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Transcript
Characteristics of Chronic Nightmares in a
Trauma-Exposed Treatment-Seeking Sample
Joanne L. Davis, Patricia Byrd, and Jamie L. Rhudy
University of Tulsa
David C. Wright
United States Air Force
Chronic nightmares pose a significant problem for many individuals affected
by trauma. The present study attempts to extend current knowledge on the
nature, characteristics, and associated sequelae of chronic nightmares. Data
were collected from 94 trauma-exposed, treatment-seeking participants (74
women and 20 men). These data suggest that most participants reported their
nightmares to be similar or dissimilar to their traumatic experience rather
than exact replications (replicative). Not surprisingly, though, nightmarerelated distress was positively related to the degree of similarity between their
nightmare and their trauma, with replicative nightmares eliciting the greatest
distress. Persons with a current diagnosis of posttraumatic stress disorder
(PTSD) were more likely to report problems related to nightmares and sleep
disturbance than persons without current PTSD. Nonetheless, even after
controlling for PTSD-related symptomatology, frequency and severity of
nightmares significantly predicted some distress outcomes (e.g., poor sleep
quality), suggesting that nightmares contribute to psychological distress
above and beyond PTSD symptoms. Implications for future research, and for
the treatment of nightmares and PTSD, are discussed.
Keywords: nightmares, posttraumatic stress disorder, trauma
Nightmares are a pernicious and common complaint reported by individuals
affected by trauma. Research has found that chronic posttraumatic nightmares are
related to the presence and severity of posttraumatic symptoms (David & Mellman,
1997; Mellman, David, Bustamante, Torres, & Fins, 2001; Schreuder, Kleijn, &
Joanne L. Davis, Patricia Byrd, and Jamie L. Rhudy, Department of Psychology, University of
Tulsa; David C. Wright, United States Air Force.
The activities described were supported by an OHRS award for project number HR02-002S from
the Oklahoma Center for the Advancement of Science and Technology, by the Psi Chi National Honor
Society, and by the University of Tulsa’s Office of Research and Sponsored Programs internal funding.
Portions of this article were presented at the annual meetings of the following organizations: the
Association for the Advancement of Behavior Therapy, the Oklahoma Psychological Association, and
the Disaster Mental Health Institute. We wish to express our appreciation to the members of the
Trauma Research: Assessment, Prevention, and Treatment Center for their assistance with this project.
Correspondence concerning this article should be addressed to Joanne L. Davis, 600 South College
Avenue, University of Tulsa, Tulsa, OK 74104. E-mail: [email protected]
187
Dreaming
2007, Vol. 17, No. 4, 187–198
Copyright 2007 by the American Psychological Association
1053-0797/07/$12.00 DOI: 10.1037/1053-0797.17.4.187
188
Davis, Byrd, Rhudy, and Wright
Rooijmans, 2000; van der Kolk, Blitz, Burr, Sherry, & Hartmann, 1984), and
nightmares may differ in persons with and without posttraumatic stress disorder
(PTSD; e.g., Mellman, Kulick-Bell, Ashlock, & Nolan, 1995). The majority of
studies examining characteristics of chronic nightmares have used combat populations; thus, much less is known about chronic nightmares in those exposed to
civilian trauma. The purpose of this article is to explore the nature and characteristics of chronic nightmares in a clinical sample of diverse trauma-exposed persons
with and without PTSD.
The majority of studies on nightmares in trauma-exposed samples have focused on their prevalence, content, and association with PTSD. “Trauma nightmares” or “PTSD nightmares” are generally thought of as being exact replays (i.e.,
replicative) of a traumatic event. Indeed, Ross, Ball, Sullivan, and Caroff (1989)
suggested that replicative nightmares were specific to PTSD. However, most of the
research has failed to make a distinction between nightmares that are exact replays
of the trauma and those that are only similar to the trauma. This has made it
difficult to determine the prevalence of nightmares based on their similarity to the
traumatic event (i.e., replicative, trauma similar, trauma dissimilar) and whether the
degree of similarity affects distress. Furthermore, it remains unclear whether such
trauma-similarity distinctions are clinically or empirically important.
