Sleep as a mediator in the pathway linking environmental factors to hypertension: a review of the literature

Neighborhood Stress Predicts Fear of Sleep Independently of Posttraumatic Stress Disorder

BACKGROUND

Chronic insufficient sleep is linked to a variety of adverse health outcomes, and African Americans have been found to have poorer sleep than their non-Hispanic White counterparts. African Americans disproportionately live in low-income disordered neighborhoods which increases their risk of trauma exposure and adversely affects their sleep. Fear of sleep is a construct linked to posttraumatic stress disorder (PTSD). We have reported a relationship between fear of sleep and insomnia in urban residing African Americans. Our objective is to report the relative contributions of neighborhood stress along with PTSD to fear of sleep.

METHODS

The present study features a nonclinical sample of 117 African Americans (ages 18-35) who reside in DC.

RESULTS

After controlling for gender, hierarchical linear regression analyses revealed that PTSD severity and perceptions of the neighborhood environment accounted for approximately 32% of the variance in sleep-related fears (∆R2 = .320, p < .001). Regression coefficients suggest that perceptions of the neighborhood (β = .360) predict sleep-related fears to a similar degree as PTSD severity (β = .368).

CONCLUSION

Results from this study have implications for interventions to help African Americans to cope with their neighborhood environments effect on their sleep.

Comprehensive review of the current literature on impact of ambient air pollution and sleep quality

Air pollution is associated with increasing morbidity, mortality and decreasing health and life span. Accumulating epidemiological and experimental evidence has shown that exposure to ambient air pollutants such as particulate matters (PM) and gaseous components [eg, nitrogen dioxide (NO₂), ozone (O₃)] has detrimental effects on sleep quality. We conducted this comprehensive review to explore the association between ambient air pollution and sleep quality. A systematic search was conducted with the databases of PubMed and Web of Science from inception to November 2019. Overall, 15 studies with 133,695 subjects that evaluated the association between ambient air pollution and sleep quality were conducted in 10 different countries (ie, USA, Brazil, Canada, Chile, China, Egypt, Germany, Iran, Mexico, and Turkey). Most included studies in the current review have shown that one or more air pollutants have negative influences on sleep quality. Air pollutants might be one of the triggers for poor sleep quality via disparate mechanisms including but not limited to the central ventilator control centers, central nervous system, allergic and non-allergic mechanisms. The possible association between air pollution and select chronic diseases (eg, mental illnesses, cardiovascular diseases) and behaviors (eg, impulsivity) may also play important roles in explaining the association between ambient air pollution and sleep quality. The associations and underlying mechanisms between ambient air pollutants and sleep quality need to be clarified with long-term, multi-centered cohort studies.

The Relationship Between Quality of Sleep and Quality of Life of Patients in Medan, Indonesia

BACKGROUND

Hypertension is one of the most common diseases around the world, which is the most risk factor related to cardiovascular disease. The quality of life of hypertensive patients is influenced by various factors, namely age, sex, educational background, ethnicity and nutritional status. Another factor that is also important is the quality of sleep.

AIM

We aimed the assessment of sleep quality using a PSQI questionnaire, and quality of life assessment with the SF-36 questionnaire.

METHODS

This study was a cross-sectional study of 45 respondents at the H. Adam Malik Central General Hospital in Medan in 2018. Assessment of sleep quality was performed through the PSQI questionnaire (Pittsburgh Sleep Quality Index), and quality of life assessment was carried out with the SF-36 questionnaire.

RESULTS

The prevalence of impaired sleep quality in hypertensive patients was 35.6%. Most patients have a good quality of life, with 71.1%. In this study, sleep quality was found to be related to the quality of life (p = 0.037). Furthermore, variables related to sleep quality were sex (gender) (p = 0.003) and education (p = 0.005). In multivariate analysis, the quality of life is predominantly influenced by sleep quality (p = 0.025).

CONCLUSION

The quality of life of hypertensive patients is influenced by the quality of sleep.

Insufficient sleep is associated with a pro-atherogenic circulating microRNA signature

NEW FINDINGS

What is the central question of the study Is habitual short sleep associated with altered circulating levels of specific inflammation- and vascular-related microRNAs? What is the main finding and its importance? Circulating levels of miR-125a, miR-126 and miR-146a were significantly lower in the short sleep compared with the normal sleep group. Altered circulating profiles of these vascular-related microRNAs have been linked to vascular inflammation, dysfunction and increased cardiovascular disease events. Sleep-related changes in these microRNAs are consistent with, and might play a role in, the aberrant vascular physiology and increased vascular risk associated with short sleep.

