Posttraumatic stress disorder (PTSD) is a debilitating and common consequence of military service. PTSD is associated with increased incidence of mood disturbances (e.g., anxiety). Additionally, veterans with PTSD often have poor-quality sleep and poor emotion regulation ability. We sought to assess whether such sleep and emotion regulation deficits contribute to mood disturbances. In 144 veterans, using a double moderation model, we tested the relationship between PTSD and anxiety and examined whether sleep quality and emotion regulation interact to moderate this relationship. We found that PTSD predicts higher anxiety in veterans with poor and average sleep quality who utilize maladaptive emotion regulation strategies. However, there was no relationship between PTSD and anxiety in individuals with good sleep quality, regardless of emotion regulation. Similarly, there was no relationship between PTSD and anxiety in individuals with better emotion regulation, regardless of sleep quality. Results were unchanged when controlling for history of traumatic brain injury (TBI), despite the fact that those with both PTSD and TBI had the poorest emotion regulation overall. Taken together, these results suggest that good-quality sleep may be protective against poor emotion regulation in veterans with PTSD. Sleep may therefore be a target for therapeutic intervention in veterans with PTSD and heightened anxiety.
Posttraumatic stress disorder (PTSD), which can occur after a traumatic event, is characterized by negative alterations in cognition, mood, and arousal/reactivity [
Given the prevailing physiological hyperarousal present in PTSD, it is perhaps not surprising that sleep issues are common in this population. In fact, insomnia is the most commonly reported symptom of PTSD [
Individuals with PTSD also suffer from impaired emotion regulation, which involves the voluntary or involuntary process of modulating one’s own emotional experience [
Importantly, the type of strategy used for emotion regulation seems to be moderated by sleep quality. Vantieghem and colleagues recently showed that individuals with sleep issues (i.e., insomnia) suppress emotions more frequently and are less likely to use cognitive reappraisal than those without insomnia [
The current study therefore is aimed at examining the potential relationship between sleep quality and emotion regulation in veterans with and without PTSD. We specifically focus on a core feature of PTSD, that is, anxiety symptomatology, and examine how sleep quality and emotion regulation interact to moderate this relationship. Using a cohort of veterans with and without PTSD, we hypothesized the following: (1) Individuals with PTSD would have higher anxiety than veterans without PTSD. (2) Individuals with PTSD would have poorer sleep quality than veterans without PTSD. (3) Individuals with PTSD would utilize higher levels of expressive suppression and lower levels of cognitive reappraisal than veterans without PTSD. (4) Sleep quality and emotion regulation strategy use would interact to moderate the link between PTSD and anxiety. Furthermore, given that PTSD is often comorbid with TBI in the veteran population, we also examined the effects of TBI on these hypotheses as a contributing factor.
In total, 144 veterans from the Veterans Affairs (VA) Portland Healthcare System participated under a VA IRB approved protocol (MIRB number 3641, PI: Lim). Twenty-four individuals met criteria for PTSD on the basis of self-reported symptoms (cluster criteria in the PTSD Checklist 5 or PCL-5, total score > 33 [
The main analyses were conducted using several self-reported questionnaires: (1) Emotion Regulation Questionnaire (ERQ) [
The ERQ is a 10-item scale that measures an individual’s tendency to use specific emotion regulation strategies [
The NIH PROMIS battery is a multidomain test with a range of outcomes pertaining to physical, mental, and social wellbeing. Participants were asked to rate to what extent four items about anxiety symptoms described them (e.g., “In the past 7 days, my worries overwhelmed me.”). Items are 5-point Likert scales: 5 = “never”, 4 = “rarely”, 3 = “sometimes”, 2 = “often”, and 1 = “always”. A lower number indicates higher dysfunction.
The ISI is a 7-item measure assessing insomnia severity (i.e., difficulty initiating and staying asleep). Individual items are 5-point Likert scales: 0 = “none”, 1 = “mild”, 2 = “moderate”, 3 = “severe”, and 4 = “very severe”. A higher score indicates higher dysfunction.