Several studies have found that replicative or trauma-similar nightmares are
associated with severity of PTSD symptoms (Mellman et al., 2001, 1995; Schreuder
et al., 2000; van der Kolk et al., 1984). Esposito, Benitez, Barza, and Mellman
(1999) analyzed dream content in 18 combat veterans with PTSD and found that
approximately half of the sample experienced dreams with content similar to
combat. A relationship was also found between trauma-similar dreams and severity
of reexperiencing symptoms of PTSD. Mellman et al. (1995) sampled 58 combat
veterans, 37 of whom met criteria for PTSD, and found that veterans with PTSD
were more likely to report having nightmares with combat content than those
without PTSD. Similarly, van der Kolk et al. (1984) assessed 15 combat veterans
with PTSD and 10 noncombat veterans without PTSD but who reported lifelong nightmares. Eleven veterans with PTSD and none without PTSD reported having nightmares
that replicated a traumatic event. Moreover, all 15 of the veterans with PTSD reported
having repetitive nightmares compared with 3 individuals without PTSD. So although the
veterans without PTSD reported a lifelong problem with nightmares, their nightmares did
not replicate an actual event and generally did not repeat over time.
Limited research has examined the association of nightmares and PTSD
among survivors of civilian trauma. David and Mellman (1997) researched 32
victims of Hurricane Andrew (20 of whom met criteria for PTSD) 6 to 12 months
after the disaster who recalled a dream within the past month. Although significant
differences were not found between those who met criteria for PTSD and those
who did not, replicative nightmares (referred to as dreams by the authors) were
only reported by those who met criteria for PTSD. Similarly, Mellman et al. (2001)
assessed dreams and PTSD in 39 patients admitted to a hospital following a
life-threatening event (e.g., motor vehicle accident, industrial accident, and interpersonal assault) and again 6 weeks later. Dreams were considered “trauma
dreams” if raters indicated they were moderately to exactly similar to the traumatic
event and moderately to extremely disturbing. From the 21 dreams reported, 10
were categorized as trauma dreams. The remaining dreams were either distressing
Characteristics of Chronic Nightmares
189
but dissimilar to the trauma or not distressing and dissimilar to the trauma. Results
indicated that more severe PTSD symptoms were reported by those experiencing
dreams highly similar to their traumatic experience at admission and follow-up.
Schreuder et al. (2000) conducted a larger study involving 167 civilian victims
and 56 combat veterans of World War II. Of those, 124 participants met full criteria
for PTSD and 102 reported posttraumatic nightmares. Posttraumatic nightmares
were categorized as “mostly or completely replicative” (42%; nightmares that were
very similar to the event), “mostly or completely nonreplicative” (28%; nightmares
that were an unrealistic account of the event), and “mixed replicative and nonreplicative” (35%; nightmares that were somewhat similar to the event) of the traumatic experience. Individuals reporting “mostly or completely replicative” nightmares also experienced more frequent nightmares, more repetitive nightmares, and
more symptoms of intrusion; however, they reported fewer psychological symptoms
as measured by the Symptom Checklist–90 (Derogatis, 1975; Derogatis et al., 1973).
The researchers suggested this may be due to the type of trauma experienced
because combat veterans made up a larger portion of the replicative posttraumatic
nightmare group and had lower overall Symptom Checklist–90 scores than those in
the other trauma groups. This finding raises interesting questions about the relationship between the content of nightmares and psychological symptomatology
other than PTSD.
Chronic nightmares, regardless of content, pose a significant problem for those
suffering from PTSD, but their effects may not be limited to individuals with PTSD
(e.g., Mellman et al., 1995). Recent evidence has suggested that chronic nightmares
may have negative consequences for trauma-exposed individuals without PTSD. In
the Schreuder et al. (2000) study, those with PTSD and nightmares, regardless of
content, reported more psychological symptoms. Persons with posttraumatic nightmares were also found to have worsened psychological and physical functioning
and increased sleep problems relative to those without such nightmares. Thus, it
appears that posttraumatic nightmares may be highly disruptive and affect multiple
areas of functioning, regardless of the presence of PTSD.
The present study extends current knowledge on chronic nightmare characteristics in a civilian sample by categorizing nightmares as replicative of, similar to,
or dissimilar to participant trauma experiences. Several hypotheses were formulated on the basis of past research. First, the prevalence of replicative nightmares
was expected to be lower than nightmares similar or dissimilar to trauma experiences. Second, replicative nightmares were expected to be associated with greater
distress (increased PTSD and depression symptoms, poorer sleep quality and
quantity, and greater frequency and severity of nightmares). Last, PTSD-positive
individuals were expected to report more frequent and severe nightmares and more
replicative nightmares than PTSD-negative individuals.
