Reduced vagal cardiac control variancein exhausted and high strain job subjects

Work stress and changes in heart rate variability among employees after first acute coronary syndrome: a hospital-based longitudinal cohort study

Background

Work stress is considered as a risk factor for coronary heart disease, but its link with heart rate variability (HRV) among heart attack survivors is unknown yet. The aim of this study was to investigate associations between baseline work stress and the changes of HRV over one-year after onset of acute coronary syndrome (ACS).

Methods

Hundred and twenty-two patients with regular paid work before their first ACS episode were recruited into this hospital-based longitudinal cohort study. During hospitalization (baseline), all patients underwent assessments of work stress by job strain (JS) and effort-reward imbalance (ERI) models, and were assigned into low or high groups; simultaneously, sociodemographic and clinical data, as well depression, anxiety, and job burnout, were collected. Patients were followed up 1, 6, and 12 months after discharge, with HRV measurements at baseline and each follow-up point. Generalized estimating equations were used to analyze the effects of baseline work stress on HRV over the following 1 year.

Results

After adjusting for baseline characteristics and clinical data, anxiety, depression, and burnout scores, high JS was not associated with any HRV measures during follow-up (all p > 0.10), whereas high ERI was significantly related to slower recovery of 5 frequency domain HRV measures (TP, HF, LF, VLF, and ULF) (all p < 0.001), and marginally associated with one time domain measure (SDNN) (p = 0.069). When mutually adjusting for both work stress models, results of ERI remained nearly unchanged.

Conclusion

Work stress in terms of ERI predicted lower HRV during the one-year period after ACS, especially frequency domain measures.

Determining the direction of prediction of the association between parasympathetic dysregulation and exhaustion symptoms

Stress-related exhaustion symptoms have a high prevalence which is only likely to increase further in the near future. Understanding the physiological underpinnings of exhaustion has important implications for accurate diagnosis and the development of effective prevention and intervention programs. Given its integrative role in stress-regulation, the parasympathetic branch of the autonomic nervous systems has been a valid starting point in the exploration of the physiological mechanisms behind exhaustion. The aim of the present study was to examine the directionality and specificity of the association between exhaustion symptoms and vagally-mediated heart rate variability (vmHRV), a relatively pure measure of parasympathetic tone. Exhaustion symptoms and vmHRV were measured at four annually assessment waves (2015-2018) of the Dresden Burnout Study. A total sample of N = 378 participants who attended at least two of the four annual biomarker measurements were included in the present analyses. Cross-lagged multi-level panel modelling adjusting for various covariates (e.g., age, sex, BMI) revealed that vmHRV was meaningfully predictive of exhaustion symptoms and not vice versa. In addition, these effects were specific for exhaustion symptoms as no effect was shown for the other burnout sub-dimensions, or for depressive symptoms. Our findings indicate a clear link between exhaustion symptoms and vmHRV which may hold great potential for both enhancing the diagnosis and treatment of exhaustion symptoms.

Influence of daytime blue-enriched bright light on heart rate variability in healthy subjects

Heart rate variability (HRV), the indicator of the autonomic nervous system-induced modulation of heart rate, is a focal topic in psychophysiological research. The effect of indoor light on HRV may be related to various psychophysiological functions. The current study (N = 20) examined the response of the autonomic nervous system (ANS) to bright vs. dim blue-enriched light (1200 lx or 200 lx at eye level, 6500 K) exposure for five hours in the afternoon among healthy young adults. The results revealed a significant main effect of light condition on the time-domain indicators, with the significantly higher HRV (SDNN and RMSSD) under 200 lx versus 1200 lx condition, and the same case was revealed for the standard deviations of the Poincaré plot in non-linear effects. Conversely, no significant effects were revealed for the frequency- domain indicators of HRV measured with the subjects' eyes open. These findings suggested that the autonomic nervous system modulation of HRV was stronger under bright light conditions.

