Heart rate variability in occupational health --a systematic review

Advanced and long-term meditation and the autonomic nervous system: A review and synthesis

Meditation has become prominent in both clinical and non-clinical applications for its effects on psychological and physical well-being. Long-term meditators, who have dedicated extensive time to their practice, present a unique opportunity to explore the effects of prolonged meditation training on the autonomic nervous system. Research has reported concomitant activation of both sympathetic (aroused) and parasympathetic (relaxed) branches of the autonomic nervous system during some forms of meditation, leading to the term 'relaxed alertness.' However, findings are not consistent, with reports of both sympathetic and parasympathetic activation, sympathetic-only, parasympathetic-only, or temporally variable activations, depending on several factors. This review synthesizes these heterogeneous and seemingly inconsistent results in relation to three explanatory factors: (1) specific classification of style or type of meditation; (2) specific definition of the level of expertise of the meditators; and (3) intra-individual variations within a given meditation practice. When these factors are considered, convergent and meaningful patterns emerge, allowing for a shift from the broad notion of 'long-term' meditation to a more precise characterization of 'advanced' meditation, highlighting skills, states, and stages of mastery developed over time. Our synthesis is particularly useful for understanding both long-term and advanced meditation, as it reveals specific heart rate variability patterns, including very low and low-frequency spectral power peaks, along with cardiac and respiratory coupling. Better characterization of the role of the autonomic nervous system in the context of advanced meditation promises to inform improved meditation training, including training assisted by technology, toward more impactful outcomes.

Heart Rate Variability and Interoception in Periodic Limb Movements in Sleep: Interference with Psychiatric Disorders?

Periodic limb movements in sleep (PLMS) are a prevalent disorder characterized by rhythmic, involuntary movements of the lower limbs, such as dorsiflexion of the ankle and extension of the big toe, occurring in periodic intervals during sleep. These movements are often linked to disrupted autonomic nervous system (ANS) activity and altered interoception. Interoception involves perceiving internal bodily states, like heartbeat, breathing, hunger, and temperature, and plays a crucial role in maintaining homeostasis and the mind-body connection. This review explores the complex relationships between PLMS, heart rate variability (HRV), ANS dysregulation, and their impact on psychiatric disorders. By synthesizing the existing literature, it provides insights into how ANS dysregulation and altered interoceptive processes, alongside PLMS, contribute to psychiatric conditions. The review highlights the potential for integrated diagnostic and therapeutic approaches and presents a cause-and-effect model illustrating the mutual influence of psychiatric disorders, ANS dysregulation, PLMS, and interoception.

Influence of Night Shift Work on Heart Rate Variability in an Age- and Gender-Matched Study Group

Regular and long-term shift work is associated with a number of chronic diseases. There is some evidence that shift work also has an influence on the autonomous nervous system. Studies that have examined the effect of shift work on heart rate variability (HRV) have not taken into account age and gender. Therefore, the aim of this study was to investigate the influence of night shift based on 24 h long-term analyses carried out on non-night shift days with a matched control group for age and gender. In total, 172 (128 male, 44 female) healthy shift night workers were compared with subjects from a non-night shift worker group at a ratio of 1:1, forming matched pairs based on the subjects' sex and age. HRV parameters were analyzed based on 24 h ECG recording. An analysis of the HRV parameters showed only a small difference but without statistical significance between the two groups with regard to all of the HRV parameters examined (SDNN, RMSSD, NN50, pNN50, VLF, LF, HF, LF/HF, DFA1, and DFA2). An analysis of the subgroup of subjects who had only worked night shifts for a minimum of 10 or 20 years, with the respective pairs matched by age and gender, did not reveal any significant differences between the HRV parameters of employees working night shifts and those not working night shifts. Taking into account qualitative aspects of HRV analysis, this study was thus able to show that working night shifts for many years may not have as big an influence on HRV as had been assumed so far.

Vagal predominance correlates with mood state changes of winter-over expeditioners during prolonged Antarctic residence

OBJECTIVE

Winter-over expeditioners in Antarctica are challenged by various environmental and psycho-social stress factors, which may induce psychophysiological changes. The autonomic nervous system (ANS) plays a crucial role in the adaptation process under stress. However, the relationship between ANS activity and the mood states of expeditioners remains largely unexplored. This study aims to uncover the pattern of ANS adjustment under extreme Antarctic environments and provide new insights into the correlations between ANS activity and mood state changes, which may provide scientific data for medical interventions.

METHODS

Fourteen expeditioners at Zhongshan Station participated in this study. The study was conducted during four representative periods: pre-Antarctica, Antarctica-1 (pre-winter), Antarctica-2 (winter), and Antarctica-3 (summer). The heart rate variability (HRV) of the expeditioners was continuously measured for 24 hours to evaluate ANS activity. Plasma levels of catecholamines were tested by ELISA. Mood states were assessed by the Profile of Mood States (POMS) scale.

RESULTS

HRV analysis showed a disturbance of ANS during winter and summer periods. For frequency domain parameters, very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) significantly increased during the second half of the mission. Especially, LF/HF ratio decreased during summer, indicating the predominance of vagal tone. Results of the time domain analysis showed increased heart rate variability during the austral winter and summer. Plasma epinephrine (E) significantly increased during residence in Antarctica. Compared with pre-Antarctica, the vigor, depression, and anger scores of the expeditioners decreased significantly during the austral summer. Notably, the depression score showed a moderate positive correlation with LF/HF, while weak negative correlations with other HRV indicators, including TP, VLF, and LF. Anger score showed a moderate positive correlation with LF/HF and weak negative correlations with the average normal-to-normal (NN) interval, and the root mean square of differences between adjacent RR intervals (RMSSD). Plasma E level weakly correlated with the average NN interval.

CONCLUSION

Prolonged residence in Antarctica increased the ANS activities and shifted the cardiac autonomic modulation towards vagal predominance. The alteration of HRV correlated with mood states and plasma epinephrine levels.

From Social Stress and Isolation to Autonomic Nervous System Dysregulation in Suicidal Behavior

PURPOSE OF REVIEW

In this narrative review we wanted to describe the relationship of autonomic nervous system activity with social environment and suicidal spectrum behaviors.

