Behavioral Sleep Medicine, 13:255–264, 2015 Copyright © Taylor & Francis Group, LLC ISSN: 1540-2002 print/1540-2010 online DOI: 10.1080/15402002.2014.880344
Sleep Diaries of Vietnam War Veterans With Chronic PTSD: The Relationships Among Insomnia Symptoms, Psychosocial Stress, and Nightmares Philip R. Gehrman Philadelphia Veterans Affairs Medical Center; Department of Psychiatry University of Pennsylvania
Gerlinde C. Harb Philadelphia Veterans Affairs Medical Center
Joan M. Cook Yale University; National Center for PTSD, Boston
Holly Barilla University of Pennsylvania
Richard J. Ross Philadelphia Veterans Affairs Center; Department of Psychiatry University of Pennsylvania Impaired sleep and nightmares are known symptoms of posttraumatic stress disorder (PTSD) in the veteran population. In order to assess prospectively the sleep disturbances in this population, sleep diaries are an effective way to obtain information over an extended period of time. In this investigation, a sample of veterans (N D 105) completed daily sleep diaries for a 6-week period. Greater PTSD severity and nightmare-related distress were correlated with more awakenings, shorter duration of sleep, longer sleep latency, and greater frequency of nightmares. Perceived frequency of daytime stressors was associated with an increased number of nightmares, nightmarerelated distress, and longer sleep latency. The use of sleep diaries in future investigations may allow targeted treatments for veteran populations with PTSD and sleep disturbances. Correspondence should be addressed to Philip Gehrman, PhD, Department of Psychiatry, University of Pennsylvania, 3535 Market Street, Suite 670, Philadelphia, PA 19104. E-mail: [email protected]
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Understanding and treating the sleep disturbances related to posttraumatic stress disorder (PTSD) has recently received increased attention (Nappi et al., 2012). Two of the most common symptoms of PTSD are recurrent nightmares and insomnia (Neylan et al., 1998). These forms of sleep disturbance cause significant distress and impairment in daytime functioning (Levin & Nielsen, 2007; Neylan et al., 1998; Zadra & Donderi, 2000), and are very often difficult to treat (Belleville, Guay, & Marchand, 2011; Galovski, Monson, Bruce, & Resick, 2009; Zayfert & DeViva, 2004). Sleep disturbance seems to be particularly common in PTSD related to military trauma (Neylan et al., 1998). Research on the sleep disturbances in PTSD has relied almost entirely on retrospective assessments of sleep using standardized self-report questionnaires. Retrospective assessments can be strongly influenced by a number of self-report biases, such as the tendency to be overly influenced by atypical events (Stone & Shiffman, 2002). Prospective assessment of sleep characteristics can reduce the impact of self-report biases and yield more accurate information. For example, Lancee and colleagues (2008) found significant differences in nightmare frequency between retrospective questionnaires and prospective daily logs. In this sample of college students, the use of retrospective questionnaires led to systematic underreporting of nightmare frequency. Prospective assessment of sleep characteristics is routinely accomplished using daily sleep diaries, for which respondents are instructed to answer a series of questions pertaining to sleep/wake the preceding night shortly after awakening. Although sleep and nightmare diaries are routinely utilized in clinical trials of sleep-focused treatments in PTSD populations, rarely are these data reported on or investigated in detail. A particular value of prospective assessment using sleep diaries is the opportunity to examine temporal relationships among variables that can be measured on a regular basis. Although veterans with PTSD experience poor sleep overall, there is likely night-to-night variability in severity as has been documented in individuals with primary insomnia (Perlis et al., 2010). One potential source of variability is participants’ daytime experiences. Self-reported stress levels are known to correlate with sleep disturbance across individuals (Healey et al., 1981). It would be reasonable to suspect that, within an individual, days with higher levels of stress would be followed by worse sleep and more nightmares the following night. Prospective assessment of sleep and stress levels would permit this and other, related questions to be examined. The goal of this investigation was to conduct analyses of sleep diary data collected as part of a clinical trial of psychological sleep-focused treatment in a sample of veterans with PTSD. The data were examined with regard to patterns of sleep and nightmares overall and within days. It was hypothesized that greater severity of PTSD would be associated with poorer sleep, and that days with higher frequency of daily stressors would be associated with worse sleep at night.
METHODS Participants The data for these analyses are taken from a larger randomized, controlled trial of two psychological therapies for Vietnam War veterans with severe, chronic PTSD (Cook et al., 2010). For that trial, 156 male Vietnam War veterans receiving mental health services at the Philadelphia Veterans Affairs (VA) Medical Center were screened for eligibility; inclusion
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TABLE 1 Participants’ Baseline Sociodemographics and Clinical Characteristics
Age (Mean [SD]) Ethnicity Caucasian African American Other Education Did not complete high school Graduated from high school Completed some college Employment Full or part-time Retired Unemployed Combat Exposure Scale (Mean [SD]) Note.
Imagery Rehearsal n D 61
Sleep and Nightmare Management n D 63
59.79 (3.18)
59.06 (3.86)
27 (44.3) 30 (49.2) 4 (6.6)
25 (39.7) 34 (54.0) 4 (6.4)
10 (16.4) 23 (37.7) 28 (45.9)
9 (14.3) 26 (41.3) 17 (44.5)
6 (9.8) 34 (55.7) 21 (34.4) 29.27 (9.23)
16 (26.2) 29 (47.5) 16 (26.2) 29.31 (7.79)
Differences t(122) D 1.14 2 .2; N D 124/ D 0:3
2 .3; N D 124/ D 1:51
2 .3; N D 122/ D 6:0
t.88/ D 1:14; p D 0:26
All cells show n and percentage, unless otherwise noted. *p < .05; **p < .01.