Identification of a High-Risk Group of New-Onset Cardiovascular Disease in Occupational Drivers by Analyzing Heart Rate Variability

Purpose: This cohort study evaluated the effectiveness of noninvasive heart rate variability (HRV) analysis to assess the risk of cardiovascular disease over a period of 8 years. Methods: Personal and working characteristics were collected before biochemistry examinations and 5 min HRV tests from the Taiwan Bus Driver Cohort Study (TBDCS) in 2005. This study eventually identified 161 drivers with cardiovascular disease (CVD) and 627 without between 2005 and 2012. Estimation of the hazard ratio was analyzed by using the Cox proportional-hazards model. Results: Subjects with CVD had an overall lower standard deviation of NN intervals (SDNN) than their counterparts did. The SDNN index had a strong association with CVD, even after adjusting for risk factors. Using a median split for SDNN, the hazard ratio of CVD was 1.83 (95% CI = 1.10–3.04) in Model 1 and 1.87 (95% CI = 1.11–3.13) in Model 2. Furthermore, the low-frequency (LF) index was associated with a risk of CVD in the continuous approach. For hypertensive disease, the SDNN index was associated with increased risks in both the continuous and dichotomized approaches. When the root-mean-square of the successive differences (RMSSDs), high frequency (HF), and LF were continuous variables, significant associations with hypertensive disease were observed. Conclusions: This cohort study suggests that SDNN and LF levels are useful for predicting 8 year CVD risk, especially for hypertensive disease. Further research is required to determine preventive measures for modifying HRV dysfunction, as well as to investigate whether these interventions could decrease CVD risk among professional drivers.

Low self-reported stress despite immune-physiological changes in paramedics during rescue operations

Despite the high stress levels, paramedics seem to ignore or even negate the stress. This can be detrimental and lead to stress-related diseases. Therefore, we investigated the divergence between physiological and psychological stress responses of paramedics. Participants were 16 paramedics and 17 white-collar workers. We assessed psychological stress parameters, cortisol awakening response (CAR), and quantified immune parameters. In paramedics, electrocardiogram (ECG) was measured during one complete 24-hour shift. Our results revealed that CAR was higher in paramedics compared to controls. An alteration of immune parameters was observed even during days of free time. Also, ECG recordings showed acute stress in paramedics during rescue situations. Questionnaires revealed that rescue-service specific stressors affect psychological outcomes. However, paramedics reported significantly less mental stress and higher levels of depersonalization than controls. Taken together, our results suggest higher stress in paramedics compared to controls. However, paramedics negate their daily stress. Our findings underline therefore the importance to develop stress-management interventions for paramedics including sensitization for their stress reactions.

The interactive effects of heart rate variability and mindfulness on indicators of well-being in healthcare professionals' daily working life

OBJECTIVE

Heart rate variability (HRV) and mindfulness have been described as correlates of self-regulation and well-being. The goal of the present study was to investigate their interactions from a within-person perspective in the context of work.

METHODS

Applying an ambulatory assessment approach, we studied 89 healthcare professionals across two to four work shifts. Self-reports of momentary job demands, mindfulness, and well-being (as indicated by emotional exhaustion, relaxation, and contentment) were provided three to four times a day via smartphone questionnaires. Electrocardiogram and activity sensors continuously recorded data from the beginning to the end of the shifts. Multilevel models based on 937 measurements were built for emotional exhaustion, relaxation, and contentment.

RESULTS

After controlling for covariates, including bodily movement, shift, and job demands, short-term HRV was marginally significantly related to decreased emotional exhaustion and significantly related to increased relaxation. State mindfulness was significantly related to decreased emotional exhaustion, and increased relaxation and contentment. Furthermore, HRV and mindfulness significantly interacted such that emotional exhaustion was lowest and relaxation was highest when both HRV and mindfulness were high.