The FOSQ-10 is a 10-item measure assessing whether an individual has poor quality of life due to poor sleep quality. Individual items are 4-point Likert scales: 1 = “yes, extreme difficulty”, 2 = “yes, moderate difficulty”, 3 = “yes, a little difficulty”, and 4 = “no difficulty”; however, half of the items are a 5-point Likert scale that includes a rating of 0 = “I do not do this activity for other reasons”. The survey has 5 subscales: (1) activity level, (2) vigilance, (3) intimacy and sexual relationships, (4) general productivity, and (5) social outcomes. A lower score indicates higher dysfunction.
The PHQ-9 is a 10-item measure assessing the presence of depressive symptoms. Individual items, which enquire about how frequently participants experience the presented symptoms, are a 4-point Likert scale: 0 = “not at all”, 1 = “several days”, 2 = “more than half the days”, and 3 = “nearly every day.” A higher score indicates higher dysfunction.
Individuals met criteria for PTSD on the basis of symptoms reported in the Posttraumatic Stress Disorder Checklist (PCL-5) [
Two trained researchers reviewed medical records from the Portland VA electronic medical record system to determine whether veterans had a history of TBI. Individuals with self-reported TBI that was not confirmed in the medical record were excluded from the sample.
Consecutive veterans who entered the Portland VA Sleep Clinic for a clinical diagnostic sleep study were recruited to participate as part of a larger study (MIRB number 3641, factors that affect adherence to treatment for sleep apnea, PI: Lim). All participants were in the lab for overnight sleep assessments and were asked by a trained research coordinator whether they would like to participate. Veterans who wished to participate completed all questionnaires either in person, via mail, or by phone, between the time of consent and 12 months later.
IBM SPSS Statistics 23 (Armonk, NY) was used to conduct statistical analyses. Analyses were conducted in several phases. First, descriptive statistical tests were conducted to determine whether groups differed at cross section in meaningful ways. One-way ANOVA tests were used to determine whether groups differed for demographic factors (e.g., age), objective sleep characteristics (e.g., TST and sleep staging), and self-reported functioning (e.g., via the FOSQ-10 and PHQ-9). If a significant difference between groups was detected, post hoc Tukey tests were used to determine which groups differed.
Next, 2 × 2 ANOVA tests (TBI versus non-TBI, PTSD versus non-PTSD) were used to assess whether groups differed for the outcome measures of interest. For this set of analyses, a 2 × 2 ANOVA was utilized rather than a one-way ANOVA so that we could examine whether PTSD and TBI interacted to synergistically affect outcomes of interest. Outcome measures were cognitive reappraisal (higher = more use of that strategy), expressive suppression (higher = more use of that strategy), ISI scores (sleep quality; higher = more sleep problems), and NIH PROMIS anxiety scores (anxiety; lower = more anxiety). In addition, an emotion regulation ratio was calculated, which consists of cognitive reappraisal divided by expressive suppression (higher = more cognitive reappraisal use, lower = more expressive suppression use), so both strategies could be assessed in one continuous outcome measure.
Lastly, given our a priori hypotheses about sleep quality interacting with emotion regulation to affect anxiety symptomatology in individuals with PTSD, moderation analyses were conducted to determine whether sleep (ISI scores) and emotion regulation (emotion regulation ratio) both moderate the relationship between PTSD (yes/no diagnosis) and anxiety (NIH PROMIS scores) (see Figure
Conceptual model of the relationship between PTSD status, sleep quality, emotion regulation strategy use, and anxiety symptoms.
Moderation analyses, discussed directly above, were conducted using the SPSS PROCESS macro (Model 3). PROCESS calculates statistical significance using 95% confidence intervals to determine the effect of the predictor on the outcome measure. PROCESS also calculates the interaction effects of the moderators by testing the predictive effect of each factor at different levels (e.g., a low emotion regulation ratio and good sleep quality or a high emotion regulation ratio with poor sleep quality). Each predictor level was determined by values plus or minus 1 standard deviation from the centered mean. In order to eliminate both statistical power limitations and concerns about statistical assumption violations, 5000 bootstrap iterations were used within the macro (at least 2000 bootstrap iterations are recommended [
Given the potential bias in our sample, which was referred for evaluation of sleep disorders, polysomnography- (PSG-) derived measures of sleep were assessed for group differences using ANOVA tests and results are reported below.