criteria were: male gender, diagnosis of current PTSD due to combat in Vietnam as assessed with the Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995), currently experiencing combat-related nightmares at least once a week for greater than six months, and clinically significant sleep disturbance as indicated by a global score of five or more on the Pittsburgh Sleep Quality Index (PSQI; Buysse, Reynolds, Monk, Berman, & Kupfer, 1989). Comorbid major depression and/or an anxiety disorder other than PTSD were allowed. Individuals taking psychoactive medications were required to be on a stable regimen for a minimum of three months before they were eligible to participate. Exclusion criteria were: schizophrenia and other psychotic disorders, bipolar disorder, active substance abuse or dependence in the past six months, and medical disorders known to impact sleep (e.g., narcolepsy). Participants for whom there was a high suspicion of undiagnosed sleep apnea based on the Multivariable Apnea Predictor (MAP; Maislin et al., 1995) were also excluded. Of the 156 men evaluated for eligibility, 18 did not meet study criteria, 4 elected not to participate after evaluation but prior to consenting, and 10 withdrew before being assigned to a treatment condition. The final sample consisted of 124 veterans who were randomized to receive either one of two cognitive-behavioral therapies, Imagery Rehearsal (n D 61) or Sleep and Nightmare Management (n D 63). The study did not find significant improvements in nightmares as a result of these treatments, although both produced improvements in sleep quality and PTSD severity. Demographic information describing the sample is provided in Table 1. Procedure Participants were recruited for the IRB-approved clinical trial with the assistance of mental health clinic providers and flyers posted in waiting room areas. After giving written informed
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consent, veterans completed a self-report battery at baseline and had an interview with a clinical psychologist, who administered the SCID-IV-P and the CAPS to confirm a diagnosis of PTSD. When a sufficient number of veterans (6 to 10) were recruited to form two therapy groups (one for Sleep and Nightmare Management and one for Imagery Rehearsal), participants were randomly assigned to one of the treatment conditions. Both treatments were delivered according to manualized protocols. Treatment was conducted in group format, in six weekly 90-min sessions. Medication use was tracked throughout treatment. Measures The PSQI is a widely used 19-item self-report measure of sleep quality and sleep disturbances during the past month. The items generate seven component scores, each ranging from 0 to 3. The sum of the scores for the seven components yields one global score, which ranges from 0 to 21, with higher scores indicating worse sleep quality. The Nightmare Effects Survey (NES) is an 11-item measure used to assess psychosocial impairment attributed to nightmares, rated on a 5-point scale (Krakow et al., 2000). Scores range from 0 to 44, with higher scores indicating greater impairment and distress due to nightmares. The PTSD Checklist-Military (PCL-M) is a 17-item measure of PTSD symptoms based on DSM-IV criteria for PTSD (Weathers, Litz, Herman, Huska, & Keane, 1993). Using a 5-point Likert scale, subjects indicate the extent to which they have experienced each symptom in the past month. Scores range from 17 to 75, with higher scores indicating more severe PTSD. The Beck Depression Inventory (BDI) is a measure of cognitive, affective, and somatic symptoms of depression (Beck & Steer, 1987). The BDI is a 21-item self-report measure in which individuals choose the statement that best describes the way they have been feeling during the past week. Scores range from 0 to 63, with higher scores indicating more severe depression. Throughout treatment, participants completed daily sleep diaries that were divided into two parts. The first page was completed at night before going to bed; it asked about napping during the day, consumption of caffeine and alcohol, and pre-bed activities. The second page was completed each morning upon awakening; it asked a series of questions about the pattern of sleep during the preceding night, including bedtime, sleep latency (minutes to fall asleep), number of awakenings during the night, final awakening time, total number of hours slept, and number of nightmares that occurred. Participants were also asked to rate the quality of sleep and their feeling of restedness upon waking on 10-point Likert scales. Diary forms differed for the two treatment groups, including additional questions related to the content of the particular treatment. The Imagery Rehearsal group was asked additional questions each morning about the content of any nightmares and to rate the level of distress related to nightmares on a 10-point Likert scale. The Sleep and Nightmare Management group was asked each night to estimate the number of stressful events that had occurred over the course of the day. No specific definitions or criteria were given for veterans to follow in defining a stressor. Analyses Descriptive statistics for each sleep diary variable were computed. To better understand the nature of sleep disturbance in this sample, the associations between sleep diary variables and
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the baseline measures described above were examined in a series of correlations. The mean of each sleep diary variable was computed for each subject. To avoid overinflation of the Type I error rate, a Bonferroni correction was applied for each set of correlations, resulting in a critical alpha threshold of .01. Sleep characteristics of nights with at least one nightmare (n D 1,862 nights) were then compared to those of nights without any nightmare (n D 1,718 nights) with t-tests. Lastly, in the group that tracked daily stressors, the associations between the number of stressors during the day and sleep characteristics on the subsequent night were computed. The association between number of nightmares at night and number of stressful events the following data was also examined. Analyses between the number of stressful events and sleep characteristics were repeated with baseline CAPS score as a covariate to adjust for the possibility that the stressful event ratings could be inflated as a result of current symptom severity. These analyses utilized mixed models with a random factor for subject and were used to account for repeated observations for each participant. This approach allows the sleep diary variables from each individual 24-hour period to be included, maximizing the prospective nature of the data. The mixed model approach also allows for a different number of observations for each participant in the case of missing data. As such no imputations or other procedures were used to attempt to replace missing data points. Each of the mixed models included subject as a random factor, number of daily stressors as the independent variable, and a sleep diary item as the dependent variable.
