Fatigue Sensitivity and Mental Health among Trauma-Exposed Firefighters

Abstract

Background:

Firefighters are faced with numerous work-related demands and stressors, including exposure to potentially traumatic events, and are thus at an increased risk for poor mental health outcomes. To better understand the mental health of trauma-exposed firefighters, the current study sought to examine the association of fatigue sensitivity with posttraumatic stress disorder (PTSD), anxiety, and depressive symptom severity in a cross-sectional study design.

Methods:

Participants included 107 (M_age = 40.8 years; SD_age = 8.95; age range: 21–67 years; 95.0% male) trauma-exposed firefighters.

Results:

Findings from the current study indicated that fatigue sensitivity was a statistically significant clinical correlate of PTSD, anxiety, and depressive symptom severity. The statistically significant incremental effects were small to medium across the mental health variables, but evident after accounting for years in the fire service, sleep quality, and trauma load.

Conclusions:

The present data provide initial empirical evidence for the role of fatigue sensitivity in terms of a broad range of mental health indices among trauma-exposed firefighters.

Introduction

Firefighters experience significant trauma exposure, with over 90% of firefighters reporting exposure to at least one traumatic event in their lifetime [1]. Indeed, firefighters are often faced with recurrent exposure to potentially traumatic events [e.g., medical emergencies; structural fires; 2] and higher occupational injury and fatality rates compared to other working populations [3, 4]. While the majority of firefighters are resilient despite recurrent trauma and stress exposure, exposure to traumatic events among firefighters is associated with various negative mental health outcomes among a significant subset of firefighters [e.g., posttraumatic stress disorder [PTSD], depression; 2, 5, 6]. Indeed, the mental health of firefighters has received increasing scientific and clinical attention in recent years [7]. Furthermore, firefighters are faced with numerous work-related demands that result in fatigue-related symptoms [8]. For example, fire departments commonly employ shift schedules [e.g., 24-hours on and 48-hours off; 9], which are associated with sleep disturbance and fatigue [10, 11]. Moreover, firefighters are often required to engage in strenuous physical activity contributing to acute physical stress and fatigue [12]. As such, it is important to consider individual difference factors in the context of fatigue in order to identify ‘at-risk’ firefighters who may be more likely to experience negative mental health outcomes.

One such construct that has received recent empirical attention is fatigue sensitivity. Fatigue sensitivity, assessed via the Fatigue Sensitivity Questionnaire [13], is defined as the fear of fatigue-related sensations (e.g., headaches) which arises from beliefs that such symptoms will lead to harmful personal consequences [e.g., something may be seriously wrong with me; 14]. To illustrate as it relates to the current context, a firefighter with elevated fatigue sensitivity may fear that fatigue-related symptoms (e.g., exhaustion) may lead to social judgement from others [e.g., my colleagues will think I am weak; 14]. Extant work among a variety of populations (e.g., college students, chronic pain populations) has found greater fatigue sensitivity is associated with poorer mental health, including elevated depression and anxiety symptoms [14, 15], even after accounting for fatigue severity or personality traits like neuroticism [16]. Drawing from this work, there is great utility in expanding this work to firefighters to determine the relevance of fatigue sensitivity to common mental health symptoms among this population with recurrent stress exposure [1] and risk for chronic fatigue [8]. Such work may aid in the clinical understanding and treatment of mental health symptoms among this vulnerable population.

Theoretically, fatigue sensitivity may be relevant to understanding adverse mental health problems among firefighters. For example, fatigue sensitivity amplifies emotional reactions to fatigue symptoms resulting in increased awareness to fatigue-related symptoms (e.g., low energy) and increased motivation to avoid fatigue-provoking stimuli [e.g., physical activity; 14, 17]. Trauma-exposed firefighters with elevated fatigue sensitivity may then experience concerns related to their ability to make important cognitive decisions when faced with fatigue-related symptoms (e.g., feeling drained). As such, trauma-exposed firefighters may become hypervigilant to such symptoms and engage in behaviors aimed to avoid such experiences (e.g., behavioral withdrawal), increasing risk for mental health symptoms, including greater PTSD, anxiety, and depressive symptom severity. Thus, improving our understanding of malleable cognitive-behavioral factors related to mental health among firefighters, such as fatigue sensitivity, has great potential to inform specialized evidence-based intervention programs.