METHOD
Procedure
The present study is part of two larger studies evaluating the efficacy of a
cognitive– behavioral treatment for chronic nightmares in trauma-exposed persons.
190
Davis, Byrd, Rhudy, and Wright
Only baseline data from the two studies were used in this article. Participants were
recruited via flyers, e-mail, and radio ads from August 2002 through July 2006. The
ads stated that we were recruiting for a treatment study for recurring nightmares,
that treatment was free, and that participants would be compensated for the
evaluations. Potential participants were screened over the phone for trauma history, exclusion criteria, and frequency and duration of nightmares. Inclusion criteria
consisted of experiencing a traumatic event and having had nightmares at least once
per week for the previous 3 months. Exclusion criteria consisted of apparent
psychosis or mental retardation, age younger than 18, active suicidality or recent
parasuicidal behaviors, or current drug or alcohol dependence. There were no
restrictions on race or ethnic background. All participants who met inclusion
criteria were invited to participate in the study. Upper-level trained graduate
students conducted the assessments. Participants were provided a $20.00 gift certificate to a local department store to compensate them for their time.
Participants
A total of 94 people participated in the baseline evaluations, of which 49 (52%)
were in the first study and 45 (48%) were in the second study. Of the participants,
79% were women, 80% were Caucasian, and the mean age was 39.9 (SD ⫽ 11.99).
Thirty-seven percent of the sample were married, and 23% were divorced, and 71%
had at least some college education. The mean income of the sample was approximately $40,000 (SD ⫽ $54,043). Participants reported a mean of 4.6 different
traumatic events (SD ⫽ 2.02, range ⫽ 1–9). The most frequent types of trauma
reported were unwanted sexual contact (59.6%), car accident (58.5%), physical
assault with a weapon (54.3%), and physical assault without a weapon (51.1%).
Although having a PTSD diagnosis was not a requirement of the study, a total of
55% (n ⫽ 52) of the participants met criteria for current PTSD and 64% met
criteria for lifetime PTSD.
Measures
Demographic Questionnaire
The demographic questionnaire is a self-report measure designed to obtain
standard background information about the participants, including age, native
language, marital status, educational achievement, ethnicity, vocational status, and
household income.
Modified Trauma Assessment for Adults: Self-Report Version (TAA; Resnick,
Best, Kilpatrick, Freedy, & Falsetti, 1993)
The TAA assesses for lifetime history of 13 types of traumatic events, including
serious accidents, sexual assault, interpersonal traumas, natural disasters, witnessing a
violent crime, being diagnosed with a serious illness, having a friend or family
Characteristics of Chronic Nightmares
191
member deliberately killed, and other situations that involve fear of being killed or
seriously injured or in which injury took place. The TAA was modified to include
an additional five items assessing for hate crimes. Follow-up questions include age
of first and most recent occurrence for multiple incidents of a given type, physical
injury, and perceived life threat. The TAA’s validity is supported by consistent
findings with a different assessment measure of traumatic events. Furthermore,
comparison of TAA results with archival data from records in a mental health clinic
revealed that the TAA captured all reported and some unreported traumatic events
(Resnick, 1996).
Structured Clinical Interview for DSM–IV: PTSD Module (SCID; Spitzer,
Williams, & Gibbon, 1995)
The SCID is a formulized diagnostic interview developed to assess and closely
follow the criteria in the Diagnostic and Statistical Manual of Mental Disorders (4th
ed., or DSM–IV; American Psychiatric Association, 1994). The PTSD module
assesses current and lifetime diagnoses of PTSD. Researchers have found the SCID
to be a valid and reliable instrument in following diagnostic criteria set forth by the
DSM (e.g., Davidson, Smith, & Kudler, 1989). All participants in Study 1 were
administered the PTSD module of the SCID to determine current and lifetime
PTSD diagnosis.
Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995)
The CAPS is a semistructured interview that assesses lifetime and current
PTSD. It consists of 17 questions assessing the frequency and intensity of core
PTSD symptomatology. All participants in Study 2 were administered the CAPS to
determine current and lifetime PTSD diagnosis. Two methods for scoring criteria were
used as outlined by Weathers, Ruscio, and Keane (1999), which included the symptom
endorsement necessary to meet criteria according to the DSM–IV and the summing of
the frequency and intensity scores for each symptom while using the cut-off score of 65.