Demographic information is listed in Table
Demographics (mean ± standard deviation). BMI = body mass image; PHQ-9 = Patient Health Questionnaire version 9; FOSQ-10 = Functional Outcomes of Sleep Questionnaire version 10; NIH PROMIS = National Institutes of Health Patient-Reported Outcomes Measurement Information System anxiety items; TST = total sleep time; SE = sleep efficiency; NREM1 (%) = percent of the night in non-REM sleep stage 1; NREM2 (%) = percent of the night in non-REM sleep stage 2; SWS (%) = percent of the night in slow wave sleep; REM (%) = percent of the night in rapid eye movement sleep; AHI = apnea/hypopnea index.
Controls | TBI only | PTSD only | PTSD + TBI | |||
---|---|---|---|---|---|---|
Age | 59.1 ± 13.3 | 56.2 ± 15.3 | 55.7 ± 13.5 | 48.8 ± 21.3 | 1.6 | 0.13 |
BMI | 33.0 ± 6.8 | 33.0 ± 7.5 | 32.2 ± 5.4 | 29.3 ± 5.0 | 1.0 | 0.42 |
Gender (% male) | 89.4 | 90 | 80.1 | 100 | 2.7 | 0.45 |
NIH PROMIS | 16.0 ± 3.1 | 14.4 ± 4.3 | 13.0 ± 3.6 | 10.9 ± 4.0 | 10.6 | <0.001 |
PHQ-9 | 6.6 ± 4.8 | 8.7 ± 4.7 | 13.3 ± 5.6 | 14.0 ± 7.1 | 15.0 | <0.001 |
FOSQ-10 | 15.9 ± 3.1 | 14.9 ± 3.7 | 10.9 ± 3.0 | 12.3 ± 4.3 | 15.6 | <0.001 |
ISI | 12.0 ± 6.1 | 13.7 ± 5.04 | 17.2 ± 5.9 | 18.5 ± 5.4 | 6.8 | <0.001 |
TST (min) | 294.3 ± 101.1 | 313.4 ± 67.9 | 311.2 ± 89.0 | 286.4 ± 113.5 | 0.4 | 0.76 |
SE (%) | 69.0 ± 18.7 | 72.9 ± 13.9 | 71.5 ± 18.6 | 65.4 ± 22.7 | 0.5 | 0.69 |
NREM1 (%) | 12.1 ± 5.7 | 12.7 ± 4.9 | 11.6 ± 5.4 | 10.1 ± 3.8 | 0.6 | 0.65 |
NREM2 (%) | 42.5 ± 15.7 | 46.1 ± 15.3 | 46.2 ± 13.7 | 38.7 ± 20.3 | 0.8 | 0.49 |
SWS (%) | 1.7 ± 4.2 | 1.2 ± 3.1 | 1.3 ± 3.8 | 1.5 ± 2.5 | 0.1 | 0.94 |
REM (%) | 11.7 ± 7.4 | 11.8 ± 6.9 | 11.0 ± 5.7 | 13.7 ± 9.5 | 0.3 | 0.81 |
AHI | 19.5 ± 20.0 | 13.7 ± 11.1 | 16.5 ± 11.7 | 18.5 ± 15.5 | 0.7 | 0.57 |
There were several mental health/quality-of-life questionnaires for which groups differed. For example, there was a significant difference between groups for the NIH PROMIS anxiety items (Figure
Groups differ on sleep and mental health based on TBI and PTSD status. Asterisk indicates that a given group differed significantly from veteran controls. (a) National Institutes of Health Patient-Reported Outcomes Measurement Information System (NIH PROMIS) anxiety items; (b) Insomnia Severity Index (ISI) scores; (c) Patient Health Questionnaire version 9 (PHQ-9) scores; (d) Functional Outcomes of Sleep Questionnaire version 10 (FOSQ-10) scores.
Next, as hypothesized, groups differed significantly on the ISI (Figure
Groups also differed significantly on the PHQ-9 questionnaire (Figure
Lastly, groups differed significantly on the FOSQ-10 (Figure
We next conducted 2 × 2 ANOVA tests to determine whether emotion regulation strategies differed between groups. Contrary to hypotheses, when using cognitive reappraisal as an outcome measure, there was no main effect of PTSD, a trending main effect of TBI (
PTSD and TBI interact to predict certain outcomes. Black lines = PTSD; gray lines = no PTSD. (a) Usage of cognitive reappraisal (higher = more use of that strategy); (b) usage of expressive suppression (higher = more use of that strategy); (c) the ER ratio comprising both emotion regulation strategies (higher indicates more use of cognitive reappraisal, less use of expressive suppression).