The current study sought to test the association of fatigue sensitivity with PTSD, anxiety, and depressive symptom severity among trauma-exposed firefighters. It was expected that firefighters who endorsed greater levels of fatigue sensitivity would report greater PTSD, anxiety, and depressive symptom severity. We also expected the results to be evident even after accounting for variance by theoretically-relevant covariates of years in the fire service [18], sleep quality [19], and trauma load [i.e., number of trauma exposure event types experienced; 20].

Method

Participants

The present sample represents a subset of participants from a larger study examining stress, resilience, and well-being among firefighters. This sample is composed of 107 (M_age = 40.8 years; SD_age = 8.95; age range: 21–67 years; 95.0% male) career (full- and part-time) and volunteer firefighters, including those who also work as Emergency Medical Services (EMS) personnel as part of their firefighter duties. Firefighters were recruited from nine departments in and around a large metropolitan area in the southern United States (U.S.). Inclusion criteria for the larger study included being at least 18 years old and a current firefighter in career, volunteer, or combination (career and volunteer) fire departments. Exclusion criteria included an inability to provide voluntary, written consent. For the current analyses, only individuals that endorsed a PTSD Criterion A traumatic event (work related or non-work related) were included [21].

Approximately 23.0% of the sample identified their ethnicity as Hispanic/Latino. In addition, 75.0% of respondents identified their race as White, 6.0% identified as Black or African American, 6.0% identified as American Indian or Alaskan Native, 1.0% identified as Native Hawaiian or Pacific Islander, and 12.0% identified as ‘other.’ The average number of years in the fire service among this sample was 15.39 (SD = 8.43).

Descriptive and Covariate Measures

Demographic Questionnaire.

A demographic questionnaire was used to collect sociodemographic information (e.g., age, race, ethnicity, sex) and fire service history. In the current study, sociodemographic information was used to describe the sample and years in the fire service was included as a covariate.

Pittsburgh Sleep Quality Index [PSQI; 22].

The PSQI is a 19-item self-report measure assessing sleep quality and sleep disturbances over the past month. The PSQI generates 7 component scores measuring subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The PSQI has demonstrated good psychometric properties in past work [22]. For the current analyses, the one-item PSQI sleep quality subscale was used as a covariate with higher scores indicative of worse sleep quality.

Life Events Checklist for DSM-5 (LEC-5; Weathers eta l., 2013).

The LEC-5 is a self-report questionnaire used to screen for exposure to potentially traumatic events at any point during the lifespan [23]. Respondents are presented with 16 potentially traumatic events, (e.g., combat, sexual assault, transportation accidents) as well as an additional item labeled as ‘other,’ which assesses for potentially traumatic events that are not previously listed. Respondents are asked to indicate whether each event listed ‘happened to me,’ ‘witnessed it,’ ‘learned about it,’ ‘part of my job,’ or ‘not sure.’ Any event that was endorsed as ‘happened to me,’ ‘witnessed it,’ or ‘part of my job’ was coded as positive exposure to that particular traumatic event. Total number of trauma exposure types was summed to produce a total score (i.e. trauma load), which was used as a covariate in the current analyses.

Independent Variable Measure

Fatigue Sensitivity Questionnaire [FSQ; 14].

The FSQ is a 10-item self-report measure that assesses the tendency for individuals to interpret fatigue-related symptoms and sensations as having harmful physical, social, and/or cognitive consequences (e.g., “When I yawn in the presence of others, I fear what people might think of me”). Each item is assessed on a 4-point Likert-type scale ranging from 0 (Very Little) to 3 (Much/Very Much). The FSQ has demonstrated unidimensionality, excellent internal consistency, and strong convergent and discriminant validity in past work [14]. The total score was created by summing all items and was used as an independent variable in the current study and demonstrated good internal consistency (α = .91), consistent with past work [14].

Outcome Variable Measures

PTSD Checklist for DSM-5 [PCL-5; 24].