CONCLUSIONS

Together, the findings provide insights into the use of HRV and mindfulness as indexes of psychophysiological regulatory resources that seemingly intensify their respective beneficial effects on the daily well-being of employees.

Job Demand-Control-Support Latent Profiles and Their Relationships with Interpersonal Stressors, Job Burnout, and Intrinsic Work Motivation

In the Job Demand-Control-Support (JDCS) model, the combination of job demands, job control, and social support was hypothesized to lead to eight different constellations of job types. According to the model, these constellations are linked to wellbeing/health and learning outcomes. In the last three decades, these constellations of job types have been investigated by adopting a variable-centered perspective. However, latent profile analyses (LPA) enable a person-centered approach and empirically capture constellations of job types. In the present study, we used LPA to empirically identify distinct profiles of JDCS among Italian healthcare workers. Furthermore, we investigated the role of social stressors (workplace relationships and coworkers’ incivility) as antecedents of these profiles and the association of these profiles with job burnout and work motivation. Results from LPA (n = 1671) revealed four profiles: Isolated Prisoner, Participatory Leader, Moderate Strain, and Low Strain. Negative relationships at work and coworkers’ incivility increased the chances of being included in both Isolated prisoner and Participatory Leader profiles. Finally, the Isolated Prisoner and Moderate Strain profiles showed the highest levels of emotional exhaustion and cynicism and the lower levels of intrinsic work motivation. This study extends previous JDCS research, highlighting that researchers should consider empirically identified profiles rather than theoretically defined subgroups. Implications for stress theory, future research, and practice are discussed.

Inertia of emotions and inertia of the heart: Physiological processes underlying inertia of negative emotions at work

Emotional inertia is a key feature of emotional dynamics and it refers to the degree to which a current emotional state can be predicted by a previous emotional state. In this study, using the experience sampling method, we examined the relationship between inertia of negative emotions at work and parasympathetic activity, measured by vagally-mediated heart rate variability (HRV). In line with current literature on HRV, we propose that temporal dependency of negative emotions at work may be associated to lower HRV, an important marker of the ability to flexibly adjust to a changing environment. Participants (n = 120) were prompted six times during a regular workday, while wearing a heart rate monitor. In accordance with the polyvagal theory and the model of neurovisceral integration, findings supported our hypothesis and indicated that workers with lower HRV tend to show high time persistence of negative emotions at work. Practical implications and directions for future research are discussed.

Teachers' ambulatory heart rate variability as an outcome and moderating variable in the job demands-resources model

Background and Objectives: According to the job demands-resources (JD-R) model, strain reactions are based on the level of job demands and moderating resources. The present study aims to contribute to psychophysiological research by integrating vagally mediated heart rate variability (HRV) into the JD-R framework. Design and Methods: Using a sample of school teachers, we conducted an ambulatory assessment study to investigate HRV as (1) a state outcome measure of job demands and resources and (2) a trait moderator in the relationship between job demands and emotional exhaustion. In total, 101 participants wore an electrocardiogram device on two school days and rated their level of job demands (emotional demands and time pressure), job resources (control and support), and exhaustion six times a day. Based on 669 measurements, multilevel models of the 5-minute state HRV measure and emotional exhaustion were built. Results: The results supported the health-impairing effects of job demands on emotional exhaustion but not state HRV. There was no evidence of the moderating effects of job resources. Notably, the 48-hour trait HRV measure significantly buffered the effect of emotional demands on exhaustion. Conclusions: These findings highlight the stress-buffering potential of trait HRV as theoretical research extension and practical intervention goal.