We next conducted moderation analyses to determine the conditional effect of PTSD on anxiety symptomatology at different levels of the moderators (sleep and emotion regulation). In the omnibus model, as expected, having PTSD was a significant predictor of higher anxiety symptomatology (
Table
PTSD presence predicts higher anxiety symptoms at each level of the moderators. Bold indicates statistical significance.
Emotion regulation strategy | Sleep quality | Beta | SE of beta | Lower CI | Upper CI | ||
---|---|---|---|---|---|---|---|
Suppression | Good | −2.26 | 1.56 | −1.44 | 0.15 | −5.36 | 0.83 |
Suppression | |||||||
Suppression | |||||||
Equal utilization | Good | −1.77 | 1.40 | −1.26 | 0.20 | −4.55 | 1.00 |
Equal utilization | |||||||
Equal utilization | |||||||
Reappraisal | Good | −1.28 | 1.47 | −0.87 | 0.38 | −4.19 | 1.62 |
Reappraisal | Average | −1.33 | 0.97 | −1.37 | 0.17 | −3.26 | 0.58 |
Reappraisal | Poor | −1.39 | 0.95 | −1.45 | 0.14 | −3.27 | 0.49 |
We conducted the same set of analyses while including TBI status as a covariate. Contrary to predictions, results were nearly identical to those noted above, indicating that the conditional effect of PTSD on anxiety symptomatology is not impacted by history of TBI.
Our results demonstrate the strong and complex links between PTSD, anxiety, sleep quality, and emotion regulation. As expected, we found that individuals with PTSD reported more anxiety and poorer subjective sleep compared to control subjects. With regard to emotion regulation, individuals with PTSD used emotion suppression (maladaptive) more so than cognitive reappraisal (adaptive) compared to control subjects. Individuals with PTSD + TBI showed the lowest emotion regulation scores (most maladaptive) across groups.
In particular, we found that the diagnosis of PTSD predicted higher anxiety in individuals who both (1) utilize expressive suppression to a greater extent than cognitive reappraisal or utilize expressive suppression and cognitive reappraisal equally and (2) report less than good sleep quality. Thus, although anxiety was significantly correlated with poor sleep quality, there was also an interaction between sleep quality and emotion regulation strategy use. The interaction suggests that PTSD predicts anxiety symptoms
Our findings are consistent with the results of a recent longitudinal study that examined the relationship between sleep, emotion regulation, and depression. Poor emotion regulation was found to mediate the relationship between poor sleep at baseline and depression at 6-month follow-up. The authors suggested that sleep was a causal factor in influencing emotion regulation and depression. Although our model examines anxiety and not depression, we believe that these models are not mutually exclusive, as depression and anxiety are highly comorbid [
It is important to note that opposite causality (or bidirectional causality) is possible, as better emotion regulation could be protective against poor sleep quality. Individuals utilizing poor emotion regulation skills may have maladaptive thought processes that could disturb sleep. For instance, higher use of expressive suppression has been linked with higher levels of rumination [
In this study, we also aimed to assess the potentially moderating effect of traumatic brain injury (TBI) on sleep and emotion regulation. Although it is difficult to estimate cooccurrence of PTSD and TBI, a large cohort study found that one-third of veterans who had a TBI also have comorbid PTSD symptoms [
Many of the symptoms experienced during the chronic phase of recovery following TBI are similar in clinical presentation to PTSD symptoms. Specifically, anxiety, depression, irritability, and anger have been associated with both diagnoses [
However, unexpectedly, inclusion of TBI in our moderation model did not impact the outcomes of interest. In other words, the relationship between PTSD and anxiety symptomatology (and conditional the effects at each level of the moderators) was not affected by TBI history. It is possible that the effect of PTSD is “overriding” that of TBI, which is consistent with previous literature on these topics. Vanderploeg and colleagues tested a model several years ago to determine whether PTSD and TBI independently or concurrently predicted tested outcomes (e.g., cognitive and emotional symptoms) [
Sleep disturbances are often thought of as a hallmark feature in individuals with PTSD. However, the impact of these sleep issues on quality of life—and the possible interrelationships between sleep and other factors—remains relatively unexplored. Our findings that sleep and emotion regulation interact to moderate the relationship between PTSD and anxiety symptoms could have meaningful implications for understanding barriers to treatment in veterans with PTSD.
