Mediating effects of hair cortisol on the mutual association of job burnout and insomnia: A retrospective exploratory study

The association between hair cortisol and burnout is moderated by age, psychosocial, and immunological markers

Background

Exhaustion and depersonalization are the core symptoms of the occupational burnout. However, burnout is not an all-or-nothing phenomenon, but can occur in a milder to moderate form in otherwise healthy employees. In the last two decades hair cortisol concentrations (HCC) were increasingly related to the cumulative effect of psychosocial stress at work. We analyzed data of the Dortmund Vital Study (Clinicaltrials.gov: NCT05155397) to explore the relationship of HCC and burnout symptoms. Moreover, we asked whether the HCC - burnout association was moderated by work ability, chronic stress, neuroticism, depressive symptoms, and stress-related immunological biomarkers such as T cell concentration, CD4/CD8 cell ratio, and proinflammatory cytokines TNF- α, IL-6, and IL-18.

Methods

Burnout was assessed by the Oldenburg Burnout Inventory (OLBI), and the Maslach Burnout Inventory (MBI-D) in 196 working adults aged between 20 and 65 years (mean age 42.2 years). Several self-reported variables and biomarkers were collected.

Results

The results showed an association between HCC and the burnout measures. A series of moderator analyses revealed that the association between HCC and burnout symptoms was substantial for low work ability, high chronic stress level, high neuroticism level, and mild to moderate depressive symptoms. Immunological markers moderated the HCC - burnout association for high concentrations of T cells, low CD4/CD8 ratio and low IL-6, IL-18 and TNF-α concentrations. These interactions were moderated by age showing the largest impact in middle-aged to older individuals.

Conclusions

The present findings shed light on the complex interaction between burnout symptoms and work ability, chronic stress, personality, and the endocrinological and immunological responses across the working lifespan. These parameters should be considered when assessing the risk for developing burnout and validating the diagnosis of burnout.

Trial registration

ClinicalTrials.gov NCT05155397; https://clinicaltrials.gov/ct2/show/NCT05155397.

Association between high emotional demand at work, burnout symptoms, and sleep disturbance among Korean workers: a cross-sectional mediation analysis

We explored the mediating role of burnout on the association between EDW and sleep disturbances. Our study included 18,744 Korean workers. Respondents were grouped into four levels (none, low, moderate, and high) based on their exposure to two EDW factors: handling angry clients (HAC) and hiding emotion (HE). Mediation models were used to estimate odds ratios (OR) at a 95% confidence interval (CI). Compared to those not exposed, low, moderate, and high HAC increased odds of sleep disturbance by 1.52 (95% CI 1.30-1.78), 3.20 (95% CI 2.57-3.98), and 3.28 (95% CI 2.77-3.88) times, respectively. The indirect effect via burnout accounted for 29.9%, 24.1%, and 23.6% of the total effect, respectively, with estimates of 1.13 (95% CI 1.11-1.16), 1.32 (95% CI 1.26-1.39), and 1.32 (95% CI 1.27-1.37). Low, moderate, and high HE increased the odds of sleep disturbance by 1.45 (95% CI 0.93-2.28), 2.38 (95% CI 1.57-3.61), and 3.14 (95% CI 2.08-4.71) times, respectively. The indirect effect via burnout accounted for 10.5%, 29.7%, and 33.1% of the total effect, with estimates of 1.04 (95% CI 0.98-1.10), 1.29 (95% CI 1.22-1.37), and 1.46 (95% CI 1.38-1.55), respectively. Effective policies are required to protect the psychological wellbeing of workers who frequently engage in interpersonal tasks.

