Job Stress and Heart Rate Variability: Findings From the ELSA-Brasil Cohort

OBJECTIVE

Evidence suggests that exposure to psychosocial stress at work can inhibit vagal tonus, influencing the capacity to respond to environmental stimuli. We investigated whether job strain and low control and high demand at work, as separate measures, are associated with a reduction in heart rate variability (HRV).

METHODS

This is a cross-sectional study with 9658 active workers at the baseline (2008-2010) of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). HRV was estimated using electrocardiographic recordings for 10 minutes, at rest, examining the following indices were used: root mean square of successive difference, standard deviation of normal to normal, percentage of adjacent R-R intervals with a difference lasting more than 50 ms, low frequency (LF), and high frequency. Job strain was defined based on the demand-control model. Independent associations between job strain and HRV indices were verified using generalized linear models and the magnitude of the association was estimated by evaluating the ratios of arithmetic means.

RESULTS

Neither the unfavorable demand-control relation nor job demand dimension separately was associated with HRV. However, the increase of one unit in the control dimension was associated with an increment of 2.2% (95% confidence interval = 1.014-1.029) in the LF mean. After adjustments for sociodemographic characteristics, assessment site, health-related behaviors, and depression, this association remained statistically significant (ratio of arithmetic means = 1.008; 95% confidence interval = 1.0002-1.017).

CONCLUSIONS

Job control was associated with HRV in a large cohort of civil servants. Nevertheless, it is important to emphasize that only the LF index remained associated with low job control. Further studies are needed to develop a greater understanding of the relationship of psychosocial aspects and autonomic balance.

Oro-facial pain experience among symphony orchestra musicians in Finland is associated with reported stress, sleep bruxism and disrupted sleep-Independent of the instrument group

BACKGROUND

To evaluate whether oro-facial pain experience was related to the type of musical instrument and to learn more about the roles of sleep and sleep-related issues in the pain among professional musicians.

OBJECTIVES

A standard questionnaire was sent to all Finnish symphony orchestras (n = 19), with altogether 1005 professional musicians and other personnel.

METHODS

The questionnaire covered descriptive data, instrument group, items on perceived quality of sleep, possible sleep bruxism, stress experience and oro-facial pain experience during the past 30 days.

RESULTS

In the present study, which included the musicians only, the response rate was 58.7% (n = 488). All orchestras participated in the study, and there was no significant difference in the response rate between the orchestras. The mean age of men (52.3%) was 47.7 (SD 10.3) and of women (47.7%) was 43.4 (SD 9.8) years (P < 0.001). Overall, current pain in the oro-facial area was reported by 28.9%, frequent bruxism by 12.1% and frequent stress by 20.8%. According to Somers' d, there were statistically significant but moderate correlations between overall pain reports in the oro-facial area and disrupted sleep (d = 0.127, P = 0.001), sleep bruxism (d = 0.241, P < 0.001) and stress experiences (d = 0.193, P < 0.001). Logistic regression revealed, independent of the instrument group (string, woodwind, brass wind, percussion), that current oro-facial pain experience was significantly associated with disrupted sleep (P = 0.001), frequent sleep bruxism (P < 0.001) and frequent stress (P = 0.002) experiences.

CONCLUSIONS

Among symphony orchestra musicians, oro-facial pain experience seems to be related to perceptions of stress, sleep bruxism and disrupted sleep rather than the instrument group.

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.

Attenuation of vagal recovery during sleep and reduction of cortisol/melatonin ratio in late afternoon associate with prolonged daytime sleepiness among media workers with irregular shift work

BACKGROUND

Media work is characterized by information flow, deadlines, and 24/7 alertness. Good recovery prevents stress-related disorders.

METHODS

The standardized questionnaire included items about health, health habits, sleep, work conditions, and work stress. Recordings of 24-hr heart rate variability (HRV) and four salivary samples for cortisol and melatonin levels were analyzed from 70 randomly selected workers with irregular shift work, and 70 workers with normal daytime work.

RESULTS

Irregular shift work increased the risk of insufficient recovery when compared to normal daytime work (OR 2.0; P < 0.05). In the group of workers with insufficient subjective recovery, HRV was attenuated (P < 0.05) during the early hours of night, and cortisol/melatonin ratio was decreased (P < 0.05) in the afternoon.

CONCLUSIONS

Physiological changes underlying subjective feelings of insufficient recovery are measurable. Attenuated HRV during sleep reflects prolonged sympathetic drive and/or impaired parasympathetic recovery. Interactions between cortisol and melatonin hormones might be involved in the development of chronic exhaustion.

Morning cortisol levels and perceived stress in irregular shift workers compared with regular daytime workers

The 24/7 work environment and irregular shifts may markedly enhance the psychological pressure of media work. Changes in the hypothalamic-pituitary-adrenal axis reflect adaptation to stress. We analysed the correlation between subjective stress, sleep, salivary cortisol, and melatonin hormones among Finnish media workers with regular daytime work (RDW) and with irregular shift work (ISW) while controlling confounders. From 874 employees with regular daytime work or with irregular shift work, 70 employees from both groups were randomly selected. The final number of employees with a complete salivary cortisol profile was 66 in the RDW group and 65 in the ISW group. Five saliva samples were gathered from each subject before and during a working day. The salivary cortisol level of the sample taken 60 minutes after awakening (T1) was compared to the salivary cortisol level taken immediately after awakening (T0, T1/T0 ratio). The ratio was higher in the ISW group than in RDW group. Irregular shift work (P < 0.001), severe stress (P < 0.05), and less sleep (P < 0.05) were independently associated with an augmented cortisol response after awakening. A stressful work environment and irregular shift work enhance cortisol excretion after waking. In the long run, this may become detrimental to health.

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.