The PCL-5 is a 20-item self-report measure that examines PTSD symptom severity over the past month, according to the DSM-5 criteria [21]. Individuals were instructed to complete the PCL-5 with regard to the ‘worst’ traumatic event they endorsed on the LEC-5. Each item is rated on a 5-point Likert-type scale from 0 (not at all) to 4 (extremely). A PCL-5 total score was derived from summing all 20 items, and this was evaluated as a criterion variable in the current study. As in past work [25], the PCL-5 demonstrated excellent internal consistency (α = .96).

Overall Anxiety Severity and Impairment Scale [OASIS; 26].

The OASIS is a 5-item self-report measure of past-week anxiety symptom severity. Items are rated on a 5-point Likert-type scale ranging from 0 to 4. In the current study, the total score demonstrated excellent internal consistency (α = .91), consistent with past work [27]. The OASIS total score was evaluated as a criterion variable in the current study.

Overall Depression Severity and Impairment Scale [ODSIS; 28].

The ODSIS is a 5-item measure that assesses depressive symptom severity over the past week. Items are rated on a 5-point Likert-type scale ranging from 0 to 4. The total score demonstrated excellent internal consistency (α = .93), consistent with past work [28], and was examined as a criterion variable in the current study.

Procedure

Firefighters were recruited through nine career, volunteer, or combination fire departments within and surrounding a large metropolitan area in the southern U.S. Participants were recruited via department-wide email distribution lists in participating departments. The email notifications indicated that the purpose of the study is to better understand strength and resilience characteristics among firefighters, and how these characteristics may serve to influence overall well-being. They were also notified that they could choose to be entered for a chance to win one of several raffle prizes (e.g., assorted gift cards) for their participation. Once firefighters accessed the survey portal, they were provided with a description of the survey and the choice to review the online informed consent form. Firefighters were required to provide informed consent online before proceeding to the online self-report survey, administered via Qualtrics. This study protocol was approved by all participating departments and the relevant Institutional Review Board.

Analytic Strategy

Analyses were conducted using SPSS version 28. Sample descriptive statistics and bivariate correlations among study variables were examined. To evaluate the unique incremental validity of fatigue sensitivity regarding each criterion variable (i.e., PTSD, anxiety, and depressive symptom severity), three separate two-step linear regression analyses were conducted. For all analyses, step one included covariates of years in the fire service, sleep quality, and trauma load. Step two included fatigue sensitivity. Model fit for each of the steps was evaluated with the F statistic and an increase in variance was defined as a change in R². Change in R² and squared semi-partial correlations (sr²) were used as indices of effect size [interpreted as .01 = small, .09 = moderate, and .25 = large; 29]. The PTSD-relevant model was also examined after excluding the PCL-5 sleep disturbance item from the total score calculation.

Results

Descriptive Statistics and Bivariate Correlations

Descriptive statistics and bivariate correlations are presented in Table 1. In the current sample, 12% met criteria for probable PTSD diagnosis (i.e., a score ≥ 31 per the PCL-5), 10% met criteria for probable anxiety diagnosis (i.e., a score ≥ 8 per the OASIS), and 11% met criteria for probable depression diagnosis (i.e., a score ≥ 8 per the ODSIS). There was a statistically significant and positive correlation with fatigue sensitivity and PTSD, anxiety, and depressive symptom severity. In addition, there was a statistically significant and positive correlation with PTSD symptom severity and anxiety and depressive symptom severity. The anxiety symptom severity and depressive symptom severity correlation was also statistically significant and positive.

Table 1.

Bivariate Correlations and Descriptive Statistics among Study Variables.

Variable	1	2	3	4	5	6	7
1. Years in Service a	-	-	-	-	-	-	-
2. Sleep Quality a	.03	-	-	-	-	-	-
3. Trauma Load a	.13	−.10	-	-	-	-	-
4. Fatigue Sensitivity b	−.19	.10	−.05	-	-	-	-
5. PTSD Symptom Severity c	−.11	.31**	.18	.29**	-	-	-
6. Anxiety Symptom Severity c	−.02	.37***	.07	.39***	.62***	-	-
7. Depressive Symptom Severity c	−.08	.32**	.14	.33***	.63***	.71***	-
Mean	15.39	0.63	10.82	3.29	12.01	2.90	2.64
SD	8.43	1.07	2.29	4.97	14.71	3.61	3.54
Range	1–40	0–3	3–15	0–30	0–59	0–14	0–13

Note. N = 100.