The symptom endorsement method has been shown to have a 91% sensitivity rate
and a 71% specificity rate, and the cut-off score of 65 has been shown to have 82%
sensitivity rate and a 91% specificity rate (Weathers et al., 1999). Blake et al. (1990)
reported interrater reliability ranging from .92 and .99 and perfect diagnostic
reliability using a sample of combat veterans. Weathers et al. conducted a test–
retest reliability investigation with 60 combat veterans and found interclass correlations of .93 for frequency scores and .95 for intensity scores. Furthermore, with a
sample of 243 veterans they also found internal consistency estimates using alpha of
.93 for frequency and .94 for intensity with all 17 items.
Beck Depression Inventory—II (BDI–II; Beck, Steer, & Brown, 1996)
The BDI–II is a 21-item self-report inventory to assess symptoms of depression. For each item, respondents assess symptom severity from four choices. Items
192
Davis, Byrd, Rhudy, and Wright
are added to yield a total score. This scale is a modified version of the BDI that has
been used in numerous research projects on depression (e.g., Beck, Steer, &
Garbin, 1988) and has also been used to assess depression in victims of crime
(Falsetti, Resnick, & Davis, 2005). The BDI–II has a reliability of .92.
Pittsburgh Sleep Quality Index (PSQI; Buysse, Reynolds, Monk, Berman,
& Kupfer, 1989)
The PSQI is a self-report measure designed to assess certain qualities and
problems associated with sleep. Participants rate quality of sleep and degree of
sleep difficulties for 1 month before the assessment. A global sleep quality score is
obtained by summing the seven component scores, including subjective sleep
quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances,
use of sleep medication, and daytime dysfunction. Higher scores reflect poorer
sleep quality. The global score may range from 0 to 21. The PSQI has acceptable
internal consistency, test–retest reliability, and validity (Buysse et al., 1989). Buysse
and colleagues determined a cut-off score of 5 as distinguishing “good” sleepers
from “poor” sleepers, with a diagnostic sensitivity of 89.6% and a specificity
of 86.5%.
Trauma Related Nightmare Survey (TRNS; Davis, Wright, & Borntrager, 2001)
The TRNS was developed to assess characteristics of chronic nightmares.
Likert-type, categorical, and open-ended questions assess the frequency, severity,
and duration of nightmares, as well as cognitions, emotions, and behaviors related
to nightmares. Participants were asked to indicate whether their nightmares were
“exactly or almost exactly like the trauma,” “similar to the trauma,” or “unrelated
to the trauma.” We allowed the participants to self-define their nightmares and
asked them to explain what they meant if they indicated that their nightmares were
trauma similar or trauma dissimilar. Examining their responses, trauma-similar
nightmares included aspects of the actual trauma, but the place, people, or specific
acts were different. Trauma-dissimilar nightmares included threatening or scary
situations but did not include any clear aspect of the traumatic event. Test–retest
analyses revealed adequate reliabilities for past-week hours of sleep per night (r ⫽
.72), fear of going to sleep (r ⫽ .77), depression upon waking (r ⫽ .72), feeling
rested upon waking (r ⫽ .65), frequency of nightmares (r ⫽ .64), and severity of
nightmares (r ⫽ .63; Byrd et al., 2006). Convergent validity was also found with
daily behavioral records of sleep and nightmares (Daily Sleep Activity Log;
Thompson, Hamilton, & West, 1995): nights with nightmares (rs ⫽ .74 –.82);
number of nightmares (rs ⫽ .76 –.81); and the Modified PTSD Symptom Scale
(MPSS) nightmare frequency (r ⫽ .64) and severity (r ⫽ .45; Byrd et al., 2006).