RESULTS Sleep diaries were completed by 105 participants, of whom 45 received Imagery Rehearsal therapy and 60 received Sleep and Nightmare Management therapy. Some participants withdrew from treatment (generally near the beginning), and did not complete the full set of diaries. As reported in the primary outcome paper (Cook et al., 2010) medication was stable over treatment for most veterans and there were no significant differences between groups in stability of medication use. The mean (SD) number of days of completed sleep diaries, out of a possible 42, was 35.2 (8.1) for the Imagery Rehearsal group and 34.8 (7.6) for the Sleep and Nightmare Management group, for completion rates of 83.8% and 82.9%, respectively. Descriptive statistics are presented for baseline self-report measures in Table 2 and for sleep diary variables in Table 3. Greater pretreatment PTSD severity as assessed by the PCL-M was associated with more awakenings, shorter sleep time, longer sleep latency, and more nightmares over the six weeks of diary completion. Greater severity of PTSD as assessed by the CAPS was associated with shorter sleep time. Greater severity of depression on the pretreatment BDI was associated with more awakenings and more nightmares. Not surprisingly, worse pretreatment sleep quality as assessed with the PSQI was associated with more awakenings, shorter sleep time, and longer sleep latency. Greater functional interference caused by nightmares, as assessed pretreatment with the NES, was associated with more awakenings, shorter sleep time, longer sleep latency and more nightmares. Table 4 provides the correlation coefficients and p-values for significant associations. Nights with one or more nightmares had more awakenings (2.3 vs. 1.7, t(3578) D 12.8, p < 0.0001), shorter sleep time (5.0 vs. 5.4 hours, t(3548) D 7.7, p < 0.0001), longer sleep
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TABLE 2 Baseline Characteristics of the Sample (Means and SD) Sleep and Nightmare Management
Imagery Rehearsal PSQI total score NES PCL-M BDI CAPS total score
13.2 26.4 62.7 26.9 81.3
(3.2) (9.0) (10.2) (11.8) (14.0)
12.9 24.1 65.1 23.5 79.5
Differences
(3.4) (10.0) (9.5) (11.9) (15.8)
t(112) t(116) t(122) t(119) t(121)
D D D D D
0.59 0.20 0.19 1.55 0.69
PSQI D Pittsburgh Sleep Quality Index; NES = Nightmare Effects Survey; PCL-M D PTSD Checklist Military Version; BDI D Beck Depression Inventory; CAPS D Clinician Administered PTSD Scale.
TABLE 3 Descriptive Statistics for Sleep Diary Variables (Means and SD)
Imagery Rehearsal Number of nightmares Nightmare distress Number of awakenings during the night Total number of hours slept Minutes to fall asleep Sleep quality Number of daily stressors
0.81 1.60 1.96 5.35 39.09 4.60
(0.63) (0.86) (1.13) (1.16) (25.03) (1.04)
Sleep and Nightmare Management 0.83 1.34 1.98 5.00 44.58 4.88 3.94
(0.74) (0.80) (1.00) (1.12) (45.11) (1.32) (2.32)
Differences t(103) D t(102) D t(103) D t(102) D t(102) D t(103) D
0.84 0.12 0.93 0.13 0.47 0.24
TABLE 4 Correlations Between Baseline Measures and Mean Sleep Diary Variables (p Values Provided for All Statistically Significant Effects) Number of Awakenings PSQI total score NES PCL-M BDI CAPS
.31 .29 .34 .36 .16
(p (p (p (p
D D D D
.002) .004) .0007) .0002)
Total Number of Hours Slept .39 .32 .30 .20 .24
(p D .0001) (p D .001) (p D .002) (p D .012)
Minutes to Fall Asleep
Number of Nightmares
.46 (p D .0001) .27 (p D .007) .27 (p D .006) .21 .17
.24 .27 (p D .007) .33 (p D .0005) .33 (p D .0007) .15
PSQI D Pittsburgh Sleep Quality Index; NES D Nightmare Effects Survey; PCL-M D PTSD Checklist Military Version; BDI D Beck Depression Inventory; CAPS D Clinician Administered PTSD Scale.
SLEEP DIARIES OF VIETNAM WAR VETERANS
FIGURE 1
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Association between daily stressors and nightmares.
latency (44.8 vs. 32.8 minutes, t(3380) D 9.1, p < 0.0001), and lower sleep quality (4.3 vs. 5.3 out of 10, t(3572) D 17.0, p < 0.0001) compared to nights without nightmares. There were significant associations between the number of daily stressors and sleep latency (F(1,1634) D 5.5, p D .02), number of nightmares (F(1,1712) D 5.9, p D .016), and distress from nightmares (F(1,1673) D 4.7, p D .03; see Figure 1). The number of stressors was not significantly associated with the number of awakenings, total sleep time, or perceived sleep quality. The number of nightmares at night was not significantly associated with ratings of stressor frequency the following day. This pattern of results was the same when total CAPS score was included as a covariate.
DISCUSSION This study examined six weeks of daily sleep diary data from Vietnam War veterans with severe, chronic PTSD participating in a randomized trial of cognitive-behavioral sleep and nightmare treatment. The focus of the study was threefold. First, we aimed to examine the relationships between sleep characteristics and baseline symptomatology. Second, we compared measures of sleep continuity between nights with and without at least one nightmare. Finally we investigated associations between daily ratings of the frequency of stressors and measures of sleep at night. Rates of diary completion were high in both treatment groups, with data available for more than 80% of nights. Veterans rated their sleep as significantly disturbed and generally of poor quality, with an average sleep onset latency longer than 30 min and an approximate total sleep
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time of five hours. Veterans reported on experiencing, on average, 0.8 nightmares per night, or a nightmare on five to six nights per week. This is consistent with the sizeable literature documenting the high prevalence of sleep disturbance in veterans with PTSD (Kilpatrick et al., 1997; Neylan et al., 1998). It should be kept in mind, however, that these participants were a treatment-seeking sample, engaged in a clinical trial of a sleep-focused treatment, in which only veterans with disturbed sleep were included. Thus, these numbers may not be reflective of the overall population of Vietnam War veterans with PTSD. It was somewhat surprising that average ratings of nightmare distress were quite low. A more thorough investigation of nightmares and related distress is warranted to clarify the meaning of this finding. The severity of veterans’ sleep disturbance varied with PTSD severity: Veterans with greater PTSD symptomatology on the PCL-M had worse sleep across all sleep diary variables, supporting prior retrospective research (Babson et al., 2011). Associations with the CAPS, on the other hand, were not statistically significant. This discrepancy between the results of the PCL-M and the CAPS may reflect different sources of method variance, that is, the association was stronger between two self-reported measures but weaker between one self-report and one clinician-administered measure. Greater depression severity was also associated with worse sleep, but only for the number of awakenings and number of nightmares. Lending support to the validity of the data, there were strong associations between sleep parameters and the PSQI and NES. The prospective sleep diary methodology permitted a novel comparison of sleep parameters on nights with and without nightmares. Nights with nightmares were characterized as having more awakenings, less total sleep time, and lower perceived sleep quality. Interestingly, sleep latency was also significantly longer on nights with nightmares. The latter finding suggests that nights with nightmares begin with heightened physiologic and emotional arousal, which later in the sleep period manifests as one or more nightmares. The sleep diary data in the Sleep and Nightmare Management group allowed for prospective assessment of the relationships between daily ratings of the frequency of stressful events and subsequent sleep. It is intuitive that greater frequency of stressors during the day leads to disrupted sleep at night. However, sleep latency was the only sleep continuity measure that was positively associated with the number of daytime stressors. As expected, we found that a greater number of daytime stressors was associated with more frequent nightmares and greater nightmare-related distress. This is consistent with Levin and Nielsen’s (2007) review of the relationship between anxiety and nightmare distress. A higher number of daytime stressors may lead to moderate physiologic or emotional hyperarousal at bedtime, thereby interfering with sleep onset. This hyperarousal may persist into the early part of the sleep period and increase the likelihood of producing a nightmare, but may not be of sufficient intensity to disrupt sleep throughout the night. This may explain the observation in past studies that PTSD-related nightmares often occur in the early part of the night, despite the fact that most REM sleep tends to occur in the latter part of the night (Ross et al., 1989). However it is in contrast to the finding of Babson et al. (2011) that the hyperarousal symptoms of PTSD are associated with trouble maintaining sleep and nightmares, but not with initiating sleep. It would be interesting in future studies to monitor physiologic markers of arousal such as heart rate and galvanic skin response throughout the sleep period. There are several strengths of this study, in particular the prospective nature of sleep and nightmare assessment, which is an improvement upon single time point retrospective estimates.