RECENT FINDINGS

Patients with suicidal ideation/suicide attempt have higher sympathetic nervous system (SNS) and lower parasympathetic nervous system (PNS) activity in resting conditions and during acute stress tasks compared with patients without suicidal ideation/suicide attempt. Death by suicide and violent suicide attempt also are related to SNS hyperactivation. Similarly, a SNS/PNS imbalance has been observed in people with childhood trauma, stressful life events or feelings of loneliness and isolation. Social support seems to increase PNS control and resilience. Due to the importance of the social context and stressful life events in suicidal behavior, SNS/PNS imbalance could act as a mediator in this relationship and be a source of relevant biomarkers. Childhood trauma and stressful life events may impair the autonomic nervous system response in suicidal patients. Loneliness, isolation and social support may act as moderators in acute stress situations.

Effects of workday characteristics and job demands on recovery from work among Finnish home care nurses: a multi-source cross-sectional study

OBJECTIVE

Ageing populations and poor care workforce availability are causing increasing job demands for home care nurses across Europe. While recovery from work helps sustain work ability and wellbeing, past research has relied mainly on self-reported measures of health, stressors, and recovery. This study aims to examine how objective and subjective job demands are associated with measured day-time recovery among home care nurses.

METHODS

Heart rate variability recording was conducted for 95 Finnish home care nurses. The study participants documented their work tasks throughout the workday and filled a wellbeing questionnaire. The amount of care time, breaktime, number of different weekly clients, and their care needs were obtained from the survey. The associations between job demands and measured day-time recovery were analysed using multivariate linear regression.

RESULTS

The amount of day-time recovery was on average 75 min. The number of different clients during the workday (e.g., care continuity) and higher care needs of the clients were associated with lower day-time recovery. Additionally, something slightly disrupting the course of the workday was associated with increased recovery.

CONCLUSIONS

Our findings indicate that reducing especially the objective job demands (workday characteristics) can contribute to better day-time recovery among home care nurses. To help sustain work ability and improve wellbeing, day-time recovery can be promoted with better work scheduling that supports care continuity and ensures sufficient care resources and support for nurses with many clients or clients with high care needs.

Heart rate variability status at rest in adult depressed patients: a systematic review and meta-analysis

Purposes

A meta-analysis was conducted to examine the differences in heart rate variability (HRV) between depressed patients and healthy individuals, with the purpose of providing a theoretical basis for the diagnosis of depression and the prevention of cardiovascular diseases.

Methods

To search China National Knowledge Infrastructure (CNKI), WanFang, VIP, PubMed, Web of Science, Science Direct, and Cochrane Library databases to collect case-control studies on HRV in depressed patients, the retrieval date is from the establishment of the database to December 2022. Effective Public Health Practice Project (EPHPP) scale was used to evaluate literature quality, and Stata14.0 software was used for meta-analysis.

Results

This study comprised of 43 papers, 22 written in Chinese and 21 in English, that included 2,359 subjects in the depression group and 3,547 in the healthy control group. Meta-analysis results showed that compared with the healthy control group, patients with depression had lower SDNN [Hedges' g = -0.87, 95% CI (-1.14, -0.60), Z = -6.254, p < 0.01], RMSSD [Hedges' g = -0.51, 95% CI (-0.69,-0.33), Z = -5.525, p < 0.01], PNN50 [Hedges' g = -0.43, 95% CI (-0.59, -0.27), Z = -5.245, p < 0.01], LF [Hedges' g = -0.34, 95% CI (-0.55, - 0.13), Z = -3.104, p < 0.01], and HF [Hedges' g = -0.51, 95% CI (-0.69, -0.33), Z = -5.669 p < 0.01], and LF/HF [Hedges' g = -0.05, 95% CI (-0.27, 0.18), Z = -0.410, p = 0.682] showed no significant difference.

Conclusion

This research revealed that HRV measures of depressed individuals were lower than those of the healthy population, except for LF/HF, suggesting that people with depression may be more at risk of cardiovascular diseases than the healthy population.

Physical Activity in Long COVID: A Comparative Study of Exercise Rehabilitation Benefits in Patients with Long COVID, Coronary Artery Disease and Fibromyalgia

Exercise in long COVID is poorly studied. Nevertheless, exerciserehabilitation could improve cardiorespiratory, muscular and autonomic functions. We aimed to investigate improvement in physical and autonomic performances of long COVID patients (n = 38) after a 4-week exercise rehabilitation program (3 sessions/week) compared to two control groups composed of coronary artery disease (n = 38) and fibromyalgia patients (n = 38), two populations for whom exercise benefits are well known. Efficacy of exercise training was assessed by a cardiopulmonary exercise test, a handgrip force test, and a supine heart rate variability recording at rest before and after the rehabilitation program. Cardiorespiratory and muscular parameters were enhanced after exercise rehabilitation in the three groups (p < 0.001). No significant difference was observed for the autonomic variables. Through this comparative study with control groups, we confirm and reinforce the interest of caring for long COVID patients without post-exertional symptom exacerbation by exercise rehabilitation of both strength and endurance training, by personalizing the program to the patient and symptoms.

Behavioral and Biological Indicators of Risk and Well-Being in a Sample of South African Youth

Self report measures have been widely used in research to illustrate high rates of exposure to violence among youth in trauma-saturated regions, such as Cape Town, South Africa. To better understand the risk and resilience factors of youth who have been exposed to, witnessed, or directly experienced violence, the current study used a multi-method assessment in a naturalistic setting that included heart rate variability (an index of regulatory flexibility and cardiovascular health), a computerized risk-taking task, and self report measures. Youth (N = 83) from Cape Town, South Africa, participated in a psychobiological assessment. Findings suggest elevated age-adjusted heart rate variability compared to age related norms, which is indicative of overregulation of behavior and emotion. Additionally, youth, all of whom had witnessed or experienced violence at least once, demonstrated a low risk taking and reward seeking propensity. Low risk taking in the context of elevated heart rate variability may reflect youth's affective and behavioral inhibition, suggestive of stress among children who have an overgeneralized threat response. These results both demonstrate the feasibility of psychophysiological research in community youth settings, and counter the traditional narrative that there is an overarching lack of capacity to regulate and a high propensity to risk in violence-exposed youth.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40653-021-00426-1.

Impact of repeated morning bright white light exposures on attention in a simulated office environment

Attention is essential to the work. This study investigated the effects of two different light pulses on a simple attention task. In addition, the effects of subsequent exposure to constant but different illuminance levels on the continuation of the simple attention task and a subsequent complex attention task were examined. A total of 56 subjects were assigned in random order to two white light interventions that were repeated five times during the morning. Each light intervention consisted of a brief light pulse followed by constant light exposure and differed in temporal dimming dynamics and corneal illuminance. Subjective and psychometric parameters were recorded several times during light exposure. Heart rate variability (HRV) was derived from continuous electrocardiograms. Subjects showed improved reaction speed in the simple attention task, accompanied by higher HRV under a brighter light pulse without habituation by repetition. This difference in simple attention performance disappeared when light exposure remained the same after the light pulse. In addition, higher reaction speed and HRV were observed in the complex attention task under constant bright light exposure. Intermittent bright light seems promising to acutely improve attentional performance in office workplaces. Future research is needed to investigate daytime light effects on other work-related cognitive functions.