MPSS Self-Report (MPSS-SR; Resick, Falsetti, Resnick, & Kilpatrick, 1991)
The MPSS-SR is a modification of the PTSD Symptom Scale developed by
Foa, Riggs, Dancu, and Rothbaum (1993). Changes were made to assess for both
frequency and severity of PTSD symptoms. The scale consists of 17 items that
Characteristics of Chronic Nightmares
193
correspond to PTSD symptom criteria in the text revision of the DSM–IV (American Psychiatric Association, 2000). Frequency of PTSD symptoms is assessed on a
4-point scale ranging from 0 (not at all) to 3 (5 or more times per week/very
much/almost always). Severity of PTSD is assessed on a 5-point scale ranging from 0
(not at all distressing) to 4 (extremely distressing). The convergent validity of the
MPSS-SR with a structured clinical interview for PTSD (Spitzer et al., 1995)
revealed excellent results, with an overall hit rate of 97% when using the cut-offs
for the frequency scale (Wright, David, Inness, & Stem, 2003). The internal
consistency of the full scale MPSS-SR has been reported at levels of .96 and .97 in
treatment and community samples, respectively (Falsetti, Resick, Resnick, & Kilpatrick, 1992, as cited in Falsetti, Resnick, Resick, & Kilpatrick, 1993). The overall
frequency and severity subscales were used for the analyses. Symptoms were also
examined at the criterion level. For these analyses, the nightmare question was
removed from the reexperiencing category and the sleep difficulties question was
removed from the arousal category.
RESULTS
Participants reported a mean nightmare frequency of 4.01 nightmares per week
(SD ⫽ 3.78), 3.24 nights per week with nightmares (SD ⫽ 1.96), and 1.81 nights per
week with more than one nightmare (SD ⫽ 2.09). Average nightmare severity,
rated on a scale ranging from 0 (not at all disturbing) to 4 (extremely disturbing)
was 3.0 (SD ⫽ 0.78). Participants reported a mean of 5.65 (SD ⫽ 1.77) hour of sleep
per night, and 37% of the sample reported sleep initiation taking 1 or more hours
each night, on average.
The hypothesis that replicative nightmares would be less prevalent than trauma-similar or trauma-dissimilar nightmares was supported. Fifty percent reported
nightmares that were trauma similar, 29.5% reported nightmares that were trauma
dissimilar, and 20.5% reported nightmares that were replicative. One-way analyses
of variance were conducted on several measures of distress, with nightmare content
(replicative, trauma similar, trauma dissimilar) entered as the independent variable
(see Table 1). In support of the second hypothesis, individuals with replicative
nightmares reported fewer hours of sleep per night, greater fear of going to sleep,
greater depression upon waking, and poorer sleep quality than those with traumadissimilar nightmares. Individuals with replicative nightmares differed from those
with trauma-similar or trauma-dissimilar nightmares in terms of greater depression,
greater overall PTSD symptom frequency and severity, greater frequency and
severity of PTSD reexperiencing, and avoidance and arousal symptoms. Relative to
trauma-dissimilar nightmares, replicative and trauma-similar nightmares were associated with greater frequency of nightmares per week and more nights with
nightmares per week. Finally, people who reported trauma-similar nightmares
reported greater overall PTSD symptom frequency and severity and greater frequency and severity of reexperiencing and avoidance symptoms than those with
dissimilar nightmares.
Analyses of variance were conducted to compare characteristics of nightmares
and sleep problems by PTSD status (see Table 2). As hypothesized, results
indicated that PTSD-positive individuals reported greater frequency and severity of
194
Davis, Byrd, Rhudy, and Wright
Table 1. Type of Nightmare and Related Distress
Replicative
Trauma
similar
Trauma
dissimilar
Dependent variable
M
SD
M
SD
M
SD
F
df
No. hours slept per night
Fear of going to sleep
Depression upon waking
Feeling rested upon waking
Nightmares per week
Nights with nightmares per week
Nights with more than one nightmare
per past week
Disturbance of the nightmares
Global depression (BDI-II)
Overall sleep quality
Panic symptoms upon waking from
nightmare
Frequency of PTSD symptoms
Severity of PTSD symptoms
PTSD reexperiencing symptoms
PTSD avoidance symptoms
PTSD arousal symptoms
4.86a
2.00
2.39a
0.78
4.58
4.06a
1.63
1.14
0.92
0.88
2.54
2.60
5.73
1.43
1.75
1.23
4.59
3.51a
1.56
1.15
1.08
0.81
4.86
1.95
6.21b
1.23
1.38b
1.35
2.48
2.35b
1.97
1.11
1.10
0.94
1.10
1.02
3.35*
2.55
4.84*
2.51
2.78
5.02**
2, 85
2, 85
2, 85
2, 84
2, 83
2, 85
2.56a
3.33
31.67a
15.35a
2.28
0.69
11.33
3.86
2.06a
2.93
19.18b
13.38
2.24
0.82
10.32
4.23
0.76b
2.92
17.73b
11.08b
1.01
0.80
12.56
4.04
5.14**
1.89
9.77***
5.61**
2, 83
2, 85
2, 85
2, 81
5.89
40.59a
52.82a
22.82a
36.65a
21.59a
2.93
5.64
9.40
3.43
8.78
5.32
5.30
27.57b
32.25b
13.84b
23.50b
14.05b
2.98
11.97
16.35
7.69
11.55
7.67
4.00
16.35c
20.15c
8.12c
13.46c
10.08b
2.70
9.06
13.40
6.16
10.96
7.29
2.49
29.38***
26.53***
25.40***
23.33***
13.35***
2, 83
2, 84
2, 84
2, 84
2, 84
2, 84
Note. Specific type of sleep problems were rated on a Likert scale ranging from 0 (not at all) to 4
(extremely). Subscript letters indicate significant differences. BDI-II ⫽ Beck Depression Inventory—II;
PTSD ⫽ posttraumatic stress disorder.