Association between Work-Related Stress and QT Prolongation in Male Workers

Background: Work-related stress is a potential cardiovascular risk factor, but the underlying mechanism is not fully explained. The autonomic nervous system control of cardiac function might play a specific role; therefore, monitoring the QT interval in the electrocardiogram can highlight an autonomic imbalance induced by occupational stressors. The aim of our study was to explore the QT interval parameters as early indicators of imbalance of the autonomic cardiac function in relation to work-related stress. Methods: During 2015–2016 annual workplace health surveillance, we measured work-related stress in 484 workers of a logistic support company using the Health and Safety Executive (HSE) tool. We assessed the frequency-corrected QT (QTc) interval and the QT index (QTi) on the electrocardiogram of each participant, and collected demographic and clinical data. We compared the QTc values by the four Karasek’s categories (active/passive jobs, low/high strain job), and by job support (present/lacking), and conducted multivariate analysis to adjust for possible confounders. Results: The results of the multivariate regression analysis showed that QTc was prolonged among workers operating at a specific site where stress level was found to be elevated. Regular physical activity showed a beneficial effect against QTc prolongation. We did not observe an effect on QTc length by the cross-combined Karasek’s categories of job control, job demand, and job support. Conclusions: Our study suggests subclinical effects of conditions associated with work-related stress on the autonomic regulation of cardiac function. Further research is warranted to elucidate the combined effect of work organization and lifestyle factors on autonomic cardiac function.

Psychophysiological concomitants of burnout: Evidence for different subtypes

BACKGROUND

There is evidence that chronic stress and emotional exhaustion are related to physiological dysregulations, which could negatively impact physical and mental health. This study aimed to identify the specific physiological clusters which are most reliable and prominently associated with burnout. Emphasis was placed on variables of the autonomic nervous system and hypothalamic-pituitary-adrenal axis. Burnout was assessed using the Emotional Exhaustion subscale of the German version of the Maslach Burnout Inventory (MBI-GS).

METHODS

A sample of 105 individuals aged between 28 and 60 years (M = 42.7, SD = 7.75) and working under highly demanding conditions participated in this study. 46 participants reported a low risk of burnout, and 58 participants a high risk. They underwent 24 h of ECG monitoring, had cortisol awakening response collected, and had blood pressure measured two times within a week.

RESULTS

Compromised HRV, higher cortisol values, and higher blood pressure were found in individuals with high burnout symptoms. Furthermore, a discriminant function analysis on cardiac and neuroendocrine variables suggested two subgroups within the high burnout individuals, with only one group showing evidence for autonomic dysfunction as indicated by lower vagal efference.

CONCLUSIONS

Results suggest that burnout might not necessarily imply physiological disturbances, thus calling for a more differentiated and individualized view of burnout.

The Longitudinal Association of Reduced Vagal Tone With Burnout

OBJECTIVE

Previous research indicates a link between burnout symptoms and reduced vagally mediated heart rate variability (HRV); however, the directionality of this relationship is still largely unknown. The objective of the present study was to examine the longitudinal relationship between HRV and burnout symptoms for 1 year, with a special focus on the emotional exhaustion (EE) burnout subdimension, which remains inadequately distinguished from overlapping with depressive symptoms.

METHODS

Here we present HRV and behavioral data from 167 individuals (mean [SD] age = 43.43 [11.78] years; 30.5% male) who attended two biomarker samplings (T1 and T2) of the Dresden Burnout Study approximately 12 months apart.

RESULTS

In hierarchical linear regression analyses, T1 HRV significantly inversely predicted T2 overall burnout symptoms (β = -.16; p = .03) and EE (β = -.23; p = .02), adjusting for age, sex, body mass index, adverse health behaviors, and depressive symptoms. Importantly, only high EE at T1 (β = -.22; p = .04), and not the T1 Maslach Burnout Inventor total score, predicted reductions in HRV from T1 to T2.

CONCLUSIONS

We report for the first time longitudinal evidence that HRV is associated with changes in burnout symptoms, independently of depressive symptoms. Results suggest vagal dysfunction being predictive and specific for burnout symptoms, making HRV a promising starting point for the explanation of biophysiological mechanisms underlying burnout symptoms and cardiovascular diseases. The finding of only EE at T1 being predictive for changes in HRV underscores the importance of exhaustion for modulations in autonomic regulation.