Hair cortisol concentration associates with insomnia and stress symptoms in breast cancer survivors

Stress, depressive symptoms and sleep quality are important and modifiable determinant of health and their association with hair cortisol concentrations (HCC) in breast cancer survivors has not been evaluated. We selected a random sample of 65 participants (mean age 57.9 years old, range 44-75 years) recruited from local patients' associations of breast cancer survivors. Each provided a hair sample at enrollment and basic clinical data and psychological evaluation regarding self-perceived stress (PSS-scale), depressive (GDS scale) and insomnia symptoms (Athens scale). We observed a direct and significant (p = 0.001) association between HCC and stress-levels. Depressive symptoms associated significantly (p < 0.01) with stress levels but not with HCC. There were also a significant and direct correlation between hair cortisol concentration and totals core of insomnia symptoms (p = 0.002), and the subdimension of sleep difficulty symptoms (p = 0.002), and with daytime sleepiness symptoms (p = 0.016). Further investigations into the association between stress and insomnia and changes in HCC in breast cancer survivors are warranted in order to validate this biomarker for diagnosis of psychological alterations and to tailor the effects of interventions aimed to reduced stress and improve sleep quality in these women.

Association of hair glucocorticoid levels with sleep quality indicators: a pilot study in apparently healthy perimenopausal and menopausal women

Background

Poor sleep quality is associated with different physical and mental health diseases. It is proposed that increased hypothalamic-pituitary-adrenal axis activity is a potential contributor affecting sleep pattern and quality. We aimed to analyze the relationship between subjective sleep quality indicators and hair glucocorticoid levels among relatively healthy perimenopausal and postmenopausal women.

Methods

A total of 145 women aged 50-64 y.o. were enrolled in the cross-sectional pilot study. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index, while stress level was measured using the Perceived Stress Scale. Hair cortisol and cortisone levels were determined by ultra-high-performance liquid chromatography-tandem mass spectrometry.

Results

Statistically significant positive relationship was found between hair cortisol concentration and Pittsburgh sleep quality index score. Similarly, statistically significant positive associations were observed between hair total glucocorticoid level and Pittsburgh sleep quality index, sleep disturbance, and Perceived Stress Scale scores. Subjects with prolonged sleep latency had significantly higher hair cortisol and total hair glucocorticoid concentrations compared with individuals whose sleep latency is not disturbed. Additionally, Chi-squared test indicated that lower hair cortisol concentration was significantly related to better sleep efficiency.

Conclusion

Increased hair glucocorticoid (cortisol, cortisone) levels were found to be related with worse sleep quality measured by Pittsburgh sleep quality index score.

Prevalence of burnout and its relation to the neuroendocrine system among pediatric residents during the early Covid-19 pandemic: A pilot feasibility study

Background

Measuring burnout relies on infrequent and subjective surveys, which often do not reflect the underlying factors or biological mechanisms that promote or prevent it. Burnout correlates with cortisol levels and dysregulation of the hypothalamic-pituitary-adrenal axis, but the chronology and strength of this relationship are unknown.

Objective

To determine the prevalence and feasibility of studying burnout in pediatric residents using hair cortisol and hair oxytocin concentrations.

Design

/Methods: Longitudinal observational cohort study of pediatric residents. We assessed burnout using the Stanford Professional Fulfillment Index and hair cortisol (HCC), and hair oxytocin concentrations (HOC) at four 3-month intervals from January 2020-January 2021. We evaluated test-retest reliability, sensitivity to change using Pearson product-moment correlations, and relationships between burnout and hair biomarkers using hierarchical mixed-effects linear regression.

Results

17 Pediatrics residents provided 78 wellness surveys and 54 hair samples. Burnout symptoms were present in 39 (50%) of the surveys, with 14 (82%) residents reporting burnout in at least one time point. The lowest (41%) and highest (60%) burnout prevalence occurred in 04/2020 and 01/2021, respectively. No significant associations between burnout scores and HCC (β -0.01, 95%CI: 0.14-0.13), HOC (β 0.06, 95%CI: 0.06-0.19), or the HCC:HOC ratio (β -0.04, 95%CI: 0.09-0.02) were noted in separate analyses. Intra-individual changes in hair cortisol concentration were not associated with changes in burnout score.

Conclusions

Burnout was prevalent among Pediatrics residents, with highest prevalence noted in January 2021. This pilot longitudinal study demonstrates the feasibility of evaluating burnout with stress and resilience biomarkers in Pediatrics residents.