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Furthermore, the completion of sleep diaries over a six-week period allows more extensive investigation of relationships across days and nights than would be feasible using a typical one-week monitoring period. A limitation of this study is that, in order to reduce participant burden, some standard sleep diary variables, such as wakefulness after sleep onset, were not included. In addition, these data have the limitations of typical self-report measures in terms of bias, and it will be important to examine more objective measures of sleep, as obtained from actigraphy, in future studies. Another limitation of the study is the way that stress was assessed. The sleep diary item for the number of stressful events was created solely for clinical purposes and was not designed to provide a valid measure of perceived stress. Thus, veterans were not given explicit instructions in how to define a stressor and there was likely intersubject variability in how this item on the sleep diary was interpreted. Self-reported stress levels can also be highly inflated and related to current emotional state. To examine this possibility, analyses of stress ratings were repeated with baseline CAPS score as a covariate to control for current severity and the results were unchanged. We plan to follow up this study with a future investigation of the relationship between daytime stress and nocturnal sleep in veterans with PTSD that utilizes validated methods for stress assessment to address the limitations of this study. The nature of the clinical trial study design with specific eligibility criteria and treatment effects may have introduced biases to estimates of sleep parameters and, as such, it should not be assumed that these values are representative of the broader population of veterans with PTSD. While there were not substantial changes in medication use over the course of treatment, it is possible that the changes that did occur had an impact on these results. In summary, these prospective findings add to accumulating evidence of disturbed sleep patterns in veterans with PTSD. Many of the results empirically substantiate commonly held and intuitive beliefs about relationships between sleep variables, such as poorer-quality sleep on nights with nightmares compared to nights without nightmares and increased nightmare frequency and distress following days with higher frequency of stressful events. However, some of the findings, such as the absence of evidence for an impact of number of daily stressors on sleep continuity, are counterintuitive. The results suggest that treatments that target presleep hyperarousal using somatic (e.g., progressive muscle relaxation) and cognitive (e.g., worry time exercises) procedures may be effective in reducing sleep latency and nightmare frequency and distress.
FUNDING This project was supported by the Office of Research and Development, Department of Veterans Affairs. The content of this article does not represent the views of the Department of Veterans Affairs or of the U.S. Government.
REFERENCES Babson, K., Feldner, M., Badour, C., Trainor, C., Blumenthal, H., Sachs-Ericsson, N., & Schmidt, N. (2011). Posttraumatic stress and sleep: Differential relations across types of symptoms and sleep problems. Journal of Anxiety Disorders, 25(5), 706–713. doi:10.1016/j.janxdis.2011.03.007
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Beck, A. T. & Steer, R. A. (1987). Manual for the Revised Beck Depression Inventory. San Antonio, TX: Psychological Corporation. Belleville, G., Guay, S., & Marchand, A. (2011). Persistence of sleep disturbances following cognitive-behavior therapy for posttraumatic stress disorder. Journal of Psychosomatic Research, 70(4), 318–327. doi:10.1016/j.jpsychores.2010. 09.022 Blake, D. D., Weathers, F. W., Nagy, L. M., Kaloupek, D. G., Gusman, F. D., Charney, D. S., & Keane, T. M. (1995). The development of a Clinician-Administered PTSD scale. Journal of Traumatic Stress, 8, 75–90. Buysse, D. J., Reynolds, C. F., III, Monk, T. H., Berman, S. R., & Kupfer, D. J. (1989). The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Research, 128, 193–213. Cook, J. M., Harb, G. C., Gehrman, P. R., Cary, M. S., Gamble, G. M., Forbes, D., & Ross, R. J. (2010). Imagery Rehearsal for posttraumatic nightmares: A randomized controlled trial. Journal of Traumatic Stress, 23(5), 553–563. Galovski, T. E., Monson, C. M., Baker, D. G., Sikes, C. R., & Farfel, G. M. (2009). Does cognitive-behavioral therapy for PTSD improve perceived health and sleep impairment? Journal of Traumatic Stress, 22, 197–204. Healey, E. S., Kales, A., Monroe, L. J., Bixler, E. O., Chamberlin, K., & Soldatos, C. R. (1981). Onset of insomnia: Role of life-stress events. Psychosomatic Medicine, 43, 439–451. Krakow, B., Hollified, M., Schrader, R., Koss, M., Tandberg, D., Lauriello, J., : : : Kellner, R. (2000). A controlled study of imagery rehearsal for chronic nightmares in sexual assault survivors with PTSD: A preliminary report. Journal of Traumatic Stress, 13, 589–609. Lancee, J., Spoormaker, V. I., Perese, G., & van den Bout, J. (2008). Measuring nightmare frequency: Retrospective questionnaires versus prospective logs. Open Sleep Journal, 1, 26–28. Levin, R., & Nielsen, T. A. (2007). Disturbed dreaming, posttraumatic stress disorder, and affect distress: A review and neurocognitive model. Psychological Bulletin, 133, 482–528. Maislin, G., Pack, A. I., Kribbs, N. B., Smith, P. L., Schwartz, A. R., Kline, L. R., : : : Dinges, D. F. (1995). A survey screen for prediction of sleep apnea. Sleep, 18, 158–66. Nappi, C. M., Drummond, S. P. A., & Hall, J. M. H. (2012). Treating nightmares and insomnia in posttraumatic stress disorder: A review of current evidence. Neuropharmacology, 62(2), 576–585. doi:10.1016/j.neuropharm.2011. 