For example, previous work has shown that improving poor-quality sleep improves PTSD severity. Treating sleep disorders (e.g., insomnia and OSA) lowers PTSD symptoms, such as nightmare frequency, unwanted thoughts, and distress [
Individuals with PTSD are 10 times more likely to have generalized anxiety disorder than those without PTSD [
The results of this study must be interpreted in the context of the study limitations. Our cohort was recruited from a single site from a single clinic, the Portland VA Sleep Clinic. By definition, these subjects are referred for evaluation of sleep complaints, which presents potential sample bias in our results. Thus, the sleep characteristics of our sample (and related factors) may not be generalizable to the population at large.
Similarly, our sample was predominantly male, as is generally representative of the veteran population. Because most veterans are male, we believe that our results have external validity and some generalizability to other veteran populations. However, due to this bias, we were unable to assess sex as a biological variable. Given that females tend to have more military-related mental health issues than males [
Lastly, this study utilized a cross sectional design, limiting causal and directional interpretability. Although we surmise, based on previous literature, that sleep is causally impacting emotion regulation, it is possible that emotion regulation is impacting sleep. Poor emotion regulation itself may lead to mental health issues [
Given our results, there are two clear foreseeable steps that could be taken to follow up on this work. First, a longitudinal study should be conducted to determine whether sleep issues precede emotion regulation issues or vice versa. There is ample evidence to support the idea that poor sleep worsens emotional functioning, and in particular, there is evidence that poor sleep precedes the development of PTSD (but notably, PTSD does not precede the development of sleep disturbances) [
After directionality is established, interventions could be implemented and assessed for efficacy. As discussed, there are many treatments for sleep disruption in individuals with PTSD, such as cognitive behavioral therapy for insomnia, image rehearsal therapy for nightmares, and medications [
We found a relationship between PTSD and anxiety in veterans with poor/average sleep quality who utilize maladaptive emotion regulation strategies (i.e., utilizing expressive suppression more than cognitive reappraisal or using both strategies equally). However, in veterans who sleep well, there was no relationship between PTSD and anxiety, even when emotion regulation was poor. We posit that good-quality sleep is protective against poor emotion regulation in veterans with PTSD. Improving sleep could, in effect, improve anxiety symptomatology in this population. Future experimental work should implement sleep intervention techniques (e.g., cognitive behavioral therapy) in veterans in order to enhance wellbeing and quality of life in this group.
The final, complete dataset will be available to interested users under a VA-approved data-sharing agreement that provides for: (1) a commitment to using the data only for research purposes and not to identify any individual participant; (2) a commitment to securing the data using appropriate computer technology; and (3) a commitment to destroying or returning the data after analyses are completed. Because there remains the possibility of deductive disclosure of subjects with unusual characteristics, data disclosure will be considered on a case-by-case basis; interested users may contact the corresponding author directly to initiate this process.
The contents do not represent the views of the U.S. Department of Veterans Affairs or the United States Government. Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting true views of the Department of the Army or the Department of Defense. The investigators have adhered to the policies for protection of human subjects as prescribed in AR 70–25.
The authors declare that there is no conflict of interest regarding the publication of this paper.
The authors would like to express their sincere appreciation and gratitude for the participation of all subjects, to the staff at the VA Portland Health Care System Sleep Disorders Clinic. Specific acknowledgements go to Ryan A. Opel for assistance with data curation and Alexander Q. Chau and Matthew R. Gieger for assistance with chart review. This work was supported by the Sleep Research Society Mentor-Mentee Program award, awarded to Janna Mantua. This work was also supported with resources and the use of facilities at the VA Portland Health Care System, VA Career Development Award no. IK2 BX002712, NIH EXITO Institutional Core, no. UL1GM118964, the Portland VA Research Foundation to Miranda M. Lim, and VA OAA Post-doctoral Nursing Research Fellowship to Kris B. Weymann.