Investigation of cross-sectional and longitudinal associations between work-related burnout and hair cortisol: The Regensburg Burnout Project

BACKGROUND

Burnout is characterized by feelings of exhaustion, depersonalization as well as reduced personal accomplishment and is linked to various negative health effects. Previous studies on biological correlates of burnout have focused on the hypothalamic-pituitary-adrenal (HPA) axis. However, especially studies on hair cortisol concentrations (HCC) were often based on cross-sectional data and yielded inconsistent results, probably due to the heterogeneity of the selected samples. Accordingly, the aim of the present study was to investigate cross-sectional as well as longitudinal associations between burnout and HCC within a sample consisting of a strictly specified group of individuals suffering from burnout (BO group) and a healthy comparison group (HC group).

METHODS

After a multi-stage recruitment procedure based on burnout symptoms and pathogenesis, eligible subjects (out of an initial sample of 1022 volunteers) were assigned either to a BO (n = 55) or HC group (n = 59), as described in detail in Bärtl et al. (2022). Burnout symptoms as well as HCC (1 cm hair samples) were measured repeatedly at two sampling time points t1 (n = 114) and t2 (n = 100) with an interval of M = 7.20 months (SD = 1.16) between assessments.

RESULTS

In the total study sample, no cross-sectional associations between burnout and HCC were found either at t1 or at t2. When the analysis was restricted to the BO group, HCC was positively related to burnout symptomatology at t1 but not t2. In the longitudinal analysis, burnout symptoms at t1 were significant negative predictors of HCC at t2. However, the change in HCC from t1 to t2 was not associated with the change in burnout symptoms.

CONCLUSIONS

In the present study, we investigated the association between HCC and burnout in a strictly defined sample of subjects suffering from burnout and healthy controls. Our findings mainly do not support our hypotheses. At least, the positive association between HCC and burnout symptoms only within the BO group supports the idea that HPA axis alterations in burnout might only become apparent once a certain threshold of burnout symptomatology has been exceeded, while the longitudinal data provide some empirical evidence for the potential long-term development of hypocortisolism in burnout. However, respective results remain relatively inconclusive.

Does engagement help to reduce insomnia when workers are emotionally exhausted?

Insomnia is one of the most common problems, affecting more than 35% of the world's population. To achieve a better understanding of this problem the focus of this research is to understand how emotional exhaustion at work may lead to insomnia. To help to combat it, we tested a mediation model including engagement factors. The sample was composed of 823 participants. 38.3% (315 subjects) were male and 61.7% (508 subjects) were female. Mean age was 42.65 years old (9.05 = SD). Main results showed that emotional exhaustion is directly and statistically significant related to insomnia. However, different engagement factors showed different weights in buffering this relationship. Emotional exhaustion showed a statistically significant impact on insomnia. Vigor and absorption helped to buffer the impact of emotional exhaustion over insomnia. Our study has some limitations. First, the sample was acquired by not aleatory processes. Another limitation is that our sample was composed of individuals with decision-making capacity. Lastly, our research is a transversal study. Future research should take these limitations into account and conduct longitudinal research with aleatory sampling procedures.

Trajectories of Job Burnout among Bus Drivers in China: A Three-Year Follow-Up Study

This study aimed to characterize job burnout in longitudinal trajectories among bus drivers and examine the impact of variables related to job burnout for trajectories. A longitudinal study was conducted in 12,793 bus drivers in Guangdong province, China, at 3-year follow-up assessments. Growth mixture modeling (GMM) was used to estimate latent classes of burnout trajectories and multinomial logistic regression models were applied to predict membership in the trajectory classes. In general, there was a decrease in job burnout in 3 years [slope = -0.29, 95%CI = (-0.32, -0.27)]. Among those sub-dimensions, reduced personal accomplishment accounted for the largest proportion. GMM analysis identified five trajectory groups: (1) moderate-decreased (n = 2870, 23%), (2) low-stable (n = 5062, 39%), (3) rapid-decreased (n = 141, 1%), (4) moderate-increased (n = 1504, 12%), and (5) high-stable (n = 3216, 25%). Multinomial logistic regression estimates showed that depression symptoms, anxiety symptoms, and insomnia were significant negative predictors, while daily physical exercise was a significantly positive predictor. We found an overall downward trend in bus drivers' burnout, particularly in the sub-dimension of personal accomplishment. Mentally healthier drivers and those who were usually exercising were more resilient to occupational stress and less likely to suffer burnout.