Heart rate variability and occupational stress-systematic review

The aim of this systematic review was to explore studies regarding association between occupational stress and heart rate variability (HRV) during work. We searched PubMed, Web of Science, Scopus, Cinahl and PsycINFO for peer-reviewed articles published in English between January 2005 and September 2017. A total of 10 articles met the inclusion criteria. The included articles were analyzed in terms of study design, study population, assessment of occupational stress and HRV, and the study limitations. Among the studies there were cross-sectional (n=9) studies and one longitudinal study design. Sample size varied from 19 to 653 participants and both females and males were included. The most common assessment methods of occupational stress were the Job Content Questionnaire (JCQ) and the Effort-Reward Imbalance (ERI) questionnaire. HRV was assessed using 24 h or longer Holter ECG or HR monitoring and analyzed mostly using standard time-domain and frequency-domain parameters. The main finding was that heightened occupational stress was found associated with lowered HRV, specifically with reduced parasympathetic activation. Reduced parasympathetic activation was seen as decreases in RMSSD and HF power, and increase in LF/HF ratio. The assessment and analysis methods of occupational stress and HRV were diverse.

Work Related Stress, Well-Being and Cardiovascular Risk among Flight Logistic Workers: An Observational Study

Work-related stress is a known occupational hazard, with a putative role on the development of cardiovascular diseases (CVD). Although several investigations have explored the association in various workplace scenarios, none have focused on the airport flight logistic support personnel, a transportation business of crucial importance, potentially exposed to job stress and consequently to an increase in CVD risk. We explored the relationship between work-related stress and cardiovascular risk in 568 healthy workers of a flight logistic support company using the Health and Safety Executive questionnaire, the Framingham Heart Study General Cardiovascular Disease (CVD) Risk Prediction Score, and the WHO general well-being index (WHO-5). We used univariate and multivariate statistical methods to take account of possible confounders. Our results show that a low job support significantly increases the CVD risk score and decreases the WHO well-being index with reference to subjects reporting high support on the job. In addition, the well-being index of workers with high strain jobs appears lower in respect to workers employed in low strain job. The multivariate analysis confirms a protective effect of job support, and shows a detrimental influence on CVD risk by physical inactivity, regular intake of alcohol, and a low educational level. In addition, job control, job support, low strain, and high demand coupled with high control (active job) showed a beneficial effect on psychological well-being. Our results suggest that a combination of general risk factors and organizational factors contributes to increase CVD risk and well-being, representing a crucial target for intervention strategies to promote health in the workplace.

The impact of occupational psychological hazards and metabolic syndrome on the 8-year risk of cardiovascular diseases-A longitudinal study

There was little information concerning the combined effect of occupational psychosocial hazards such as long working hours, high job stress, and high fatigue on the risk of cardiovascular and cerebrovascular diseases (CVD). The aim of this study was to investigate the interaction among occupational psychosocial hazards and the impact of metabolic syndrome (MetS) on the risk of CVD among bus drivers. The Taiwan Bus Driver Cohort Study involving 1014 professional drivers was established in 2005 and comprehensively studied. The interactions among occupational psychosocial hazards and the impact of MetS on the risk of CVD were measured. A working pattern questionnaire, job stress questionnaires, the Swedish occupational fatigue inventory, the stress satisfaction offset score, biochemical measurements, and physical examinations were used to assess psychosocial hazards and the presence of metabolic syndrome. There were 707 eligible bus drivers with a mean age of 43.5years old. During the 8-years of follow-up, 77 drivers were diagnosed with CVD. Long working hours, high job stress, and high fatigue were associated with an increased risk of cardiovascular disease incidence in the multivariate analysis. There were synergistic effects among long working hours, high job stress, and high fatigue only in drivers with MetS. A combination of long working hours, high job stress, and high fatigue increased the risk of developing CVD in bus drivers with MetS.