02.029 Neylan, T. C., Marmar, C. R., Metzler, T. J., Weiss, D. S., Zatzick, D. F., Delucchi, K. L., : : : Schoenfeld, F. B. (1998). Sleep disturbances in the Vietnam generation: Findings from a nationally representative sample of male Vietnam veterans. American Journal of Psychiatry, 155, 929–993. Perlis, M. L., Swinkels, C. M., Gehrman, P. R., Pigeon, W. R., Matteson-Rusby, S. E., & Jungquist, C. R. (2010). The incidence and temporal patterning of insomnia: A pilot study. Journal of Sleep Research, 19, 31–35. Ross, R. J., Ball, W. A., Sullivan, K. A., & Caroff, S. N. (1989). Sleep disturbance as the hallmark of posttraumatic stress disorder. American Journal of Psychiatry, 146, 697–707. Stone, A. A., & Shiffman, S. (2002). Capturing momentary, self-report data: A proposal for reporting guidelines. Annals of Behavioral Medicine, 24(3): 236–243. Weathers, F. W., Litz, B. T., Herman, D. S., Huska, J. A., & Keane, T. M. (1993, October). The PTSD Checklist (PCL): Reliability, validity, and diagnostic utility. Paper presented at the meeting of the International Society for Traumatic Stress Studies, San Antonio, TX. Zadra, A., & Donderi, D. C. (2000). Nightmares and bad dreams: Their prevalence and relationship to well-being. Journal of Applied Psychology, 109, 273–281. Zayfert, C., & DeViva, J. C. (2004). Residual insomnia following cognitive behavioral therapy for PTSD. Journal of Traumatic Stress, 17, 69–73.
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Sleep Diaries of Vietnam War Veterans With Chronic PTSD: The Relationships Among Insomnia Symptoms, Psychosocial Stress, and Nightmares Philip R. Gehrman Philadelphia Veterans Affairs Medical Center; Department of Psychiatry University of Pennsylvania
Gerlinde C. Harb Philadelphia Veterans Affairs Medical Center
Joan M. Cook Yale University; National Center for PTSD, Boston
Holly Barilla University of Pennsylvania
Richard J. Ross Philadelphia Veterans Affairs Center; Department of Psychiatry University of Pennsylvania Impaired sleep and nightmares are known symptoms of posttraumatic stress disorder (PTSD) in the veteran population. In order to assess prospectively the sleep disturbances in this population, sleep diaries are an effective way to obtain information over an extended period of time. In this investigation, a sample of veterans (N D 105) completed daily sleep diaries for a 6-week period. Greater PTSD severity and nightmare-related distress were correlated with more awakenings, shorter duration of sleep, longer sleep latency, and greater frequency of nightmares. Perceived frequency of daytime stressors was associated with an increased number of nightmares, nightmarerelated distress, and longer sleep latency. The use of sleep diaries in future investigations may allow targeted treatments for veteran populations with PTSD and sleep disturbances. Correspondence should be addressed to Philip Gehrman, PhD, Department of Psychiatry, University of Pennsylvania, 3535 Market Street, Suite 670, Philadelphia, PA 19104. E-mail: [email protected]
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Understanding and treating the sleep disturbances related to posttraumatic stress disorder (PTSD) has recently received increased attention (Nappi et al., 2012). Two of the most common symptoms of PTSD are recurrent nightmares and insomnia (Neylan et al., 1998). These forms of sleep disturbance cause significant distress and impairment in daytime functioning (Levin & Nielsen, 2007; Neylan et al., 1998; Zadra & Donderi, 2000), and are very often difficult to treat (Belleville, Guay, & Marchand, 2011; Galovski, Monson, Bruce, & Resick, 2009; Zayfert & DeViva, 2004). Sleep disturbance seems to be particularly common in PTSD related to military trauma (Neylan et al., 1998). Research on the sleep disturbances in PTSD has relied almost entirely on retrospective assessments of sleep using standardized self-report questionnaires. Retrospective assessments can be strongly influenced by a number of self-report biases, such as the tendency to be overly influenced by atypical events (Stone & Shiffman, 2002). Prospective assessment of sleep characteristics can reduce the impact of self-report biases and yield more accurate information. For example, Lancee and colleagues (2008) found significant differences in nightmare frequency between retrospective questionnaires and prospective daily logs. In this sample of college students, the use of retrospective questionnaires led to systematic underreporting of nightmare frequency. Prospective assessment of sleep characteristics is routinely accomplished using daily sleep diaries, for which respondents are instructed to answer a series of questions pertaining to sleep/wake the preceding night shortly after awakening. Although sleep and nightmare diaries are routinely utilized in clinical trials of sleep-focused treatments in PTSD populations, rarely are these data reported on or investigated in detail. A particular value of prospective assessment using sleep diaries is the opportunity to examine temporal relationships among variables that can be measured on a regular basis. Although veterans with PTSD experience poor sleep overall, there is likely night-to-night variability in severity as has been documented in individuals with primary insomnia (Perlis et al., 2010). One potential source of variability is participants’ daytime experiences. Self-reported stress levels are known to correlate with sleep disturbance across individuals (Healey et al., 1981). It would be reasonable to suspect that, within an individual, days with higher levels of stress would be followed by worse sleep and more nightmares the following night. Prospective assessment of sleep and stress levels would permit this and other, related questions to be examined. The goal of this investigation was to conduct analyses of sleep diary data collected as part of a clinical trial of psychological sleep-focused treatment in a sample of veterans with PTSD. The data were examined with regard to patterns of sleep and nightmares overall and within days. It was hypothesized that greater severity of PTSD would be associated with poorer sleep, and that days with higher frequency of daily stressors would be associated with worse sleep at night.