Beliefs in Regulating Negative Emotions and Vagally Mediated Heart Rate Variability: Does Sex Make a Difference?

OBJECTIVE

This ecological study explored the association between regulatory emotional self-efficacy beliefs in managing negative emotions (RESE-NE) and heart rate variability (HRV), a measure of parasympathetic modulation of the heart that has been positively associated with a better ability to flexibly adjust to a changing environment and regulate emotions.

METHOD

To test these associations, we used data from 161 adults working in relational professions (about 40% men; mean [standard deviation] age = 40.45 [14.17] years) whose HRV was assessed continuously for 24 hours.

RESULTS

Individuals high in RESE-NE showed increased HRV levels ( β = -0.05, p = .011). However, this effect was moderated by biological sex ( β = -0.18, p = .0001) such that RESE-NE positively and significantly predicted HRV for men ( β = 0.18, p < .0001) but not for women ( β = -0.001, p = .989).

CONCLUSIONS

All in all, our study provides initial empirical support for the theoretical expectation derived from social cognitive theory that RESE-NE is positively correlated with a physiological indicator of adaptability to the environmental demands. This was true only for men, likely because of sex differences in physiological stress reactivity and regulation.

Heart Rate Variability at Rest Predicts Heart Response to Simulated Diving

A characteristic feature of the cardiac response to diving is the uncertainty in predicting individual course. The aim of the study was to determine whether resting regulatory heart rate determinants assessed before diving may be predictors of cardiac response in a simulated diving test. The research was conducted with 65 healthy volunteers (37 women and 28 men) with an average age of 21.13 years (20-27 years) and a BMI of 21.49 kg/m² (16.60-28.98). The simulated diving test consisted of stopping breathing after maximum inhaling and voluntarily immersing the face in water (8-10 °C) for as long as possible. The measurements included heart rate variability (HRV) analysis before diving and determination of the course of the cardiac response to diving-minimum and maximum heart rate (HR). The results indicate that minimum HR during diving (MIN_div) is dependent on the short-term HRV measures, which proves the strong influence of the parasympathetic system on the MIN_div. The lack of dependence of MIN_div on short-term HRV in women may be associated with differences in neurogenic HR regulation in women and men. In conclusion, cardiac response to simulated diving is strictly dependent on the autonomic regulation of the heart rhythm under resting conditions. The course of the cardiac response to diving and its relationship with resting HRV appears to be gender dependent.

The effect of extended shift work on autonomic function in occupational settings: A systematic review and meta-analysis

OBJECTIVE

To examine the effect of 24-h shift work on autonomic nervous system function via heart rate variability (HRV) methodologies.

METHODS

Electronic databases (indexed in either PubMed, MEDLINE, CINAHL, SPORTDiscus, or OpenDissertations) were searched from January 1964 to March 2023. A modified Downs and Black checklist was used for assessing methodological quality and the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the quality of evidence. Study design, study population, study sample, shift work description, and assessment of HRV metrics and methods were extracted from each study.

FINDINGS

A total of 58 478 study articles were identified, of which 12 articles met inclusion criteria. Sample sizes varied from eight to 60 participants, with the ratio of low- to high-frequency HRV (LF/HF) as the most common frequency-domain variable reported. Of the nine included studies that observed LF/HF, three (33.3%) demonstrated a significant increase after 24-h shift work. Moreover, of the five studies that reported HF, two (40%) noted a significant decrease after 24-h shift work. When observing risk of bias, two (16.6%) studies were low quality, five (41.7%) were moderate quality, and five (41.7%) were high quality.

INTERPRETATION

There were inconsistent findings demonstrating an effect of 24-h shift work on autonomic function, with a suggested shift away from parasympathetic dominance. Discrepancies in HRV methodologies, such as the duration of recordings and hardware used for measurement, may have contributed to the disparity in findings. In addition, differences in roles and responsibilities across occupations may explain the incongruence in findings across studies.

Estimating Physical/Mental Health Condition Using Heart Rate Data from a Wearable Device

We propose an estimation method of subjects' physical/mental health condition from their heart rate (HR) and evaluate it on the newly collected data including 25 million points over 97 participants. The accurate health condition estimation is important for an employee's mental health care and an objective understanding of our condition. For the estimation, the heart rate variability (HRV) has been widely used, but there are some technical difficulties with measuring the HRV, such as maintaining a good quality of data for a long period of time. Here, we predict the subjects' physical/mental health only from the HR measured by Fitbit instead of the HRV. We first measured more than 25 million points of HR and steps data from 97 participants over 3 months using the Fitbit Inspire HR^TM. We also conducted questionnaires to check their physical conditions each day. We then predict their condition by focusing on the inactive period of HR and applying the support vector machine to the preprocessed data. The best balanced accuracy of our method achieved 0.582, which was higher than the state-of-the-art method with HRV whose accuracy is 0.565.

Acute Physiological Response of Live-Fire Simulation Activities Affecting Cardiovascular Health in Live-Fire Instructors: A Randomized Controlled Simulation Study

OBJECTIVES

This study aimed to assess acute physiological response of fire suppression simulation affecting cardiovascular health during repeated bouts of simulation.

METHODS

Fifteen live-fire instructors were randomly divided into three groups according to fire suppression simulation frequency. Vital signs, biomarkers, and heart rate variability (HRV) were measured before and after simulation.

RESULTS

Vital signs increased immediately after fire simulation and returned to the normal range after 2 h. Most biomarker levels were changed within the normal ranges 72 h after the simulation training. However, one of the HRV frequency domains, high frequency power, was severely suppressed after 1 h and tended to recover after 2 h of simulation (P < 0.05).

CONCLUSIONS

Vital signs and their biomarkers were changed within the normal range regardless of the number of bouts of fire suppression simulations. HRV could be used to assess the effects of fire suppression simulation on cardiovascular health.

Heart Rate Variability in Different Levels of Burnout-Cross-Sectional Study of Different Occupational Groups Heart Rate Variability and Burnout

OBJECTIVES

The aim of this study was a subjective and objective stress analysis of occupational groups.

METHODS

The study examined 414 employees with patients or children contact on work. The age ranged from 22 to 63 years. Subjective stress was measured using the Maslach Burnout Inventory and objective stress with heart rate variability (HRV).