ABSTRACT

Habitual short sleep duration (<7 h night^-1 ) is associated with increased morbidity and mortality attributable, in large part, to increased inflammatory burden and endothelial dysfunction. MicroRNAs (miRNAs) play a key role in regulating vascular health, and circulating levels are now recognized to be sensitive and specific biomarkers of cardiovascular function, inflammation and disease.  The aim of this study was to determine whether the expression of circulating miR-34a, miR-92a, miR-125a, miR-126, miR-145, miR-146a and miR-150 is disrupted in adults who habitually sleep <7 h night^-1 (short sleep). These were chosen based upon their well-established links with vascular inflammation, function and, in turn, cardiovascular risk. Twenty-four adults were studied: 12 with normal nightly sleep duration (six men and six women; age, 55 ± 3 years old; sleep duration, ≥7.0 h night^-1 ) and 12 with short nightly sleep duration (seven men and five women; 55 ± 2 years old; sleep duration, <7 h night^-1 ), and circulating miRNA expression was assayed by RT-PCR. All subjects were non-smokers, normolipidaemic, non-medicated and free of overt cardiovascular disease. Circulating levels of miR-125a (3.07 ± 1.98 versus 7.34 ± 5.34 a.u.), miR-126 [1.28 (0.42-2.51) versus 1.78 (1.29-4.80) a.u.] and miR-146a [2.55 (1.00-4.80) versus 6.46 (1.50-11.44) a.u.] were significantly lower (∼60, 40 and 60%, respectively) in the short compared with the normal sleep group. However, there were no significant group differences in circulating levels of miR-34a, miR-92a, miR-145 and miR-150. In summary, chronic short sleep is associated with a marked reduction in circulating levels of miR-125a, miR-126 and miR-146a. Dysregulation of these miRNAs might contribute to the increased inflammatory burden and endothelial dysfunction associated with habitual insufficient sleep.

Controversies in the 2017 ACC/AHA Hypertension Guidelines: Who Can Be Eligible for Treatments Under the New Guidelines? - An Asian Perspective

Until the 2017 ACC/AHA Hypertension Guidelines were released, the target blood pressure (BP) for adults with hypertension (HTN) was 140/90 mmHg in most of the guidelines. The new 2018 ESC/ESH, Canadian, Korean, Japan, and Latin American hypertension guidelines have maintained the <140/90 mmHg for the primary target in the general population and encourage reduction to <130/80 if higher risk. This is more in keeping with the 2018 American Diabetes Association guidelines. However, the 2017 ACC/AHA guidelines classify HTN as BP ≥130/80 mmHg and generally recommend target BP levels below 130/80 mmHg for hypertensive patients independently of comorbid disease or age. Although the new guidelines mean that more people (nearly 50% of adults) will be diagnosed with HTN, the cornerstone of therapy is still lifestyle management unless BP cannot be lowered to this level; thus, more people will require BP-lowering medications. To date, there have been many controversies about the definition of HTN and the target BP. Targeting an intensive systolic BP goal can increase the adverse effects of multiple medications and the cardiovascular disease risk by excessively lowering diastolic BP, especially in patients with high risk, including those with diabetes, chronic kidney disease, heart failure, and coronary artery disease, and the elderly. In this review, we discuss these issues, particularly regarding the optimal target BP.

Echoes from Gaea, Poseidon, Hephaestus, and Prometheus: environmental risk factors for high blood pressure

High blood pressure (BP) affects over one billion people and is the leading risk factor for global mortality. While many lifestyle and genetic risk factors are well-accepted to increase BP, the role of the external environment is typically overlooked. Mounting evidence now supports that numerous environmental factors can promote an elevation in BP. Broadly speaking these include aspects of the natural environment (e.g., cold temperatures, higher altitude, and winter season), natural disasters (e.g., earthquakes, volcanic eruptions), and man-made exposures (e.g., noise, air pollutants, and toxins/chemicals). This is important for health care providers to recognize as one (or several) of these environmental factors could be playing a clinically meaningful role in elevating BP or disrupting hypertension control among their patients. At the population level, certain environmental exposures may even be contributing to the growing pandemic of hypertension. Here we provide an updated review of the literature linking environment exposures with high BP and outline practical recommendations for clinicians.

Associations of short-term exposure to ambient air pollutants with emergency ambulance calls for the exacerbation of essential arterial hypertension

We investigated the association between daily emergency ambulance calls (EAC) for elevated blood pressure that occurred during the time intervals of 8:00-13:59, 14:00-21:59, and 22:00-7:59, and exposure to CO, PM₁₀, and ozone. We used Poisson regression to explore the association between the risk of EAC and short-term variation of pollutants, adjusting for seasonality and weather variables. Before noon, the risk was associated with an interquartile range (IQR) (7.9 μg/m³) increase in PM₁₀ at lag 2-4 days below the median (RR = 1.08, p = 0.031) and with an IQR (0.146 mg/m³) increase in CO at lag 6-7 below the median (RR = 1.05, p = 0.028). During 14:00-21:59, the risk was associated with an IQR (18.8 μg/m³) increase in PM₁₀ on the previous day below the median (RR = 1.04, p = 0.031). At night, EAC were negatively affected by lower O₃ (lag 0-2) below the median (per IQR decrease RR = 1.10, p = 0.018) and a higher PM₁₀ at lag 0-1 above the median for the elderly (RR = 1.07, p = 0.030).

