Keywords
nightmare proneness - psychological distress - nightmares - chest pain - sleep fragmentation
Introduction
Nightmares, disturbing dreams that awaken the sleeper, are a relatively common sleep
disturbance. Approximately 4% of adults report frequent nightmares (that is, at least
weekly), while 40% report nightmares at least once a month.[1] The accepted etiologies of nightmares are not usually tied to specific, but rather
to more general, traits. For instance, it has been suggested that idiopathic nightmares
result from hyperarousal and general maladjustment[2] or indicate the presence of some form of psychopathology.[3] To better understand the specific aspects of maladjustment involved in nightmares,
the construct nightmare proneness (NP), a trait-like disposition to frequently experience
nightmares, was recently proposed.[4] Given its recent identification, little is known about the dynamics or characteristics
of NP.
In student samples, NP has been found to predict variance in nightmare frequency above
indices of psychopathology, including social anxiety, hypomanic traits, insomnia,[4] and posttraumatic stress symptomatology.[5] Nightmare proneness has been related to trait negative affect and its sibling, neuroticism,[5]
[6] which are putative risk factors for psychopathology.[7] However, NP also accounts for nightmares unrelated to negative affect or neuroticism.[5]
[6] Though NP has been related to both nightmares and maladjustment, why and how it
relates to these variables has not been well understood to date. One possible link
between NP and psychopathology is psychological distress.
Psychological distress (hereafter, distress) and NP have been strongly correlated
previously, and they share about half of their variance.[5]
[6] Given this, it is surprising that little attempt has been made to conceptually differentiate
the two. It has been suggested that NP might be a nightmare-specific form of maladjustment.[4] Indeed, the measure most used to operationalize NP, the Nightmare Proneness Scale,[4] was developed based on a longer measure of maladjustment. Nevertheless, stating
NP is a form of maladjustment provides limited benefit in distinguishing it from distress,
which can also be considered maladjustment.[7]
Distress has been conceptualized as including emotional arousal and discomfort, demoralization,
and suffering, typically in response to stressors.[8] Distress may result from the perceived inability to cope, and it has subsequent
effects on health, relationships, and self-image.[8] Similarly, NP has been theorized to include feelings of vulnerability,[5] which could reflect coping inefficacy. Also similar to distress, NP includes hyperarousal.[6] In terms of differences, NP, but not distress, appears to include general psychical
dysregulation.[4]
[6]
[8] Moreover, NP is hypothesized to include concretization: a process in which vague
feelings of discomfort are made concrete in the form of nightmarish images during
sleep states.[5]
Based on these conceptualizations, it seems possible that NP and distress overlap
with the shared empirical referents vulnerability and hyperarousal. However, other
elements such as concretization and general psychic dysregulation separate the two.
The fact that they tap two shared conceptual referents might partly account for their
high correlation. If concretization and general psychical dysregulation differentiate
NP and distress, the findings that NP predicts nightmares incremental of distress[5]
[6] would make theoretical sense.
One realm of variables in which NP and distress might be empirically distinguishable
are health behaviors and cardiac symptoms, that is, chest pain and irregular heartbeat.
In a large sample of adults,[9] distress was related to unhealthy behaviors, such as diet, smoking, and physical
inactivity. Similarly, Arbinaga et al.[10] found in a large student sample that both NP and nightmare frequency related to
insufficient physical activity. More broadly, Kelly and Yu[11] found that students with higher NP engaged in fewer cardio-related health behaviors
(such as healthy diet and exercise), yet distress and NP did not independently predict
health behaviors. While they did not examine cardiac symptoms, Kelly and Yu[11] proposed that NP might influence the relationship between nightmares and cardiac
symptoms noted in later life[12] through less engagement in cardiac health behaviors.