RESULTS

Twenty-one percent of subjects showed a high level of exhaustion, 12.9% a high level of cynicism and low performance. There were significant group differences between cynicism levels in meanNN (P = .008) and meanHR (P = .002). There were no significant differences in HRV for exhaustion and professional efficacy.

CONCLUSIONS

The health-impairing manifestations of the three dimensions of the burnout syndrome are not associated with the lower HRV. However, healthy subjects from a "screening" study who had not been clinically diagnosed with burnout were examined here.

Subjective and objective demands on different types of differential stress inventory

PURPOSE

To validate the differential stress inventory (DSI) by evaluating the objective and subjective stress differences in the five DSI types in the occupational setting.

METHODS

A total of 119 German participants working as medical assistants (n = 40) or in a bank (n = 79) were recruited. They completed the Maslach Burnout Inventory-General Survey, the DSI, and wore ECG measuring devices for 24 h to measure heart rate variability. The DSI was used to group people into one of five types according to how they perceived and coped with stress: normal, overstressed, stress-resistant, low stress/high coping, or high stress/high coping.

RESULTS

The overstressed type had significantly more burnout symptoms than the other types. The high stress/high coping type also had more symptoms of emotional exhaustion and total burnout compared to the other types, while the low stress/high coping and the stress-resistant types generally had the lowest levels of burnout. There were no differences on the HRV parameters among the DSI types.

CONCLUSION

Categorising people into types like in the DSI can help make workers aware of unhealthy stress and coping patterns before they turn into more severe pathology. Proper application and targeted preventive measures can save the individual's health and the company's budget. While the DSI picked up on differences in burnout symptoms as a long-term consequence of stress, there is evidence that it cannot pick up on short-term stress or physical stress as measured by HRV from the 24 h recording.

Investigating the relationship between emotional granularity and cardiorespiratory physiological activity in daily life

Emotional granularity describes the ability to create emotional experiences that are precise and context-specific. Despite growing evidence of a link between emotional granularity and mental health, the physiological correlates of granularity have been under-investigated. This study explored the relationship between granularity and cardiorespiratory physiological activity in everyday life, with particular reference to the role of respiratory sinus arrhythmia (RSA), an estimate of vagal influence on the heart often associated with positive mental and physical health outcomes. Participants completed a physiologically triggered experience-sampling protocol including ambulatory recording of electrocardiogram, impedance cardiogram, movement, and posture. At each prompt, participants generated emotion labels to describe their current experience. In an end-of-day survey, participants elaborated on each prompt by rating the intensity of their experience on a standard set of emotion adjectives. Consistent with our hypotheses, individuals with higher granularity exhibited a larger number of distinct patterns of physiological activity during seated rest, and more situationally precise patterns of activity during emotional events: granularity was positively correlated with the number of clusters of cardiorespiratory physiological activity discovered in seated rest data, as well as with the performance of classifiers trained on event-related changes in physiological activity. Granularity was also positively associated with RSA during seated rest periods, although this relationship did not reach significance in this sample. These findings are consistent with constructionist accounts of emotion that propose concepts as a key mechanism underlying individual differences in emotional experience, physiological regulation, and physical health.

24 h-Heart Rate Variability as a Communication Tool for a Personalized Psychosomatic Consultation in Occupational Health

New tools for non-specific primary prevention strategies covering somatic and mental health in occupational medicine are urgently needed. Heart rate variability (HRV) reflects the capacity of the body to adapt to environmental challenges and of the mind to regulate emotions. Hence, a 24 h-measurement of HRV offers a unique possibility to quantify the interaction between situation-specific emotional regulation within a specific psychosocial environment and physiological state, thereby increasing self-perception and inducing motivation to change behavior. The focus of the present study represents such a 24 h-measurement of HRV and its presentation as a comprehensive graph including protocol situations of the client. A special training program for occupational health physicians and questionnaires for clients were developed and administered. The article reports the first data of the study "healthy leadership and work - body signals for managers and employees", an investigator-initiated, interventional, single-arm, open (non-blinded), multicenter, national trial with 168 participants. They reported a significantly improved perception of their bodily needs after the consultation (from Median = 7, interquartile range 5-8 to Median = 8, interquartile range 7-9; scale range from 1 to 10; p < 0.001, Wilcoxon rank test; effect size 0.49). The 16 occupational health physicians stated that the measurement of HRV was very well suited to enter into dialog with the managers and was feasible to show interactions between situations, thoughts, feelings, and bodily reactions. Taken together, we show that a 24 h-HRV-measurement can be a feasible and effective approach for holistic, psychosomatic primary prevention in occupational medicine. We discuss possible mechanisms for improving the individual health via the consultation, containing mindset and improved ANS activity.

The association between heart rate variability, reaction time, and indicators of workplace fatigue in wildland firefighters

PURPOSE

To understand the association between heart rate variability and indices of fatigue, total sleep time, and reaction time in shift workers.

METHODS

Ten participants from the British Columbia Wildfire Service management team were examined over a 14-day active fire-line period. Daily measures of subjective fatigue, sleepiness, and alertness were recorded using a visual analog scale. Daily total sleep time was recorded using a wrist actigraph. Cardiac autonomic modulation was examined each morning using heart rate variability (HRV). Three measures of reaction time (simple reaction time, choice reaction tie, and discriminatory reaction time) was examined on days 1, 5, 10, and 14. Multiple linear regression analysis was utilized to examine the association between HRV and indices of fatigue, total sleep time, and reaction time.

RESULTS

Mean shift duration was 13.8 ± 0.77 h. Significant inverse associations were observed between HRV and sleepiness [r = - 0.60, p = 0.000] and fatigue [r = - 0.55, p = 0.000], and a positive association with total sleep time (min) [r = 0.28, p = 0.009]. There were no significant relationships between HRV and simple reaction time (ms) [r = - 0.32, p = 0.182], choice reaction time (ms) [r = - 0.10, p = 0.850], or discriminatory reaction time (ms) [r = - 0.09, p = 0.881].

CONCLUSIONS

HRV displayed significant associations with indices of fatigue and sleep, whereby demonstrating its utility as a practical tool for monitoring the development of fatigue in wildland firefighters and for providing insight when to make lifestyle modifications to preserve alertness.

Health outcomes of psychosocial stress within firefighters: A systematic review of the research landscape

BACKGROUND AND OBJECTIVES

Much of the research surrounding firefighter health has concerned the hazards intuitively associated with the occupation, such as physical, thermal, and chemical risks. However, an additional aspect of their work environment, psychosocial stressors, has begun to attract a growing level of attention. Work-related psychosocial stress may best be described as mental and emotional strain caused by a combination of workplace events and characteristics, and the objective of our review was to identify the health outcomes associated with these stressors in firefighters.