METHODS Participants The data for these analyses are taken from a larger randomized, controlled trial of two psychological therapies for Vietnam War veterans with severe, chronic PTSD (Cook et al., 2010). For that trial, 156 male Vietnam War veterans receiving mental health services at the Philadelphia Veterans Affairs (VA) Medical Center were screened for eligibility; inclusion
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TABLE 1 Participants’ Baseline Sociodemographics and Clinical Characteristics
Age (Mean [SD]) Ethnicity Caucasian African American Other Education Did not complete high school Graduated from high school Completed some college Employment Full or part-time Retired Unemployed Combat Exposure Scale (Mean [SD]) Note.
Imagery Rehearsal n D 61
Sleep and Nightmare Management n D 63
59.79 (3.18)
59.06 (3.86)
27 (44.3) 30 (49.2) 4 (6.6)
25 (39.7) 34 (54.0) 4 (6.4)
10 (16.4) 23 (37.7) 28 (45.9)
9 (14.3) 26 (41.3) 17 (44.5)
6 (9.8) 34 (55.7) 21 (34.4) 29.27 (9.23)
16 (26.2) 29 (47.5) 16 (26.2) 29.31 (7.79)
Differences t(122) D 1.14 2 .2; N D 124/ D 0:3
2 .3; N D 124/ D 1:51
2 .3; N D 122/ D 6:0
t.88/ D 1:14; p D 0:26
All cells show n and percentage, unless otherwise noted. *p < .05; **p < .01.
criteria were: male gender, diagnosis of current PTSD due to combat in Vietnam as assessed with the Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995), currently experiencing combat-related nightmares at least once a week for greater than six months, and clinically significant sleep disturbance as indicated by a global score of five or more on the Pittsburgh Sleep Quality Index (PSQI; Buysse, Reynolds, Monk, Berman, & Kupfer, 1989). Comorbid major depression and/or an anxiety disorder other than PTSD were allowed. Individuals taking psychoactive medications were required to be on a stable regimen for a minimum of three months before they were eligible to participate. Exclusion criteria were: schizophrenia and other psychotic disorders, bipolar disorder, active substance abuse or dependence in the past six months, and medical disorders known to impact sleep (e.g., narcolepsy). Participants for whom there was a high suspicion of undiagnosed sleep apnea based on the Multivariable Apnea Predictor (MAP; Maislin et al., 1995) were also excluded. Of the 156 men evaluated for eligibility, 18 did not meet study criteria, 4 elected not to participate after evaluation but prior to consenting, and 10 withdrew before being assigned to a treatment condition. The final sample consisted of 124 veterans who were randomized to receive either one of two cognitive-behavioral therapies, Imagery Rehearsal (n D 61) or Sleep and Nightmare Management (n D 63). The study did not find significant improvements in nightmares as a result of these treatments, although both produced improvements in sleep quality and PTSD severity. Demographic information describing the sample is provided in Table 1. Procedure Participants were recruited for the IRB-approved clinical trial with the assistance of mental health clinic providers and flyers posted in waiting room areas. After giving written informed
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consent, veterans completed a self-report battery at baseline and had an interview with a clinical psychologist, who administered the SCID-IV-P and the CAPS to confirm a diagnosis of PTSD. When a sufficient number of veterans (6 to 10) were recruited to form two therapy groups (one for Sleep and Nightmare Management and one for Imagery Rehearsal), participants were randomly assigned to one of the treatment conditions. Both treatments were delivered according to manualized protocols. Treatment was conducted in group format, in six weekly 90-min sessions. Medication use was tracked throughout treatment. Measures The PSQI is a widely used 19-item self-report measure of sleep quality and sleep disturbances during the past month. The items generate seven component scores, each ranging from 0 to 3. The sum of the scores for the seven components yields one global score, which ranges from 0 to 21, with higher scores indicating worse sleep quality. The Nightmare Effects Survey (NES) is an 11-item measure used to assess psychosocial impairment attributed to nightmares, rated on a 5-point scale (Krakow et al., 2000). Scores range from 0 to 44, with higher scores indicating greater impairment and distress due to nightmares. The PTSD Checklist-Military (PCL-M) is a 17-item measure of PTSD symptoms based on DSM-IV criteria for PTSD (Weathers, Litz, Herman, Huska, & Keane, 1993). Using a 5-point Likert scale, subjects indicate the extent to which they have experienced each symptom in the past month. Scores range from 17 to 75, with higher scores indicating more severe PTSD. The Beck Depression Inventory (BDI) is a measure of cognitive, affective, and somatic symptoms of depression (Beck & Steer, 1987). The BDI is a 21-item self-report measure in which individuals choose the statement that best describes the way they have been feeling during the past week. Scores range from 0 to 63, with higher scores indicating more severe depression. Throughout treatment, participants completed daily sleep diaries that were divided into two parts. The first page was completed at night before going to bed; it asked about napping during the day, consumption of caffeine and alcohol, and pre-bed activities. The second page was completed each morning upon awakening; it asked a series of questions about the pattern of sleep during the preceding night, including bedtime, sleep latency (minutes to fall asleep), number of awakenings during the night, final awakening time, total number of hours slept, and number of nightmares that occurred. Participants were also asked to rate the quality of sleep and their feeling of restedness upon waking on 10-point Likert scales. Diary forms differed for the two treatment groups, including additional questions related to the content of the particular treatment. The Imagery Rehearsal group was asked additional questions each morning about the content of any nightmares and to rate the level of distress related to nightmares on a 10-point Likert scale. The Sleep and Nightmare Management group was asked each night to estimate the number of stressful events that had occurred over the course of the day. No specific definitions or criteria were given for veterans to follow in defining a stressor. Analyses Descriptive statistics for each sleep diary variable were computed. To better understand the nature of sleep disturbance in this sample, the associations between sleep diary variables and
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259
the baseline measures described above were examined in a series of correlations. The mean of each sleep diary variable was computed for each subject. To avoid overinflation of the Type I error rate, a Bonferroni correction was applied for each set of correlations, resulting in a critical alpha threshold of .01. Sleep characteristics of nights with at least one nightmare (n D 1,862 nights) were then compared to those of nights without any nightmare (n D 1,718 nights) with t-tests. Lastly, in the group that tracked daily stressors, the associations between the number of stressors during the day and sleep characteristics on the subsequent night were computed. The association between number of nightmares at night and number of stressful events the following data was also examined. Analyses between the number of stressful events and sleep characteristics were repeated with baseline CAPS score as a covariate to adjust for the possibility that the stressful event ratings could be inflated as a result of current symptom severity. These analyses utilized mixed models with a random factor for subject and were used to account for repeated observations for each participant. This approach allows the sleep diary variables from each individual 24-hour period to be included, maximizing the prospective nature of the data. The mixed model approach also allows for a different number of observations for each participant in the case of missing data. As such no imputations or other procedures were used to attempt to replace missing data points. Each of the mixed models included subject as a random factor, number of daily stressors as the independent variable, and a sleep diary item as the dependent variable.
