.

OBJECTIVE: This study evaluated whether measures of waking or diurnal cortisol secretion, or self-reported psychological disturbances differed among police officers with a Period3 (PER3) clock gene length polymorphism. METHODS: The cortisol awakening response was characterized via the area under the salivary cortisol curve with respect to the increase (AUCI) or total waking cortisol (AUCG). Diurnal cortisol measures included the slope of diurnal cortisol and the diurnal AUCG. Psychological disturbances were characterized using the Center for Epidemiologic Studies Depression Scale, Impact of Events Scale, and Life Events Scale. RESULTS: Officers with a 4/5 or 5/5 genotype had higher awakening AUCG and greater diurnal cortisol AUCG levels compared to officers with the 4/4 genotype. Among those working more afternoon or night shifts, waking AUCI and AUCG were greater among officers with a 4/5 or 5/5 genotype compared to the 4/4 referents. CONCLUSION: Cortisol secretion was modified among police officers with different PER3 VNTR clock gene variants.

Association Between Insomnia Symptoms and Trajectory With the Risk of Stroke in the Health and Retirement Study.

BACKGROUND AND OBJECTIVES: Insomnia is a common condition affecting more than a third of the US population. However, the link between insomnia symptoms and stroke is understudied and the underlying mechanism remains unclear. This study aimed to investigate the relationship between insomnia symptoms and the incidence of stroke. METHODS: The Health and Retirement Study, a survey of Americans older than 50 years and their spouses, from 2002 to 2020 was used as the data source. Only those who were stroke-free at baseline were included in this study. The exposure variable was insomnia symptoms and was derived from self-reported sleep-related factors including difficulty initiating sleep, difficulty maintaining sleep, waking up too early, and nonrestorative sleep. Repeated-measures latent class analysis was used to identify insomnia trajectories over time. To investigate the relationship between insomnia symptoms and stroke events reported during the follow-up period, Cox proportional hazards regression models were used. Mediation analyses of comorbidities were performed using causal mediation within a counterfactual framework. RESULTS: A total of 31,126 participants were included with a mean follow-up of 9 years. The mean age was 61 years (SD = 11.1) and 57% were females. Insomnia symptom trajectories remained constant over time. Compared with those with no insomnia symptoms, an increased risk of stroke was observed for those with insomnia symptom scores ranging from 1 to 4 and 5 to 8 (hazard ratio (HR) = 1.16, 95% confidence interval (CI) 1.02-1.33) and (HR = 1.51, 95% CI 1.29-1.77), respectively, indicating a dose-response relationship. The association was stronger in participants younger than 50 years (HR = 3.84, 95% CI 1.50-9.85) than in those aged 50 years and older (HR = 1.38, 95% CI 1.18-1.62), comparing those with insomnia symptoms ranging from 5 to 8 with those with no insomnia symptoms. This association was mediated by diabetes, hypertension, heart disease, and depression. DISCUSSION: Insomnia symptoms were associated with an increased risk of stroke, especially in adults younger than 50 years, and the risk was mediated by certain comorbidities. Increased awareness and management of insomnia symptoms may contribute to the prevention of stroke occurrence.

The role of sleep and heart rate variability in metabolic syndrome: evidence from the Midlife in the United States study.

STUDY OBJECTIVES: Poor sleep and autonomic dysregulation can both disrupt metabolic processes. This study examined the individual and combined effects of poor sleep and reduced heart rate variability (HRV) on metabolic syndrome among 966 participants in the Midlife in the United States II (MIDUS II) study. METHODS: Self-reported sleep was assessed using the Pittsburgh Sleep Quality Index (PSQI). HRV was acquired from 11-minute resting heart rate recordings. Spearman correlations, general linear regression, and logistic regression models were used to examine the study hypotheses. RESULTS: Poor sleep quality was associated with metabolic syndrome when global PSQI scores were evaluated as a continuous (odds ratio [OR]: 1.07, 95% confidence interval [CI]: 1.03 to 1.11) or categorical measure (cutoff > 5, OR: 1.58, 95% CI: 1.19 to 2.10), after adjustment for confounding. There also was an association between reduced HRV and metabolic syndrome (ln [HF-HRV] OR: 0.89, 95% CI: 0.80 to 0.99; ln [LF-HRV] OR: 0.82, 95% CI: 0.72 to 0.92; ln [SDRR] OR: 0.59, 95% CI: 0.43 to 0.79; ln [RMSSD] OR: 0.75, 95% CI: 0.60 to 0.94). When the combined effects of poor sleep and low HRV were examined, the association with metabolic syndrome was further strengthened relative to those with normal sleep and HRV. CONCLUSIONS: To the best of the author's knowledge, this is the first study to suggest a combined effect of poor sleep and low HRV on the odds of metabolic syndrome.