METHODS

A systematic review was performed of studies reporting on the psychosocial stressors and the associated health outcomes experienced by firefighters. Data sources included the MEDLINE, PsychInfo, and CINAHL databases.

RESULTS

Twenty-nine studies met the inclusion criteria. Upon analysis, we found that firefighters experienced a range of psychosocial stressors (including interpersonal conflict and concerns over organizational fairness) and observed that these stressors were associated with a number of health-related outcomes that could be arranged into six areas: depression-suicidality, non-depressive mental health problems, burnout, alcohol use disorders, sleep quality, and physiological parameters and somatic disorders.

CONCLUSION

Our findings strongly suggest that work-related psychosocial stressors can affect the health and well-being of those in the fire service, and highlight that interventions meant to address these psychosocial risk factors should focus upon promoting self-esteem, enhancing self-efficacy, and strengthening social support.

Assessment of a dive incident using heart rate variability

INTRODUCTION

Scuba diving likely has an impact on the autonomic nervous system (ANS). In the course of conducting trials of underwater ECG recording for measurement of heart rate variability, there was an unexpected stressful event; one participant's regulator iced and began to free-flow.

METHODS

A custom-made, water- and pressure-tight aluminum housing was used to protect a portable Holter monitor. ECGs were recorded in three experienced divers who witnessed an unplanned moderately stressful incident during diving. The ECG signals were analysed for measures of heart rate variability (HRV).

RESULTS

Analysis for different short-term HRV measures provided consistent results if periods of interest were appropriately time-aligned. There was improvement in sympatho-vagal balance. One diver unexpectedly exhibited an increase in both sympathetic and vagal activity shortly after the incident.

CONCLUSIONS

A conventional open-water dive affected the ANS of experienced recreational divers as measured by HRV which provides a global evaluation of the ANS and alterations in its two branches. The heart rate variability data gathered from several participating divers around the time of this event illustrate the potential utility of this variable in quantifying stress during diving. HRV data may be useful in addressing relevant diving related questions such as effects of cold, exercise or different breathing gases on ANS function.

[Disturbances of Autonomic Regulation of Cardiovascular System at Different Working Regimes with Night Shifts]

Aim        To study temporal and spectral characteristics of heart rhythm variability (HRV) in night shift workers.Materials and methods       Along with traditional risk factors, conditions of labor contribute to development of cardiovascular morbidity, including night shift work, which can be associated with disorders of the autonomic regulation detected by analysis of HRV. This study included 100 healthy men. 74 of them were engaged in shift work, including 53 men with rotating shift work, 21 men with fixed night shifts, and 26 men with day-time work. HRV was analyzed by data of 5-min electrocardiogram recording (background recording and orthostatic test).Results   Night-shift workers had decreases in total power of regulation (ТР, SDNN) and in the parasympathetic branch (HF, pNN50). Rotating night-shift workers displayed significant decreases in SDNN and pNN50 and pronounced changes in the VLF / LF / HF ratio in the orthostatic test.Conclusion            In work with night shifts, the type of autonomic regulation differs from the "standard" functioning of the autonomic nervous system (ANS). This study showed different effects of night work regimens on HRV indexes. With the rotating shift work, the ANS dysregulation was more profound and was evident by a significant decrease in the ANS total tone and parasympathetic activity (SDNN, pNN50) compared to night shifts with fixed working hours. The excessive weakening of the parasympathetic component in the passive orthostatic test can be considered as an early marker for ANS maladaptation.

Prediction of Stress and Mental Workload during Police Academy Training Using Ultra-Short-Term Heart Rate Variability and Breathing Analysis

Heart rate variability (HRV) has been studied in the context of human behavior analysis and many features have been extracted from the inter-beat interval (RR) time series and tested as correlates of constructs such as mental workload, stress and anxiety. Such constructs are crucial in assessing quality-of-life of individuals, as well as their overall performance when doing critical tasks. Most studies, however, have been conducted in controlled laboratory environments with artificially-induced psychological responses. While this assures that high quality data are collected, the amount of data is limited and the transferability of the findings to more ecologically-appropriate settings remains unknown. Additionally, it is desirable for such mental state monitoring systems to have high temporal resolution, thus allowing for quick feedback and adaptive decision making. In this article, we explore the use of features computed from time windows much shorter than typically reported in the literature. More specifically, we evaluate the potential of HRV and breathing features computed over so-called ultra-short-term segments (i.e., < 5 minutes) for stress and mental workload prediction. Experiments with 27 police academy trainees show that short time windows as low as 60 seconds can provide useful insights, in particular for mental workload assessment. Moreover, the fusion of HRV and breathing features showed to be an important aspect for reliable behavioural assessment in highly ecological settings.

Shift Workers at Risk for Metabolic Syndrome

In this highly digitalized era, sleep disorders are becoming more common and are associated with an increased burden of chronic disease. Shift workers are at an increased risk for both sleep disorders and metabolic syndrome. In this article, the authors outline the connection between circadian discordance, hormonal imbalance, and the development of metabolic syndrome in shift workers. Based on a literature review of animal model studies, observational studies, and clinical trials conducted between August and October of 2018, the authors offer several clinical interventions, including work schedules, light therapy, medications, and dietary habits to improve the circadian synchronicity of shift workers and reduce their risk of morbidity and mortality. It is important for physicians to be familiar with the consequences of shift work and ways to mitigate the risks for this patient population.

Towards Intelligent Data Analytics: A Case Study in Driver Cognitive Load Classification

One debatable issue in traffic safety research is that the cognitive load by secondary tasks reduces primary task performance, i.e., driving. In this paper, the study adopted a version of the n-back task as a cognitively loading secondary task on the primary task, i.e., driving; where drivers drove in three different simulated driving scenarios. This paper has taken a multimodal approach to perform 'intelligent multivariate data analytics' based on machine learning (ML). Here, the k-nearest neighbour (k-NN), support vector machine (SVM), and random forest (RF) are used for driver cognitive load classification. Moreover, physiological measures have proven to be sophisticated in cognitive load identification, yet it suffers from confounding factors and noise. Therefore, this work uses multi-component signals, i.e., physiological measures and vehicular features to overcome that problem. Both multiclass and binary classifications have been performed to distinguish normal driving from cognitive load tasks. To identify the optimal feature set, two feature selection algorithms, i.e., sequential forward floating selection (SFFS) and random forest have been applied where out of 323 features, a subset of 42 features has been selected as the best feature subset. For the classification, RF has shown better performance with F1-score of 0.75 and 0.80 than two other algorithms. Moreover, the result shows that using multicomponent features classifiers could classify better than using features from a single source.