^*p <.05

^**p < .01

^***p < .001.

^acovariate

^bindependent variable

^ccriterion variable

Regression Analyses

Regression results are presented in Table 2. With regard to PTSD symptom severity, step one of the model was statistically significant (R² = .16, F(3, 94) = 5.99, p <.001); sleep quality and trauma load emerged as statistically significant correlates. In step two, fatigue sensitivity was added to the model and the model remained statistically significant (R² = .19, F(4, 93) = 6.65, p <.001) and contributed to a statistically significant increase in variance (ΔR² = .07, F(1, 93)=7.40, p =.008); fatigue sensitivity, sleep quality, and trauma load were statistically significant correlates. Notably, this model was also conducted after excluding the PCL-5 sleep disturbance item (i.e., PCL-5 outcome variable total score calculation excluded the sleep disturbance item); the pattern and magnitude of effects remained consistent.

Table 2.

Hierarchical Linear Regression Results for PTSD Symptom Severity, Anxiety Symptom Severity, and Depressive Symptom Severity.

PTSD Symptom Severity
Step		b	SE	t	p	CI (l)	CI (u)	sr 2
1	Years of Service	−0.26	0.17	−1.53	.130	−0.61	0.08	.021
	Sleep Quality	4.60	1.30	3.54	<.001	2.02	7.19	.112
	Trauma Load	1.54	0.62	2.50	.014	0.32	2.77	.056
2	Years of Service	−0.18	0.17	−1.09	.281	−0.52	0.15	.010
	Sleep Quality	4.24	1.27	3.35	.001	1.73	6.76	.094
	Trauma Load	1.58	0.60	2.65	.010	0.39	2.77	.059
	Fatigue Sensitivity	0.75	0.28	2.72	.008	0.20	1.30	.062
Anxiety Symptom Severity
Step		b	SE	t	p	CI (l)	CI (u)	sr 2
1	Years of Service	−0.01	0.04	−0.27	.785	−0.10	0.07	.001
	Sleep Quality	1.29	0.32	4.02	<.001	0.65	1.92	.145
	Trauma Load	0.17	0.15	1.14	.258	−0.13	0.47	.012
2	Years of Service	0.02	0.04	0.45	.654	−0.06	0.10	.002
	Sleep Quality	1.16	0.30	3.88	<.001	0.56	1.75	.115
	Trauma Load	0.18	0.14	1.30	.196	−0.10	0.46	.013
	Fatigue Sensitivity	0.27	0.07	4.11	<.001	0.14	0.40	.130
Depressive Symptom Severity
Step		b	SE	t	p	CI (l)	CI (u)	sr 2
1	Years of Service	−0.04	0.04	−1.03	.305	−0.13	0.04	.010
	Sleep Quality	1.12	0.32	3.55	<.001	0.49	1.75	.114
	Trauma Load	0.29	0.15	1.96	.053	−0.01	0.59	.035
2	Years of Service	−0.02	0.04	−0.49	.625	−0.10	0.06	.002
	Sleep Quality	1.02	0.30	3.35	.001	0.41	1.62	.092
	Trauma Load	0.30	0.14	2.11	.038	0.02	0.58	.036
	Fatigue Sensitivity	0.21	0.07	3.19	.002	0.08	0.34	.076

Note. N for analyses is 100.

In terms of anxiety symptom severity, step one was statistically significant (R² = .15, F(3, 95) = 5.57, p < .001); sleep quality emerged as a statistically significant correlate. In step two, the model with fatigue sensitivity remained significant (R² = .28, F(4, 94) = 9.11, p <.001) and accounted for a statistically significant increase in variance (ΔR² = .13, F(1, 94)=16.93, p < .001). Fatigue sensitivity and sleep quality were statistically significant correlates of anxiety symptom severity.