Association between burnout and insomnia in U.S. Air Force Pararescue personnel: A cross-sectional study

Studies have examined burnout and its impact on health, to include its influence on sleep. While many studies report a significant relationship between burnout and insomnia in civilian populations, no studies have examined this relationship in a military population. The United States Air Force (USAF) Pararescue personnel are an elite combat force who are specially trained to conduct both first-line combat and full spectrum personnel recovery and may be at high risk of burnout and insomnia. The current study investigated the association between dimensions of burnout and insomnia, and also examined potential moderators of the associations. A cross-sectional survey was administered to 203 Pararescue personnel (Mean Age = 32.1 years; 100% Male; 90.1% Caucasian) recruited from six US bases. The survey included measures of three dimensions of burnout (emotional exhaustion, depersonalization, personal achievement), insomnia, psychological flexibility, and social support. Emotional exhaustion was significantly associated with insomnia with a moderate to large effect size, when controlling for covariates. Depersonalization, but not personal achievement, was also significantly associated with insomnia. There was no evidence that associations between burnout and insomnia were moderated by psychological flexibility or social support. These findings help to identify individuals at risk of insomnia and may ultimately be useful in developing interventions for insomnia in this population.

Cross-sectional relation of long-term glucocorticoids in hair with anthropometric measurements and their possible determinants: A systematic review and meta-analysis

BACKGROUND

Long-term glucocorticoids (HairGC) measured in scalp hair have been associated with body mass index (BMI), waist circumference (WC), and waist-hip-ratio (WHR) in several cross-sectional studies. We aimed to investigate the magnitude, strength, and clinical relevance of these relations across all ages.

METHODS

We performed a systematic review and meta-analysis (PROSPERO registration CRD42020205187) searching for articles relating HairGC to measures of obesity. Main outcomes were bivariate correlation coefficients and unadjusted simple linear regression coefficients relating hair cortisol (HairF) and hair cortisone (HairE) to BMI, WC, and WHR.

RESULTS

We included k = 146 cohorts (n = 34,342 individuals). HairGC were positively related to all anthropometric measurements. The strongest correlation and largest effect size were seen for HairE-WC: pooled correlation 0.18 (95%CI 0.11-0.24; k = 7; n = 3,158; I²  = 45.7%) and pooled regression coefficient 11.0 cm increase in WC per point increase in 10-log-transformed HairE (pg/mg) on liquid-chromatography-(tandem) mass spectrometry (LC-MS) (95%CI 10.1-11.9 cm; k = 6; n = 3,102). Pooled correlation for HairF-BMI was 0.10 (95%CI 0.08-0.13; k = 122; n = 26,527; I²  = 51.2%) and pooled regression coefficient 0.049 kg/m² per point increase in 10-log-transformed HairF (pg/mg) on LC-MS (95%CI 0.045-0.054 kg/m² ; k = 26; n = 11,635).

DISCUSSION

There is a consistent positive association between HairGC and BMI, WC, and WHR, most prominently and clinically relevant for HairE-WC. These findings overall suggest an altered setpoint of the hypothalamic-pituitary-adrenal axis with increasing central adiposity.

Objective light exposure measurements and circadian rhythm in patients with erythropoietic protoporphyria: A case-control study

BACKGROUND

Erythropoietic protoporphyria (EPP) patients suffer from painful phototoxicity. Sunlight-avoiding behaviour has not yet been quantified objectively in EPP patients.

OBJECTIVE

To study total white light exposure obtained with an actigraph device, before and during afamelanotide treatment, in EPP patients compared to healthy controls. Effects on circadian rhythm, pain and sleep were also investigated.

METHODS

Adult EPP patients visiting the Porphyria Center Rotterdam of the Erasmus MC were included in this single-center longitudinal case-control open-label intervention study. Controls were age and place of residence matched. Participants wore an actigraph (Actiwatch Pro) during two weeks for multiple periods. Afamelanotide was given to EPP patients as part of standard care.