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.

Physiological responses during paramedics' simulated driving tasks

BACKGROUND

Most ambulance collisions happen in emergency driving conditions and are caused by human factors.

OBJECTIVE

This study investigated the influence of human factors associated with time pressure, patient-care intervention, and health status on the physiological responses of simulated emergency driving tasks.

METHODS

A cohort of seventeen experienced paramedics performed a battery of three simulated diving tasks. The driving tasks were a non-urgent and two urgent driving simulations (one to the scene and one to the hospital). The second urgent driving task was preceded by a patient-care simulation (unstable cardiac patient with cardiopulmonary resuscitation).

RESULTS

The physiological responses between the three driving tasks were not significantly different due to time pressure and patient-care intervention. It is postulated that the physiological response of experienced paramedics was influenced by the fact that they are accustomed to handling stressful situations daily. Furthermore, it was observed that paramedics with health conditions were more physiologically aroused during the urgent driving scenarios (pre and post-intervention), suggesting they might have an elevated risk of collision when they drive with urgency. Paramedics with health conditions also had higher physiological responses for the post-intervention baseline, leading to a longer recovery time period, which might represent an elevated risk of developing chronic health problems or amplifying existing ones.

CONCLUSIONS

The findings of this research suggest that experienced paramedics manage the influence of time pressure and the impact of challenging patient-care well. Paramedics with health conditions represent an elevated risk of collision.

Heart Rate Variability and Accelerometry as Classification Tools for Monitoring Perceived Stress Levels-A Pilot Study on Firefighters

Chronic stress is the main cause of health problems in high-risk jobs. Wearable sensors can become an ecologically valid method of stress level assessment in real-life applications. We sought to determine a non-invasive technique for objective stress monitoring. Data were collected from firefighters during 24-h shifts using sensor belts equipped with a dry-lead electrocardiograph (ECG) and a three-axial accelerometer. Levels of stress experienced during fire incidents were evaluated via a brief self-assessment questionnaire. Types of physical activity were distinguished basing on accelerometer readings, and heart rate variability (HRV) time series were segmented accordingly into corresponding fragments. Those segments were classified as stress/no-stress conditions. Receiver Operating Characteristic (ROC) analysis showed true positive classification as stress condition for 15% of incidents (while maintaining almost zero False Positive Rate), which parallels the amount of truly stressful incidents reported in the questionnaires. These results show a firm correspondence between the perceived stress level and physiological data. Psychophysiological measurements are reliable indicators of stress even in ecological settings and appear promising for chronic stress monitoring in high-risk jobs, such as firefighting.

Physiologic and behavioural signs during a dental appointment in children and teenagers with Cerebral Palsy: a comparative cross-sectional study

AIM

To evaluate the heart rate (HR) and behaviour of children and teenagers with Cerebral Palsy (CP) when having a dental appointment.

METHODS

A comparative cross-sectional study was carried out with 60 participants with CP, between 2 and 14 years old (study group-SG), and 60 normotypical individuals (CG). The sample was paired according to age, gender and socioeconomic status. Behaviour was evaluated during dental prophylaxis using the Frankl Scale, and HR was measured at five moments: before the appointment, when sitting in the dental chair, during the clinical examination, during prophylaxis and immediately after prophylaxis. Mann-Whitney, Friedman and Chi-square tests were applied at a significance level of 5%.

RESULTS

SG presented significantly higher HR (p < 0.001) and more participants with uncooperative behaviour (p < 0.001) than CG in all observational periods. Furthermore, SG participants with uncooperative behaviour presented higher HR values than those in SG who were cooperative in all observational periods (p ≤ 0.002).

CONCLUSIONS

Individuals with CP have a higher HR before and during the clinical session, and are frequently more uncooperative with the procedure than normotypical individuals.

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.

Stress and Anxiety Measurement "In-the-Wild" Using Quality-aware Multi-scale HRV Features

Heart rate variability (HRV) has been studied in the context of human behavior analysis and many features have been extracted from the inter-beat interval (RR) time series and tested as correlates of constructs such as mental workload, stress and anxiety. Most studies, however, have been conducted in controlled laboratory environments with artificially-induced psychological responses. While this assures that high quality data are collected, the amount of data is limited and the transferability of the findings to more ecologically-appropriate settings (i.e., "in-the-wild") remains unknown. In this paper, we explore the use of motif-based multi-scale HRV features to predict anxiety and stress in-the-wild. To further improve their robustness to artifacts, we propose a quality-aware feature aggregation method. The new quality-aware features are tested on a dataset collected using a wearable biometric sensor from over 200 hospital workers (nurses and staff) during their work shifts. Results show improved stress/anxiety measurement over using conventional time- and frequency-domain HRV measures.

A Comparative Study of Stress and Anxiety Estimation in Ecological Settings Using a Smart-shirt and a Smart-bracelet

In recent years, consumer wearable devices focused on health assessment have gained popularity. Of these devices, a large number target monitoring heart rate; a few among them include additional biometrics such as breathing rate, galvanic skin response, and skin temperature. Heart rate, and more specifically, heart rate variability (HRV) measures have proven useful in monitoring user psychological states, such as mental workload, stress and anxiety. Most studies, however, have been conducted in controlled laboratory environments with artificially-induced psychological responses. While these conditions assure high quality in the collected data, the amount of data are limited and the generalization of the findings to more ecologically-appropriate settings remains unknown. To this end, in this paper we compare the accuracy of two wearable devices, namely a smart-shirt measuring electrocardiograms and a smart-bracelet measuring photoplethysmograms. Several HRV features are extracted and tested as correlates of stress and anxiety. Data were collected from 196 participants during their normal work shifts for a period of 10 weeks. The complementarity of the two devices is also explored and the advantages of each method are discussed.

Indexes of cardiac autonomic profile detected with short term Holter ECG in health care shift workers: a cross sectional study

Background:

The assessment of early effect of shift work-related circadian rhythms desynchronization and work-related stress in health care workers has gained a primary role among the duties of the occupational physician.

Objectives:

Aim of our study was to assess the cardiac autonomic modulation through quantification of sinus rhythm variability, as an index of the adaptability to shift work of the cardiovascular system in healthcare shift workers.