RESULTS Sleep diaries were completed by 105 participants, of whom 45 received Imagery Rehearsal therapy and 60 received Sleep and Nightmare Management therapy. Some participants withdrew from treatment (generally near the beginning), and did not complete the full set of diaries. As reported in the primary outcome paper (Cook et al., 2010) medication was stable over treatment for most veterans and there were no significant differences between groups in stability of medication use. The mean (SD) number of days of completed sleep diaries, out of a possible 42, was 35.2 (8.1) for the Imagery Rehearsal group and 34.8 (7.6) for the Sleep and Nightmare Management group, for completion rates of 83.8% and 82.9%, respectively. Descriptive statistics are presented for baseline self-report measures in Table 2 and for sleep diary variables in Table 3. Greater pretreatment PTSD severity as assessed by the PCL-M was associated with more awakenings, shorter sleep time, longer sleep latency, and more nightmares over the six weeks of diary completion. Greater severity of PTSD as assessed by the CAPS was associated with shorter sleep time. Greater severity of depression on the pretreatment BDI was associated with more awakenings and more nightmares. Not surprisingly, worse pretreatment sleep quality as assessed with the PSQI was associated with more awakenings, shorter sleep time, and longer sleep latency. Greater functional interference caused by nightmares, as assessed pretreatment with the NES, was associated with more awakenings, shorter sleep time, longer sleep latency and more nightmares. Table 4 provides the correlation coefficients and p-values for significant associations. Nights with one or more nightmares had more awakenings (2.3 vs. 1.7, t(3578) D 12.8, p < 0.0001), shorter sleep time (5.0 vs. 5.4 hours, t(3548) D 7.7, p < 0.0001), longer sleep
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TABLE 2 Baseline Characteristics of the Sample (Means and SD) Sleep and Nightmare Management
Imagery Rehearsal PSQI total score NES PCL-M BDI CAPS total score
13.2 26.4 62.7 26.9 81.3
(3.2) (9.0) (10.2) (11.8) (14.0)
12.9 24.1 65.1 23.5 79.5
Differences
(3.4) (10.0) (9.5) (11.9) (15.8)
t(112) t(116) t(122) t(119) t(121)
D D D D D
0.59 0.20 0.19 1.55 0.69
PSQI D Pittsburgh Sleep Quality Index; NES = Nightmare Effects Survey; PCL-M D PTSD Checklist Military Version; BDI D Beck Depression Inventory; CAPS D Clinician Administered PTSD Scale.
TABLE 3 Descriptive Statistics for Sleep Diary Variables (Means and SD)
Imagery Rehearsal Number of nightmares Nightmare distress Number of awakenings during the night Total number of hours slept Minutes to fall asleep Sleep quality Number of daily stressors
0.81 1.60 1.96 5.35 39.09 4.60
(0.63) (0.86) (1.13) (1.16) (25.03) (1.04)
Sleep and Nightmare Management 0.83 1.34 1.98 5.00 44.58 4.88 3.94
(0.74) (0.80) (1.00) (1.12) (45.11) (1.32) (2.32)
Differences t(103) D t(102) D t(103) D t(102) D t(102) D t(103) D
0.84 0.12 0.93 0.13 0.47 0.24
TABLE 4 Correlations Between Baseline Measures and Mean Sleep Diary Variables (p Values Provided for All Statistically Significant Effects) Number of Awakenings PSQI total score NES PCL-M BDI CAPS
.31 .29 .34 .36 .16
(p (p (p (p
D D D D
.002) .004) .0007) .0002)
Total Number of Hours Slept .39 .32 .30 .20 .24
(p D .0001) (p D .001) (p D .002) (p D .012)
Minutes to Fall Asleep
Number of Nightmares
.46 (p D .0001) .27 (p D .007) .27 (p D .006) .21 .17
.24 .27 (p D .007) .33 (p D .0005) .33 (p D .0007) .15
PSQI D Pittsburgh Sleep Quality Index; NES D Nightmare Effects Survey; PCL-M D PTSD Checklist Military Version; BDI D Beck Depression Inventory; CAPS D Clinician Administered PTSD Scale.
SLEEP DIARIES OF VIETNAM WAR VETERANS
FIGURE 1
261
Association between daily stressors and nightmares.
latency (44.8 vs. 32.8 minutes, t(3380) D 9.1, p < 0.0001), and lower sleep quality (4.3 vs. 5.3 out of 10, t(3572) D 17.0, p < 0.0001) compared to nights without nightmares. There were significant associations between the number of daily stressors and sleep latency (F(1,1634) D 5.5, p D .02), number of nightmares (F(1,1712) D 5.9, p D .016), and distress from nightmares (F(1,1673) D 4.7, p D .03; see Figure 1). The number of stressors was not significantly associated with the number of awakenings, total sleep time, or perceived sleep quality. The number of nightmares at night was not significantly associated with ratings of stressor frequency the following day. This pattern of results was the same when total CAPS score was included as a covariate.