RESULTS

Twenty-six EPP patients and 23 matched controls participated. Controls were statistically significantly more exposed to white light than EPP patients off treatment during autumn (95.4%), spring (69.9%), and summer (105.4%; p = 0.01). EPP patients on afamelanotide treatment had 71.6% more light exposure during spring compared to EPP patients off treatment (p < 0.01). Afamelanotide treatment resulted in a reduction of painful moments in the morning (6.5% decrease) and the evening (8.1% decrease; p < 0.05). Bedtime differed between EPP patients off treatment, controls and EPP patients on treatment (23:45 h ± 1:51 versus 23:02 ± 1:41 and 23:14 ± 1:29, respectively; p < 0.0001).

CONCLUSION

Actigraphy is a useful method to objectively measure white light exposure and treatment effects in EPP. In EPP patients afamelanotide treatment is associated with increased white light exposure during spring, and overall less pain. Treatment with afamelanotide is also associated with normalization of circadian rhythm.

Higher Levels of Stress-Related Hair Steroid Hormones Are Associated with the Increased SCORE2 Risk Prediction Algorithm in Apparently Healthy Women

Cardiovascular diseases (CVDs) are the major cause of death worldwide. Although the importance of conventional CVD risk factors, including older age, male gender, hypertension, obesity, dyslipidemia and hyperglycemia, is well-studied, psychosocial stress, which is considered an independent CVD risk factor, requires further investigation. Thus, we aimed to investigate the association between long-term secretion of stress-related steroid hormones, including cortisol, cortisone and dehydroepiandrosterone, and the 10-year fatal and non-fatal CVD risk estimated by the SCORE2 risk prediction algorithm, as well as traditional CVD risk factors in a group of apparently healthy women. A total of 145 women (aged 50–64 years) participating in the national CVD prevention program were enrolled in the study. Sociodemographic, lifestyle, health-related characteristics, stress, anxiety and sleep quality indicators were evaluated using specific questionnaires. Anthropometric and arterial blood pressure measures were assessed by trained personnel, lipid and glucose metabolism biomarkers were measured using routine methods, and hair steroid hormone levels were determined by ultra-high-performance liquid chromatography-tandem mass spectrometry. The results showed that higher levels of hair cortisol and cortisone are associated with increased SCORE2 values. Moreover, significant associations between hair glucocorticoids and individual cardiovascular risk factors, including obesity, hypertension, dyslipidemia and hyperglycemia, were found. These findings indicate that stress-related hair steroid hormones might be valuable biomarkers for CVD prediction and prevention.

Longitudinal associations between hair cortisol, PTSD symptoms, and sleep disturbances in a sample of firefighters with duty-related trauma exposure

Several studies have found evidence of altered cortisol levels in patients with posttraumatic stress disorder (PTSD). Based on these findings, it is assumed that these patients may show signs of cortisol dysregulation after trauma. Posttrauma cortisol levels are thus considered a potential biomarker of PTSD. However, longitudinal studies using indicators of long-term cortisol secretion such as hair cortisol concentrations (HCC) are scarce. The current study investigated prospective associations between HCC and PTSD symptoms in a sample of Dutch firefighters taking into account varying levels of work-related trauma severity. In addition, we assessed posttraumatic sleep disturbances as a secondary outcome measure to investigate whether effects generalize to this frequent comorbidity of PTSD. Three hundred seventy-one Dutch firefighters with a mean of 14.01 years of work experience were included in the analyses. Baseline assessment included the collection of hair samples and the measurement of work-related trauma severity, PTSD symptoms, and sleep disturbances. PTSD symptoms and sleep disturbance were re-assessed after six and twelve months. Multilevel analyses indicate a significant positive correlation between HCC and baseline PTSD symptoms in those with average or above-average work-related trauma severity. A similar pattern was evident for posttraumatic sleep disturbances at baseline. Moreover, higher HCC predicted more posttraumatic sleep disturbances after 6 months in participants with above-average work-related trauma severity. No other associations emerged for PTSD symptoms or posttraumatic sleep disturbances at six or twelve months. As such, our study supports the existence of a cross-sectional association between HCC and trauma symptoms, which may vary for different levels of subjective trauma severity. The longitudinal stability of this association should be reinvestigated by future research.