Methods:

We measured Heart Rate Variability (HRV) by short-term (60 minutes) Holter Electrocardiography (ECG) during the regular duties in the respective department of 42 healthcare workers (31 nurses and 11 physicians) of an Italian Hospital (12 male and 30 females, aged 24-58 years), working on 3 shifts with a forward fast rotation with rest at the end of the night shift (7 am - 2 pm; 2 pm - 10 pm; 10 pm - 7 am) or in a fixed daytime shift (8 am - 2 pm). Measurements were all performed between 9 am and 12 am for fixed day workers and between 9 am and 12 pm or between 10 pm and 1 am for shift workers. The following HRV parameters were compared between the subgroups of shift workers and daytime workers: mean heart rate (HR), standard deviation of all normal RR (NN) intervals (SDNN), standard deviation of the averages of NN intervals in all 5-minute segments of a recording (SDaNN) and the triangular index (the integral of the density distribution divided by the maximum of the density distribution). We used parametric tests for independent series to compare HRV parameters by subgroups within the study subjects. We also tested correlation between the variables of interest and the association between HRV and shift work modality, along with other covariates, by means of a multiple linear regression analysis.

Results:

We found significantly lower values of SDaNN in shift workers compared with workers engaged solely on day shifts (50.80 ms vs 66.71 ms; p=0,014). The mean heart rate did not show any significant difference between day workers and shift workers (85.78 bmp vs 85.53 bpm respectively). Multivariate analysis showed a significant association between SDNN and female gender and age, while no significant associations were found between HRV and shift work.

Discussion:

The autonomic control of the heart rhythm could be disrupted by desynchronization of the biological rhythm secondary to the organization of shift work and night work. Shift work is an important factor of social and biological distress, influencing the adaptability of the cardiovascular system to stimuli and demands of work organization.

Effects of nanoparticles exposure and PON1 genotype on heart rate variability

OBJECTIVES

This study was to assess the association between different NPs exposure and PON1 genotype on Heart Rate Variability (HRV) parameters among workers.

METHODS

This study included 235 non-CVD subjects handled to nanomaterials (NM) and 185 non-exposed controls without CVD from 14 NM plants. All participants completed short-term HRV measurements, and were collected blood specimens to measure PON1 activities and the genotype of the PON1 Q192R polymorphism.

RESULTS

In a multivariate regression model, this study observed a positive relationship between nano-Ag exposure and HRV time-domain (RMSSD) and frequency-domain (HF). After adjusting for confounders, the results showed positive associations between RR homozygosity, PON1 paraoxonase/arylesterase activities with HRV, and was particularly noteworthy in RMSSD and HF.

CONCLUSIONS

This study shows a significant increment of RMSSD and HF among workers who handled Nano-Ag materials. These results imply that Nano-Ag and PON1 Q192R genotype can trigger ANS reflexes and alter cardiac frequency and function.

Falk T. Multi-Scale Heart Beat Entropy Measures for Mental Workload Assessment of Ambulant Users

Mental workload assessment is crucial in many real life applications which require constant attention and where imbalance of mental workload resources may cause safety hazards. As such, mental workload and its relationship with heart rate variability (HRV) have been well studied in the literature. However, the majority of the developed models have assumed individuals are not ambulant, thus bypassing the issue of movement-related electrocardiography (ECG) artifacts and changing heart beat dynamics due to physical activity. In this work, multi-scale features for mental workload assessment of ambulatory users is explored. ECG data was sampled from users while they performed different types and levels of physical activity while performing the multi-attribute test battery (MATB-II) task at varying difficulty levels. Proposed features are shown to outperform benchmark ones and further exhibit complementarity when used in combination. Indeed, results show gains over the benchmark HRV measures of 24.41% in accuracy and of 27.97% in F1 score can be achieved even at high activity levels.

Entropy Measures Can Add Novel Information to Reveal How Runners' Heart Rate and Speed Are Regulated by Different Environments

Ecological psychology suggests performer-environment relationship is the appropriate scale for examining the relationship between perception, action and cognition. Developing performance requires variation in practice in order to design the attractor-fluctuation landscape. The present study aimed to identify the effects of varying levels of familiarity and sensorimotor stimuli within the environment in runners' speed and heart rate (HR) regularity degree, and short-term memory Twelve amateur runners accomplished three 45-min running trials in their usual route, in an unusual route, and an athletics 400-m track, wearing a GPS and an HR monitor. Sample entropy (SampEn) and complexity index (CI), over speed and HR, were calculated. Pre and post-trial, participants performed the Backward Digit Span task for cognitive assessment. Higher entropies were found for the 400-m track, compared to the usual and unusual routes. Usual routes increased speed SampEn (63% of chances), but decreased HR CI when compared to unusual routes (60% of chances). Runners showed higher overall short-term memory performance after unusual routes, when compared to usual routes (85% of chances), indicating positive relation to attentional control. The contexts of practice may contribute to change predictability from single to multiple timescales. Thus, by considering that time structuring issues can help diagnosing habituation of training routes, this study brings novel information to the long-term process of training.

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.

Shiftwork Association with Cardiovascular Diseases and Cancers Among Healthcare Workers: A Literature Review

The round-the-clock demands of healthcare services, coupled with the shortage of healthcare providers in many parts of the world, have made shiftwork widespread among healthcare workers. Understanding how to mitigate unfavourable effects of shiftwork on well-being is essential to improve health promotion, to prevent disease prevention, and to increase quality of life. This comprehensive review aims to present evidence linking shiftwork with cardiovascular diseases and cancers among healthcare workers. Several studies have demonstrated evidence indicating the relationship between long-term exposure to shiftwork tempo and a higher risk of cardiovascular diseases. Health workers are increasingly witnesing unfavourable effects of shiftwork on their health state. Shiftwork disturbs circadian rhythm and cardiopulmonary processes, leading to adverse health outcomes. Increasing prevalence of shiftwork in healthcare industries due to population expansion and public health threat of cancers call for investigation towards a better understanding of the underlying mechanism of shiftwork-induced diseases. The shift work period has been considered in different studies using various criteria, resulting in inconsistent definition of measurement criteria leading to misclassification of the study population. There is a need for a more considerable and holistic effort towards standardization of shiftwork definition and conduct an assessment to establish a more conveniently appliacable framework for intervention strategies.

Decreased Parasympathetic Activity of Heart Rate Variability During Anticipation of Night Duty in Anesthesiology Residents

BACKGROUND

In residency programs, it is well known that autonomic regulation is influenced by night duty due to workload stress and sleep deprivation. A less investigated question is the impact on the autonomic nervous system of residents before or when anticipating a night duty shift. In this study, heart rate variability (HRV) was evaluated as a measure of autonomic nervous system regulation.