Heart Rate Variability Frequency Domain Alterations among Healthy Nurses Exposed to Prolonged Work Stress

The deregulation of the autonomic nervous system assessed through the heart rate variability (HRV) analysis is a promising pathway linking work stress and cardiovascular diseases. We aim to investigate the associations between HRV High Frequency (HF) and Low Frequency (LF) powers and work stress in a sample of 36 healthy nurses. Perceived work stress was assessed twice one year apart, using the Job Content and Effort Reward Imbalance questionnaires. This allows to classify nurses in three exposure groups: “prolonged high stress” (PHS), “recent high stress” (RHS) and “stable low stress” (SLS). A 24-h ECG monitoring was later performed during a working day (WD) and a subsequent resting day (RD). Statistically significantly lower (p < 0.02) HF and LF means were found in PHS and RHS nurses during the working periods. In the subsequent resting periods, HF means showed increases over time in the RHS (beta = +0.41, p < 0.05), but not in PHS nurses. LF means did not show any substantial increases in the resting periods, in the PHS group with geometric means lower when compared to SLS, in the non-working and resting periods. Our study evidences that both prolonged and recent perceived high work stress were associated with a reduction of HF and LF powers during work. In addition, prolonged stress was associated with a lack of recovery during not-working and resting periods.

Autonomic dysregulation in burnout and depression: evidence for the central role of exhaustion

Objectives Given the important role of the autonomic nervous system (ANS) in stress regulation, astonishingly little is known about ANS functioning in burnout, a condition arising after prolonged exposure to work-related stress. The current study sought to investigate ANS modulation, as indexed by vagally-mediated heart rate variability (HRV), in relation to burnout symptomatology to (i) distinguish associations between the three dimensions of burnout [emotional exhaustion (EE), cynicism, reduced personal accomplishment] and (ii) investigate overlap in associations with depressive symptomatology. Methods Assessments of vagally-mediated HRV (ie, root mean square of successive differences, RMSSD) were conducted in a large population-based sample from the Dresden Burnout Study [N=410, mean age 42.2, standard deviation (SD) 11.2 years; 33.4% male]. Vagally-mediated HRV was assessed for 90 seconds during an emotionally-arousing situation (venipuncture, recumbent), a 335-second recumbent recovery period, and a 335-second seated resting condition. Results Results from multiple linear regression analyses revealed that EE was negatively related to RMSSD during venipuncture (=β -0.11, P=0.03) and the seated rest (β= -0.09, P=0.04) even after accounting for established ANS modulators (eg, age, body mass index). This pattern was not observed for the other dimensions of burnout. Exploratory analyses of depressive symptomatology further revealed that RMSSD was significantly and inversely associated with burnout-related symptoms but not with the core criteria of depression (eg, depressed mood). Conclusions This study presents evidence for a link between exhaustion and reduced vagal function, both in burnout and depression, suggesting that ANS modulations may not be disorder-specific but rather a psychophysiological correlate of an underlying feature shared by both conditions.

Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research - Recommendations for Experiment Planning, Data Analysis, and Data Reporting

Psychophysiological research integrating heart rate variability (HRV) has increased during the last two decades, particularly given the fact that HRV is able to index cardiac vagal tone. Cardiac vagal tone, which represents the contribution of the parasympathetic nervous system to cardiac regulation, is acknowledged to be linked with many phenomena relevant for psychophysiological research, including self-regulation at the cognitive, emotional, social, and health levels. The ease of HRV collection and measurement coupled with the fact it is relatively affordable, non-invasive and pain free makes it widely accessible to many researchers. This ease of access should not obscure the difficulty of interpretation of HRV findings that can be easily misconstrued, however, this can be controlled to some extent through correct methodological processes. Standards of measurement were developed two decades ago by a Task Force within HRV research, and recent reviews updated several aspects of the Task Force paper. However, many methodological aspects related to HRV in psychophysiological research have to be considered if one aims to be able to draw sound conclusions, which makes it difficult to interpret findings and to compare results across laboratories. Those methodological issues have mainly been discussed in separate outlets, making difficult to get a grasp on them, and thus this paper aims to address this issue. It will help to provide psychophysiological researchers with recommendations and practical advice concerning experimental designs, data analysis, and data reporting. This will ensure that researchers starting a project with HRV and cardiac vagal tone are well informed regarding methodological considerations in order for their findings to contribute to knowledge advancement in their field.