The moderating effect of cortisol and dehydroepiandrosterone on the relation between sleep and depression or burnout

For poor sleep quality (SQ) as well as major depressive disorder (MDD) and burnout, a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been identified. Although poor SQ is often reported as an early symptom of MDD or burnout, it is not clear whether HPA axis-related hormones can influence the association between SQ and MDD or burnout. This manuscript addresses this question by examining HPA axis-related hormones as potential moderators influencing the association between SQ and MDD or burnout.

In the fourth annual examination wave of the Dresden Burnout Study, we measured general SQ (including sleep duration and efficiency), depressive and burnout symptoms, and obtained hair samples for quantification of long-term integrated steroid concentrations (cortisol [hC], cortisone [hCn], dehydroepiandrosterone [hDHEA]) from 462 participants (67% female). Data on SQ, depressive and burnout symptoms were available from 342 participants from the preceding examination wave (average time span between examinations 13.2 months).

Cross-sectional analyses showed that the negative association between sleep duration and depressive symptoms was buffered by higher levels of hC, and hCn, whereas the negative association between sleep duration and burnout symptoms was buffered by higher levels of hDHEA. The negative association between sleep efficiency and burnout symptoms was intensified by higher levels of hC and hC/hCn ratio and the negative association between general SQ and burnout symptoms was intensified by higher levels of hC/hCn ratio. With regard to longitudinal data, a significant interaction effect between sleep duration and hC/hCn ratio could be detected for burnout symptoms.

Our results suggest opposed moderation effects of hair glucocorticoids on the association between SQ and depressive or burnout symptoms. This points toward opposed glucocorticoid receptor functioning in depression and burnout. To fully elucidate the negative consequences of poor SQ on MDD and burnout, the complex underlying mechanisms of action including HPA axis-related hormones need to be investigated in MDD and burnout separately.

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hC and hDHEA are not directly related to depression, burnout, or sleep symptoms.

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Higher hC levels buffer the relation between poor sleep quality (SQ) and depression.

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Higher hC levels intensify the relation between poor SQ and burnout.

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Higher hDHEA levels buffer the relation between poor SQ and burnout.

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hC and hDHEA exhibit contrary effects on the relation between SQ and burnout.

Salivary cortisol concentrations in hematogy/oncology nurses on working days and days off

OBJECTIVE

to assess salivary cortisol concentrations in hematology/oncology nurses on working days and days off.

METHODS

a cross-sectional study carried out with 28 nurses from a university hospital. A sociodemographic, employment and health profile questionnaire was applied. For saliva collection, Salivette® tubes were used. Descriptive and analytical analysis was used.

RESULTS

there was no significant difference in cortisol concentrations between working days and days off (p>0.05). The high cortisol concentration was associated with not having children (0.621±0.340; p=0.046), not using medication (0.623±0.133; p=0.017) and birth control pills (0.556 ± 0.228; p=0.047) and intention to leave work (0.951±0.154; p=0.001). A positive correlation was identified between cortisol and absence from work due to health issues (0.72; p=0.05) and weight gain (0.935; p=0.02).

CONCLUSION

in general, cortisol concentration is within the reference parameters, with no significant difference in its secretion on working days and days off.

Hair Cortisol Concentration as a Biomarker of Sleep Quality and Related Disorders

Cortisol is the end product of the hypothalamic-pituitary-adrenal (HPA) axis, and its production is increased mainly in stressful situations or in chronic disorders accompanied by stress enhancement. Altered cortisol concentrations have been reported in a number of neuropsychiatric diseases and sleep disorders. Cortisol concentrations have been measured using several methods, and in several matrixes, such as blood, saliva, and urine. However, lately, hair cortisol, for several reasons, has emerged as a promising biomarker of long-term retrospective HPA activation. Several experimental approaches for cortisol measurement with the corresponding concentration reference ranges and a summary of findings from scientific literature on this field are presented. There is evidence of a close relationship between HPA functional alteration and the development of neuropsychiatric disorders. Sleep disorders are the most common manifestation in several neuropsychiatric conditions, and have also been associated to cortisol alterations in both adults and children. Many studies indicate that hair cortisol constitutes a valuable tool for further contributing to existing data on salivary, plasma, or urinary cortisol concentrations in patients with sleep disorders.