Association between sleep difficulties as well as duration and hypertension: is BMI a mediator?

Sleep difficulties and short sleep duration have been associated with hypertension. Though body mass index (BMI) may be a mediator variable, the mediation effect has not been defined. We aimed to assess the association between sleep duration and sleep difficulties with hypertension, to determine if BMI is a mediator variable, and to quantify the mediation effect. We conducted a mediation analysis and calculated prevalence ratios with 95% confidence intervals. The exposure variables were sleep duration and sleep difficulties, and the outcome was hypertension. Sleep difficulties were statistically significantly associated with a 43% higher prevalence of hypertension in multivariable analyses; results were not statistically significant for sleep duration. In these analyses, and in sex-specific subgroup analyses, we found no strong evidence that BMI mediated the association between sleep indices and risk of hypertension. Our findings suggest that BMI does not appear to mediate the association between sleep patterns and hypertension. These results highlight the need to further study the mechanisms underlying the relationship between sleep patterns and cardiovascular risk factors.

Quantifying Infra-slow Dynamics of Spectral Power and Heart Rate in Sleeping Mice

Three vigilance states dominate mammalian life: wakefulness, non-rapid eye movement (non-REM) sleep, and REM sleep. As more neural correlates of behavior are identified in freely moving animals, this three-fold subdivision becomes too simplistic. During wakefulness, ensembles of global and local cortical activities, together with peripheral parameters such as pupillary diameter and sympathovagal balance, define various degrees of arousal. It remains unclear the extent to which sleep also forms a continuum of brain states-within which the degree of resilience to sensory stimuli and arousability, and perhaps other sleep functions, vary gradually-and how peripheral physiological states co-vary. Research advancing the methods to monitor multiple parameters during sleep, as well as attributing to constellations of these functional attributes, is central to refining our understanding of sleep as a multifunctional process during which many beneficial effects must be executed. Identifying novel parameters characterizing sleep states will open opportunities for novel diagnostic avenues in sleep disorders. We present a procedure to describe dynamic variations of mouse non-REM sleep states via the combined monitoring and analysis of electroencephalogram (EEG)/electrocorticogram (ECoG), electromyogram (EMG), and electrocardiogram (ECG) signals using standard polysomnographic recording techniques. Using this approach, we found that mouse non-REM sleep is organized into cycles of coordinated neural and cardiac oscillations that generate successive 25-s intervals of high and low fragility to external stimuli. Therefore, central and autonomic nervous systems are coordinated to form behaviorally distinct sleep states during consolidated non-REM sleep. We present surgical manipulations for polysomnographic (i.e., EEG/EMG combined with ECG) monitoring to track these cycles in the freely sleeping mouse, the analysis to quantify their dynamics, and the acoustic stimulation protocols to assess their role in the likelihood of waking up. Our approach has already been extended to human sleep and promises to unravel common organizing principles of non-REM sleep states in mammals.

Differences in short and long sleep durations between blacks and whites attributed to emotional distress: analysis of the National Health Interview Survey in the United States

OBJECTIVES

The current study examined the role of emotional distress in explaining racial/ethnic differences in unhealthy sleep duration.

DESIGN

Data from the 2004-2013 National Health Interview Survey were analyzed using SPSS 20.

SETTING

Data were collected through personal household interviews in the United States.

PARTICIPANTS

Of the total 261,686 participants (age≥18 years), 17.0% were black, 83.0% were white, and the mean age was 48 years (SE=0.04).

MEASUREMENTS

To ascertain total sleep duration, participants were asked, "How many hours of sleep do you get on average in a 24-hour period?" Sleep duration was coded as short sleep (<7hours), average sleep (7-8hours), or long sleep (>8hours). Emotional distress-feeling sad, nervous, restless, hopeless, worthless, and burdened over a 30-day period-was measured using Kessler-6, a 6-item screening scale.

RESULTS

Of the participants reporting significant emotional distress (4.0% black, 3.5% white), χ² analyses revealed that a higher percentage of blacks, compared with whites, reported unhealthy sleep durations. Relative to Whites, Blacks had increased prevalence of short sleep (prevalence ratio=1.32, P<.001) or long sleep (odds ratio =1.189, P<.001). The interaction between race/ethnicity and emotional distress was significantly associated with short (prevalence ratio=0.99, P<.001) and long sleep (odds ratio=0.98, P<.001) durations.

CONCLUSIONS

Individuals of the black race/ethnicity or those reporting greater levels of emotional distress are more likely to report short or long sleep duration. Emotional distress might partially explain racial/ethnic differences in unhealthy sleep duration between blacks and whites.