METHODS

Eight residents in the Department of Anesthesiology were recruited, and 5 minutes of electrocardiography were recorded under 3 different conditions: (1) the morning of a regular work day (baseline); (2) the morning before a night duty shift (anticipating the night duty); and (3) the morning after a night duty shift. HRV parameters in the time and frequency domains were calculated. Repeated measures analysis of variance was performed to compare the HRV parameters among the 3 conditions.

RESULTS

There was a significant decrease of parasympathetic-related HRV measurements (high-frequency power and root mean square of the standard deviation of R-R intervals) in the morning before night duty compared with the regular work day. The mean difference of high-frequency power between the 2 groups was 80.2 ms (95% confidence interval, 14.5-146) and that of root mean square of the standard deviation of R-R intervals was 26 milliseconds (95% confidence interval, 7.2-44.8), with P = .016 and .007, respectively. These results suggest that the decrease of parasympathetic activity is associated with stress related to the condition of anticipating the night duty work. On the other hand, the HRV parameters in the morning after duty were not different from the regular workday.

CONCLUSIONS

The stress of anticipating the night duty work may affect regulation of the autonomic nervous system, mainly manifested as a decrease in parasympathetic activity. The effect of this change on the health of medical personnel deserves our concern.

Assessment of Ocular and Physiological Metrics to Discriminate Flight Phases in Real Light Aircraft

OBJECTIVE

The purpose of the present study was to find psychophysiological proxies that are straightforward to use and could be implemented in actual flight conditions to accurately discriminate pilots' workload levels.

BACKGROUND

Piloting an aircraft is a complex activity where cognitive limitations may jeopardize flight safety. There is a need to implement solutions to monitor pilots' workload level to improve flight safety. There has been recent interest in combining psychophysiological measurements. Most of these studies were conducted in flight simulators at the group level, limiting the interpretation of the results.

METHODS

We conducted an experiment with 11 pilots performing two standard traffic patterns in a light aircraft. Five metrics were derived from their ocular and cardiac activities and were evaluated through three flight phases: takeoff, downwind, and landing.

RESULTS

Statistical analyses showed that the saccadic rate was the most efficient metric to distinguish between the three flight phases. In addition, a classifier trained on the ocular data collected from the first run predicted the flight phase within a second run with an accuracy of 75%. No gain in the classifier accuracy has been found by combining cardiac and ocular metrics.

CONCLUSIONS

Ocular-based metrics may be more suitable than cardiac ones to provide relevant information on pilots' flying activity in operational settings.

APPLICATIONS

Electrocardiographic and eye-tracking devices could be implemented in future cockpits as additional flight data for accident analysis, an objective pilot's state evaluation for training, and proxies for human-machine interactions to improve flight safety.

Fluctuations in heart rate variability of health care workers during four consecutive extended work shifts and recovery during rest and sleep

The aim of this study was to investigate fluctuations in heart rate variability (HRV), which reflect autonomic nervous system (ANS) function and potential psychological and physical strain, among 24 health care workers during work and sleep during four consecutive extended work shifts. Data included 24/36/12 h of HRV measurements, two logbooks, and a questionnaire. A cross-shift/cross-week design was applied. HRV was measured during work, leisure time, and sleep. The HRV data included time-domain [mean RR, SD of normal to normal R-R intervals (SDNN), and root mean square of the successive differences (RMSSD)] and frequency-domain [low frequency (LF)/high frequency (HF) ratio] parameters. HRV parameters revealed significant differences among work, leisure time, and sleep. Mean RR, RMSSD, and SDNN values were lower and the LF/HF ratio was higher on the first versus last day of the work period; however, the differences were most prominent in the morning hours. The results indicate higher levels of cardiovascular stress on the first versus fourth day of the working period, and measurements at night indicate a satisfactory recovery from the extended shifts.

Shift work is associated with reduced heart rate variability among men but not women

BACKGROUND

Imbalance in the autonomic nervous system due to a disrupted circadian rhythm may be a cause of shift work-related cardiovascular diseases.

OBJECTIVE

We aimed to determine the association between shift work and cardiac autonomic activity in blue-collar workers.

METHODS

The study included 665 blue-collar workers aged 18-68 years in different occupations from two Danish cohort studies. Time and frequency domain parameters of heart rate variability (HRV) were measured during sleep using the Actiheart monitor, and used as markers of cardiac autonomic function. Multiple linear regression analyses were used to investigate differences in HRV between day and shift workers.

RESULTS

Shift workers had no significantly different HRV parameters than day workers, except for a lower VLF (B: 0.21; 95% CI: -0.36-0.05). The lower VLF was only present among non-night shift workers (p < 0.05) and not among night shift workers (p > 0.05). Results differed significantly by gender (p for interaction < 0.10): among men, shift work was negatively associated with RMSSD (B: -7.83; 95% CI: -14.28-1.38), SDNN (B: -7.0; 95% CI: -12.27-1.78), VLF (B: -0.27; 95% CI: -0.46-0.09) and Total Power (B: -0.61; 95% CI: -1.20-0.03), while among women, shift work was only associated with the LF/HF ratio (B: -0.29; 95% CI: -0.54-0.03).

CONCLUSION

Shift work was particularly associated with lower HRV during sleep among men. This indicates that shift work causes imbalance in the autonomic nervous system among men, which might increase their risk of cardiovascular diseases.

The chemical disruption of human metabolism

BACKGROUND

Recent evidence highlights the reality of unprecedented human exposure to toxic chemical agents found throughout our environment - in our food and water supply, in the air we breathe, in the products we apply to our skin, in the medical and dental materials placed into our bodies, and even within the confines of the womb. With biomonitoring confirming the widespread bioaccumulation of myriad toxicants among population groups, expanding research continues to explore the pathobiological impact of these agents on human metabolism.

METHODS

This review was prepared by assessing available medical and scientific literature from Medline as well as by reviewing several books, toxicology journals, government publications, and conference proceedings. The format of a traditional integrated review was chosen.

RESULTS

Toxicant exposure and accrual has been linked to numerous biochemical and pathophysiological mechanisms of harm. Some toxicants effect metabolic disruption via multiple mechanisms.

CONCLUSIONS

As a primary causative determinant of chronic disease, toxicant exposures induce metabolic disruption in myriad ways, which consequently result in varied clinical manifestations, which are then categorized by health providers into innumerable diagnoses. Chemical disruption of human metabolism has become an etiological determinant of much illness throughout the lifecycle, from neurodevelopmental abnormalities in-utero to dementia in the elderly.