* p ⬍ .05. ** p ⬍ .01. *** p ⬍ .001.
nightmares, poorer sleep quality and quantity, greater panic symptoms upon waking from nightmares, and greater global depression. The groups did not differ,
however, on reported severity of the nightmares. PTSD-positive individuals were
also more likely to report experiencing replicative nightmares and less likely to
report experiencing trauma-dissimilar nightmares than PTSD-negative individuals.
A series of regressions was conducted to determine whether nightmare severity or
frequency contributed to any sleep problems or related distress when controlling
for non–sleep-related PTSD symptoms. Results indicated that nightmare frequency
was a unique predictor of poor global sleep quality (B ⫽ 0.57, SE ⫽ 0.22),
t(86) ⫽ 2.58, p ⬍ .01, and fear of going to sleep (B ⫽ 0.13, SE ⫽ 0.06), t(90) ⫽ 2.34,
p ⬍ .02, whereas a trend existed regarding the role of the severity of the nightmare
in predicting panic symptoms on waking from a nightmare (B ⫽ 0.72, SE ⫽ 0.38),
t(88) ⫽ 1.89, p ⫽ .06.
DISCUSSION
The results of the present study indicate that approximately half of our civilian
sample reported experiencing nightmares that were similar in content to their
traumatic event, and 21% reported replicative nightmares. Previous studies have
found rates ranging from 40% (Schreuder et al., 2000) to 73% (van der Kolk et al.,
1984). It is difficult to compare the current findings with these studies because of the
different ways in which researchers have categorized nightmares (e.g., categorizing
trauma-similar and replicative nightmares together) and different trauma types
Characteristics of Chronic Nightmares
195
Table 2. Characteristics of Nightmares and Sleep Problems for Individuals Positive and Negative for
Posttraumatic Stress Disorder (PTSD)
Nightmare characteristics and
sleep problems
No. of hours slept per night
Fear of going to sleep
Depression upon waking
Feeling rested upon waking
Nightmares per week
Nights with nightmares per
week
Nights with more than one
nightmare per past week
Disturbance of the nightmares
Global depression (BDI-II)
Overall sleep quality
Panic symptoms upon waking
from nightmare
Replicative nightmare
Trauma
Similar nightmare
Dissimilar nightmare
PTSD positive
PTSD negative
M
SD
M
SD
F
df
5.13
1.71
2.17
0.92
4.74
1.52
1.13
0.94
0.88
4.17
6.33
1.08
1.08
1.51
3.07
1.87
1.12
1.07
0.72
3.00
11.53**
7.27**
27.19***
11.61**
4.44*
1, 90
1, 90
1, 90
1, 89
1, 88
3.82
2.08
2.50
1.55
11.19**
1, 90
2.30
3.12
25.81
14.63
2.23
0.78
10.98
4.13
1.13
2.85
14.39
11.00
1.70
0.77
10.79
3.78
7.30**
2.63
25.18***
18.38***
1, 88
1, 90
1, 91
1, 87
5.62
2.88
3.92
2.85
7.77**
1, 89
N
%
N
%
␹2
18.03***
17
32.69
1
2.77
27
8
51.92
15.38
17
18
47.22
50.00
2, 88
Note. Specific type of sleep problems were rated on a Likert scale ranging from 0 (not at all) to 4
(extremely). BDI-II ⫽ Beck Depression Inventory—II.
* p ⬍ .05. ** p ⬍ .01. *** p ⬍ .001.