Executive Cognitive Functioning and Cardiovascular Autonomic Regulation in a Population-Based Sample of Working Adults

Objective: Executive cognitive functioning is essential in private and working life and is sensitive to stress and aging. Cardiovascular (CV) health factors are related to cognitive decline and dementia, but there is relatively few studies of the role of CV autonomic regulation, a key component in stress responses and risk factor for cardiovascular disease (CVD), and executive processes. An emerging pattern of results from previous studies suggest that different executive processes may be differentially associated with CV autonomic regulation. The aim was thus to study the associations between multiple measures of CV autonomic regulation and measures of different executive cognitive processes. Method: Participants were 119 healthy working adults (79% women), from the Swedish Longitudinal Occupational Survey of Health. Electrocardiogram was sampled for analysis of heart rate variability (HRV) measures, including the Standard Deviation of NN, here heart beats (SDNN), root of the mean squares of successive differences (RMSSD), high frequency (HF) power band from spectral analyses, and QT variability index (QTVI), a measure of myocardial repolarization patterns. Executive cognitive functioning was measured by seven neuropsychological tests. The relationships between CV autonomic regulation measures and executive cognitive measures were tested with bivariate and partial correlational analyses, controlling for demographic variables, and mental health symptoms. Results: Higher SDNN and RMSSD and lower QTVI were significantly associated with better performance on cognitive tests tapping inhibition, updating, shifting, and psychomotor speed. After adjustments for demographic factors however (age being the greatest confounder), only QTVI was clearly associated with these executive tests. No such associations were seen for working memory capacity. Conclusion: Poorer CV autonomic regulation in terms of lower SDNN and RMSSD and higher QTVI was associated with poorer executive cognitive functioning in terms of inhibition, shifting, updating, and speed in healthy working adults. Age could largely explain the associations between the executive measures and SDNN and RMSSD, while associations with QTVI remained. QTVI may be a useful measure of autonomic regulation and promising as an early indicator of risk among otherwise healthy adults, compared to traditional HRV measures, as associations between QTVI and executive functioning was not affected by age.

QTc interval and electrocardiographic changes by type of shift work

BACKGROUND

We conducted a cross sectional survey of electrocardiographic changes among shift-workers.

METHODS

We classified the electrocardiogram morphology, and measured the QTc interval in 91 male workers engaged in regular daily work-shifts, 32 in 24 hr work-shift (h24), and 93 in irregular 6 hr work-shift (h6).

RESULTS

With reference to daily workers, the QTc interval was prolonged among h6 workers (P < 0.001) and h24 workers (P < 0.005). The age- and obesity-adjusted standardized prevalence ratio (SPR) of a borderline/prolonged QTc was 2.2-fold among h6 workers (95% CI 1.2, 4.2); conduction disorders (SPR = 2.6; 95% CI 1.3, 5.2) and repolarization disorders (SPR = 1.9; 95% CI 1.0, 3.5) were also more frequently observed among h6 workers. Excluding 19 subjects with risk factors for prolonged QTc did not change the results.

CONCLUSIONS

Our study reveals significant changes in the ECG morphology in relation to shift-work, especially in unpredictable and non-standard working hours.