In regard to depressive symptom severity, step one was statistically significant (R² = .14, F(3, 95) = 5.20, p = .002); sleep quality emerged as a statistically significant correlate. In step two, with the addition of fatigue sensitivity, the model remained significant (R² = .23, F(4, 94) = 6.81, p <.001) and contributed to a statistically significant increase in variance (ΔR² = .08, F(1, 94)=10.14, p = .002); fatigue sensitivity, sleep quality, and trauma load were statistically significant correlates.

Discussion

The current study sought to examine the incremental association of fatigue sensitivity and mental health among a sample of trauma-exposed firefighters. Results indicated that fatigue sensitivity was associated with greater PTSD, anxiety, and depressive symptom severity. Findings were evident even after accounting for theoretically-relevant covariates of years in the first service, sleep quality, and trauma load. Of note, the observed fatigue sensitivity effects were small (6% and 8% for PTSD and anxiety symptom severity, respectively) to medium (13% for depressive symptom severity). Results are in line with previous work among other samples [14–16] indicating fatigue sensitivity negatively impacts mental health and extends this work to a sample of trauma-exposed firefighters.

Fatigue sensitivity may operate through individual difference factors to contribute to greater PTSD, anxiety, and depressive symptom severity. For example, individuals with elevated fatigue sensitivity may be more apt to engage in experiential avoidance of fatigue-provoking stimuli (e.g., social activities, exercise) in an effort to downregulate distress or concerns associated with such symptoms [e.g., “When I feel sluggish, I am afraid that people will judge me negatively”; 14]. Experiential avoidance, in turn, has been found to be associated with greater subjective distress and coping difficulties [30], increasing risk for mental health severity. Moreover, a specific experiential avoidance tactic frequently evidenced by this population in an effort to self-medicate, is alcohol use [31–34]. Indeed, alcohol use is a significant public health concern within firefighter populations [5, 35–39] and such behavior is associated with elevated mental health symptoms [37, 38, 40–46]. Thus, if the proposed relations are validated longitudinally, efforts to decrease fatigue sensitivity may aid in improvement of coping oriented behaviors (e.g., alcohol use) and mental health outcomes among this underserved population.

Given the high-rates of fatigue among firefighters [8] and risk for negative mental health among trauma-exposed firefighters [e.g., PTSD, depression; 2, 5, 6], providing psychoeducation on fatigue sensitivity to trauma-exposed firefighters may be clinically relevant in the context of PTSD, anxiety, and depressive symptoms. Extant work has suggested that firefighters report fatigue as a “taboo” topic and therefore may be particularly concerned with the social consequences of reporting such symptoms [47]. Such behavior may increase risk for hypervigilance and fears related to fatigue-related symptoms and thus negatively impact mental health (e.g., increase PTSD, anxiety, or depression symptoms). As such, tactics aimed to normalize fatigue-related symptoms and reduce fears related to the potential consequences of fatigue may promote less hypervigilance to such internal sensations and promote more adaptive behavioral responses. Specifically, trauma-exposed firefighters may be less likely to withdraw or avoid activities which may contribute to a positive impact on symptom severity as related to PTSD, anxiety, and depression.

There are a number of limitations worth noting. First, the relations of variables were examined in a cross-sectional design. Future longitudinal studies are needed to better understand the interplay between the studied variables. Second, all measures utilized in the current study were collected via self-report. Thus, some of the observed relations may be due, in part, to shared method variance. Future studies might incorporate interview-based measures of symptoms and objective sleep measures (e.g., actigraphy) to develop a more fine-grained understanding of these associations. Finally, the current sample consisted of a rather homogenous sample of active firefighters (i.e., 95% male and 75% white). Thus, future studies would benefit from oversampling female and ethnically/racially diverse participants. Moreover, future studies would also benefit from examining the proposed relations among retired firefighters [48].

Overall the current study provides initial support for the role of fatigue sensitivity in terms of mental health, including PTSD, anxiety, and depressive symptom severity among trauma-exposed firefighters. There may be utility in assessing and addressing fatigue sensitivity within fire departments to offset the mental health burden among this subgroup of the population.