DISCUSSION This study examined six weeks of daily sleep diary data from Vietnam War veterans with severe, chronic PTSD participating in a randomized trial of cognitive-behavioral sleep and nightmare treatment. The focus of the study was threefold. First, we aimed to examine the relationships between sleep characteristics and baseline symptomatology. Second, we compared measures of sleep continuity between nights with and without at least one nightmare. Finally we investigated associations between daily ratings of the frequency of stressors and measures of sleep at night. Rates of diary completion were high in both treatment groups, with data available for more than 80% of nights. Veterans rated their sleep as significantly disturbed and generally of poor quality, with an average sleep onset latency longer than 30 min and an approximate total sleep
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time of five hours. Veterans reported on experiencing, on average, 0.8 nightmares per night, or a nightmare on five to six nights per week. This is consistent with the sizeable literature documenting the high prevalence of sleep disturbance in veterans with PTSD (Kilpatrick et al., 1997; Neylan et al., 1998). It should be kept in mind, however, that these participants were a treatment-seeking sample, engaged in a clinical trial of a sleep-focused treatment, in which only veterans with disturbed sleep were included. Thus, these numbers may not be reflective of the overall population of Vietnam War veterans with PTSD. It was somewhat surprising that average ratings of nightmare distress were quite low. A more thorough investigation of nightmares and related distress is warranted to clarify the meaning of this finding. The severity of veterans’ sleep disturbance varied with PTSD severity: Veterans with greater PTSD symptomatology on the PCL-M had worse sleep across all sleep diary variables, supporting prior retrospective research (Babson et al., 2011). Associations with the CAPS, on the other hand, were not statistically significant. This discrepancy between the results of the PCL-M and the CAPS may reflect different sources of method variance, that is, the association was stronger between two self-reported measures but weaker between one self-report and one clinician-administered measure. Greater depression severity was also associated with worse sleep, but only for the number of awakenings and number of nightmares. Lending support to the validity of the data, there were strong associations between sleep parameters and the PSQI and NES. The prospective sleep diary methodology permitted a novel comparison of sleep parameters on nights with and without nightmares. Nights with nightmares were characterized as having more awakenings, less total sleep time, and lower perceived sleep quality. Interestingly, sleep latency was also significantly longer on nights with nightmares. The latter finding suggests that nights with nightmares begin with heightened physiologic and emotional arousal, which later in the sleep period manifests as one or more nightmares. The sleep diary data in the Sleep and Nightmare Management group allowed for prospective assessment of the relationships between daily ratings of the frequency of stressful events and subsequent sleep. It is intuitive that greater frequency of stressors during the day leads to disrupted sleep at night. However, sleep latency was the only sleep continuity measure that was positively associated with the number of daytime stressors. As expected, we found that a greater number of daytime stressors was associated with more frequent nightmares and greater nightmare-related distress. This is consistent with Levin and Nielsen’s (2007) review of the relationship between anxiety and nightmare distress. A higher number of daytime stressors may lead to moderate physiologic or emotional hyperarousal at bedtime, thereby interfering with sleep onset. This hyperarousal may persist into the early part of the sleep period and increase the likelihood of producing a nightmare, but may not be of sufficient intensity to disrupt sleep throughout the night. This may explain the observation in past studies that PTSD-related nightmares often occur in the early part of the night, despite the fact that most REM sleep tends to occur in the latter part of the night (Ross et al., 1989). However it is in contrast to the finding of Babson et al. (2011) that the hyperarousal symptoms of PTSD are associated with trouble maintaining sleep and nightmares, but not with initiating sleep. It would be interesting in future studies to monitor physiologic markers of arousal such as heart rate and galvanic skin response throughout the sleep period. There are several strengths of this study, in particular the prospective nature of sleep and nightmare assessment, which is an improvement upon single time point retrospective estimates.
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Furthermore, the completion of sleep diaries over a six-week period allows more extensive investigation of relationships across days and nights than would be feasible using a typical one-week monitoring period. A limitation of this study is that, in order to reduce participant burden, some standard sleep diary variables, such as wakefulness after sleep onset, were not included. In addition, these data have the limitations of typical self-report measures in terms of bias, and it will be important to examine more objective measures of sleep, as obtained from actigraphy, in future studies. Another limitation of the study is the way that stress was assessed. The sleep diary item for the number of stressful events was created solely for clinical purposes and was not designed to provide a valid measure of perceived stress. Thus, veterans were not given explicit instructions in how to define a stressor and there was likely intersubject variability in how this item on the sleep diary was interpreted. Self-reported stress levels can also be highly inflated and related to current emotional state. To examine this possibility, analyses of stress ratings were repeated with baseline CAPS score as a covariate to control for current severity and the results were unchanged. We plan to follow up this study with a future investigation of the relationship between daytime stress and nocturnal sleep in veterans with PTSD that utilizes validated methods for stress assessment to address the limitations of this study. The nature of the clinical trial study design with specific eligibility criteria and treatment effects may have introduced biases to estimates of sleep parameters and, as such, it should not be assumed that these values are representative of the broader population of veterans with PTSD. While there were not substantial changes in medication use over the course of treatment, it is possible that the changes that did occur had an impact on these results. In summary, these prospective findings add to accumulating evidence of disturbed sleep patterns in veterans with PTSD. Many of the results empirically substantiate commonly held and intuitive beliefs about relationships between sleep variables, such as poorer-quality sleep on nights with nightmares compared to nights without nightmares and increased nightmare frequency and distress following days with higher frequency of stressful events. However, some of the findings, such as the absence of evidence for an impact of number of daily stressors on sleep continuity, are counterintuitive. The results suggest that treatments that target presleep hyperarousal using somatic (e.g., progressive muscle relaxation) and cognitive (e.g., worry time exercises) procedures may be effective in reducing sleep latency and nightmare frequency and distress.
FUNDING This project was supported by the Office of Research and Development, Department of Veterans Affairs. The content of this article does not represent the views of the Department of Veterans Affairs or of the U.S. Government.
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