Autonomic nervous system activity and workplace stressors--a systematic review

AIM

This systematic review evaluates and summarizes the evidence of the association between psychosocial work environment as indicated by several work-stress models such as Job-Demand-Control (JDC), Effort-Reward-Imbalance (ERI), or Organizational Justice (OJ) and autonomic nervous system (ANS) function as indexed by heart rate variability (HRV).

METHOD

We conducted a systematic literature search following the PRISMA-Statement in eleven databases including Medline, Web of Science and PsycINFO to address medical as well as psychological aspects of the relation between psychosocial work-stress models and HRV.

RESULTS

We identified 19 publications with a total of 8382 employees from ten countries reporting data from the years 1976-2008. Overall, nine of all studies report a negative and significant association between vagally-mediated HRV and measures of stress at work, while eight of all studies report a negative and significant association to mixed sympathetic and parasympathetic measures of HRV.

CONCLUSIONS

This systematic review provides evidence that adverse psychosocial work conditions are negatively associated with ANS function as indexed by HRV.

Job strain and shift work influences on biomarkers and subclinical heart disease indicators: a pilot study

This pilot study is one of the first to examine the impact of job strain and shift work on both the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis using two salivary stress biomarkers and two subclinical heart disease indicators. This study also tested the feasibility of a rigorous biological sampling protocol in a busy workplace setting. Paramedics (n = 21) self-collected five salivary samples over 1 rest and 2 workdays. Samples were analyzed for α-amylase and cortisol diurnal slopes and daily production. Heart rate variability (HRV) was logged over 2 workdays with the Polar RS800 Heart Rate monitors. Endothelial functioning was measured using fingertip peripheral arterial tonometry. Job strain was ascertained using a paramedic-specific survey. The effects of job strain and shift work were examined by comparing paramedic types (dispatchers vs. ambulance attendants) and shift types (daytime vs. rotating day/night). Over 90% of all expected samples were collected and fell within expected normal ranges. Workday samples were significantly different from rest day samples. Dispatchers reported higher job strain than ambulance paramedics and exhibited reduced daily alpha-amylase production, elevated daily cortisol production, and reduced endothelial function. In comparison with daytime-only workers, rotating shift workers reported higher job strain, exhibited flatter α-amylase and cortisol diurnal slopes, reduced daily α-amylase production, elevated daily cortisol production, and reduced HRV and endothelial functioning. Despite non-statistically significant differences between group comparisons, the consistency of the overall trend in subjective and objective measures suggests that exposure to work stressors may lead to dysregulation in neuroendocrine activity and, over the long-term, to early signs of heart disease. Results suggest that further study is warranted in this population. Power calculations based on effect sizes in the shift type comparison suggest a study size of n = 250 may result in significant differences at p = 0.05. High compliance among paramedics to complete the intensive protocol suggests this study will be feasible in a larger population.

Description of a large-scale study design to assess work-stress-disease associations for cardiovascular disease

We claim that a new level of studies is needed to answer a series of important questions about the expanding global chronic disease burden for cardiovascular disease (CVD) and for related conditions such as diabetes, metabolic syndrome, and obesity. These require a new study design structure, related to a new level of theory that goes beyond the current single-factor, a-theoretic epidemiological studies. This new platform for the design of large-scale Work/Stress/Disease studies would assess CVD-related disease mechanisms in a more general and dynamic form, based on the use of new tools for measuring autonomic functions in an occupational stress context and a new theory of disease causation. A sample outline is presented for such a study, based on Stress-Disequilibrium Theory (SDT) hypotheses, building on analytic tools developed for the assessment of stress-related exhaustion effects and chronic disease risks from Heart Rate Variability (HRV) research studies. The goal is to assess the associations between social organizational risks, particularly at work, and hypertension, metabolic syndrome, and diabetes II. The study design is multi-stage, spanning across several levels of disease-related de-regulation, and addressing co-morbidity of the conditions themselves. The study design is meant to span across a broad social population at all levels and would probably be multi-site, involving several countries, to yield the larger sample increased power for finding associations for work - physiological effects.