(i.e., combat veterans may experience more replicative nightmares). The current
study suggests it may be important to distinguish trauma-similar nightmares from
replicative nightmares because differences were found on global depression, on
overall frequency and severity of PTSD symptoms, and for each PTSD criterion
category—reexperiencing, avoidance, and arousal. However, these results need to
be replicated before conclusions can be drawn.
A clear pattern emerged in the association between the degree of trauma
similarity of the nightmare and symptoms of PTSD. Individuals who reported
replicative nightmares also reported the greatest degree of distress. The present
study did not find, however, that other indices of distress were lower for individuals
with replicative nightmares, as did Schreuder et al. (2000). Indeed, replicative
nightmares were associated with greater distress in terms of fewer hours of sleep
per night, depression on waking, frequency of nights with nightmares, frequency of
nights with more than one nightmare, total number of sleep problems, and overall
sleep quality, in addition to the global depression and PTSD symptoms listed
above. We did not, however, include a general measure of psychopathology (i.e.,
Symptom Checklist-90), as did Schreuder and colleagues. It is important to note,
however, that trauma-similar and trauma-dissimilar nightmares were also associated with distress and sleep problems. This suggests that chronic nightmares have
a negative impact on individuals’ functioning, regardless of the similarity to trauma
experiences.
The findings from analyses comparing PTSD-positive and PTSD-negative
individuals were consistent with, and extended, previous work. Our findings re-
196
Davis, Byrd, Rhudy, and Wright
vealed that of the 18 people who reported replicative nightmares, only 1 did not
meet criteria for PTSD. Of those who met criteria for PTSD, 33% reported
replicative nightmares, with 52% reporting trauma-similar nightmares and 15%
reporting trauma-dissimilar nightmares. PTSD-positive individuals also reported
greater overall distress and lower sleep quality and quantity. Results indicated that
nightmares were associated with distress (global sleep quality and fear of going to
sleep) even after PTSD symptoms were controlled. This suggests that chronic
nightmares may be a major component of posttrauma response and may affect
some areas of functioning independent of PTSD. This may help to explain why
treatments that broadly target PTSD symptoms may not be successful at ameliorating nightmares (Forbes, Creamer, & Biddle, 2001; Schreuder, Igreja, van Dijk, &
Kleijn, 2001) compared with treatments that directly target nightmares (Davis &
Wright, 2007; Forbes et al., 2003; Krakow et al., 2001).
Future research is needed to determine whether the association between
nightmare content and distress severity is influenced by the length of time since the
most recent trauma or the trauma that initiated the nightmare. Empirical studies
have demonstrated that distress tends to be highest immediately after a trauma,
with gradual amelioration across time (Kessler, Sonnega, Bromet, Hughes, &
Nelson, 1995). Similarly, other studies have found that after a trauma, nightmares
tend to be replicative or very similar to traumatic events, but over time change
and distort (Hartmann, 1998). This brings into question the nature of this
association. Is nightmare content a predictor of long-term difficulties? Is degree
of trauma similarity of nightmare content a reflection of heightened distress or
a maintaining factor? Does this relationship change when nightmares do not
diminish, but remain a chronic problem? It will be important for future studies
to address these questions.
There are a few limitations of the present study to be considered. First, this was
a sample of trauma-exposed individuals seeking treatment for their nightmares.
These individuals likely represent an extreme end of the continuum of nightmare
sufferers, so it is unclear to what extent the present results generalize to other
trauma-exposed populations. The sample was also primarily composed of Caucasian women. Future studies will need to determine whether gender and ethnicity
contribute to differences in the experience of nightmares. Finally, information
distinguishing individuals who were lifelong nightmare sufferers versus individuals
whose nightmares began following a trauma was gathered only in the second study.
Previous research (e.g., van der Kolk et al., 1984) has suggested that this distinction
may be an important component in understanding the nature of chronic nightmares. We plan to examine these issues on completion of the current treatment
study.
In spite of these limitations, the present study lends support to results of
previous studies regarding the nature and characteristics of chronic nightmares in
trauma-exposed persons. Although additional research is warranted, it does appear
that all individuals with trauma, regardless of PTSD status, should be assessed for
their experience of nightmares. It remains unclear whether the differing symptom
levels by nightmare content suggest different considerations for or approaches to
treatment of the nightmares. Future treatment studies should assess whether nightmare content is related to treatment outcome.
Characteristics of Chronic Nightmares
197
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