The potential of using hair cortisol to measure chronic stress in occupational healthcare; a scoping review

OBJECTIVES

Workplace-based selective prevention of mental health problems currently relies on subjective evaluation of stress complaints. Hair cortisol captures chronic stress responses and could be a promising biomarker for the early identification of mental health problems. The objective was to provide an overview of the state-of-the-art knowledge on the practical value of hair cortisol in the occupational setting.

METHODS

We performed a scoping review of cross-sectional and longitudinal studies in PubMed, Embase, and PsycINFO up to November 2019 assessing the relations of hair cortisol with work-related stressors, perceived stress, and mental health outcomes in healthy workers.

RESULTS

We found five longitudinal studies, of which two observed an increase in work-related stressors to be associated with higher hair cortisol, one found a relation with lower hair cortisol and one did not find a relationship. Findings of cross-sectional studies were also mixed. The one available longitudinal study regarding mental health showed that hair cortisol was not related to depressive symptoms.

CONCLUSIONS

Hair cortisol measurement within occupational health research is still in its early stage and more longitudinal studies are urgently needed to clarify its relationship with work-related stressors and perceived stress before hair cortisol can be used to identify workers at risk for mental health problems.

The hypothalamo-pituitary-adrenal axis and the autonomic nervous system in burnout

Burnout constitutes a serious health concern in the modern working environment. It is a stress-related condition that has developed as a result of a prolonged psychosocial stress exposure causing a persistent mismatch between demands and resources. The main symptom is emotional exhaustion, but physical fatigue, diminished professional efficacy, cynicism, and cognitive impairments are also associated with this condition. Burnout has been used both as a psychologic term in occupational settings and as a clinical diagnosis in patient populations, and there is currently no universally accepted definition and diagnostic criteria of burnout. It has been hypothesized that the two main stress response systems, the autonomic nervous system (ANS) and the hypothalamus-pituitary-adrenal axis (HPA axis), are involved in the pathogenesis of burnout. A common hypothesis is that in the early stages of chronic stress, the HPA axis and sympathetic ANS activity tend to be higher, while it will decrease with a longer duration of chronic stress to ultimately reach a state of hypoactivity in clinical burnout. The current research in this field shows many contradictory results. Thus there is no compelling evidence of either ANS or HPA dysfunction in burnout. However, there is partial support for the hypothesis of HPA and sympathetic hyperactivity in early stages, and HPA hyporeactivity and low vagal activity in more severe burnout cases, but high-quality studies investigating the causal links are still lacking.

Hair cortisol concentration as a biomarker of parental burnout

Parental Burnout (PB) is a chronic stress-related disorder experienced in the parental role. Recent studies have shown that PB is a serious condition with severe consequences for parents (e.g., suicidal ideations) and children (e.g., parental neglect and violence). However, PB's biological correlates have not yet been examined. Numerous studies suggest that hair cortisol concentration (HCC) is a valid biomarker of a variety of chronic stress conditions. HCC has been shown to be related to job burnout, but no studies have looked at the association between HCC and parental burnout. Given that the two forms of burnout are only weakly related, it is important to fill this gap. In this study, we compared HCC of parents suffering from PB (N = 119) to that of control parents (N = 59). We also examined the correlation between PB scores and HCC levels, controlling for job burnout symptoms. The results showed that HCC was 213 % higher in parents suffering from PB (mean level: 99.90 pg/mg) compared to controls (mean level: 46.83 pg/mg). Moreover, HCC was significantly related to PB (r = 0.27). These findings suggested that HCC can be considered as a biomarker of PB (though with caution, as 36.1 % of the parents in PB had HCC values equal to or below the mean of the control parents) and reinforce the view that HCC is a biomarker of chronic stress conditions. The HCC levels observed in parents suffering from PB point to the importance of this condition as well as its potential harmful consequences for their health.