Previous research[13] found that cardiac symptoms reflect distress rather than cardiac disease among young
adults. Similarly, in community samples of young adults, psychotic experiences, which
might partly represent psychical dysregulation, predicted cardiac symptoms unrelated
to health behaviors and distress.[14] It has been proposed that the relationship between health complaints and maladjustment
reflects a general negative reporting bias rather than actual physical health conditions;
in other words, distressed individuals tend to express both poor mental and physical
health.[15] Another possibility is that, in healthy samples, specific physical symptoms such
as chest pain could indicate waking concretization. Asnes et al.[16] reported that among children cardiac symptoms are often psychogenic. While those
findings do not necessarily lead to the conclusion that chest pain is a concrete manifestation
of psychological states, the possibility remains. If this is the case, concretized
cardiac symptoms might distinguish NP and distress.
It is also possible that, even among healthy individuals, cardiac symptoms result
from other physiological and psychological processes. For instance, previous research
has indicated that sleep fragmentation, perhaps secondary to distress,[17] affects the cardiovascular system.[18] Additionally, the Type-D personality pattern, a combination of social inhibition
and negative affect,[19] has been related to cardiac symptoms among adults without apparent cardiovascular
disease.[20] Further, perceived difficulties coping with stressors have been related to cardiac
symptoms.[21]
The primary objective of the current study was to investigate if NP accounts for independent
variance in physical and psychological processes outside of distress; namely, potentially-concretized
cardiac symptoms, other conditions which might affect cardiac symptoms (sleep fragmentation,
Type-D personality, health behaviors, perceived stress), as well as overall perceptions
of physical health, nightmares, and general dream recall. A secondary aim was to extend
previous findings which related nightmares to cardiac symptoms in middle-aged and
older populations[12]
[22] while investigating other processes which might be involved. Given the previous
findings and conceptualizations of NP and distress, we expected that, outside of distress,
NP would independently account for independent variance among constructs that might
reflect concretization (cardiac symptoms) and nightmares. Further, we expected that
NP would account for cardiac symptoms unrelated to other possible influences, including
distress, sleep fragmentation, Type-D personality, and health behaviors.
Material and Methods
Participants
The study included 254 undergraduate students enrolled at a university in the Western
United States. [Table 1] displays the available demographics of the current sample.
Table 1
Self-reported demographics of the study sample.
|
Gender – n
|
Age in years
|
Ethnicity – %
|
Diagnosis of Cardiovascular Condition
|
|
Female – 175
|
Mean = 19.13
|
Latinx – 68%
|
No – 248
|
|
Male – 79
|
Standard deviation = ± 1.93
|
White/Caucasian – 12%
|
Yes – 6
|
|
Range = 18–37
|
Asian – 11%
|
|
|
Median = 19
|
African American – 6%
|
|
|
|
“Other” – 3%
|
|
Instruments
Nightmare Proneness
The 14-item Nightmare Proneness Scale[4] was used to assess NP. Its items assess a range of markers, but previous research
suggested the scale includes three factors: general psychical dysregulation, depressiveness,
and somatization.[6] The participants responses ranged from 1 (strongly disagree) to 7(strongly agree),
and they were added to generate a total NP score.
Distress
The four-item Patient Health Questionnaire-4[23] (PHQ-4) was used in the present study as a general marker of distress. The measure
assesses distress symptoms of depression and generalized anxiety. The participants
indicated how often they had been bothered by symptoms over the past 2 weeks using
a 4-point scale (from 0 = not at all to 3 = nearly every day). Though brief, the PHQ-4
has been found to have relatively equal psychometric qualities compared with a longer
version of the scale.[23]
Nightmares
Before completing the nightmare portion of the questionnaire, participants were informed
that nightmares are “disturbing, easily remembered dreams that awaken you from sleep,”
and were asked to respond accordingly. The 5-item SLEEP-50 Nightmare Scale[24] was used as a measure of general, nonspecific nightmares. Participants rated items
to describe nightmare experiences over the past four weeks. The rating scale ranged
from 1 (not at all) to 4 (very much). The three-item Posttraumatic Nightmare Index[25] assesses nightmare occurrences with content similar to traumatic experiences. The
rating scale ranges from 1 (strongly disagree) to 5 (strongly agree). A brief four-item
version of the Nightmare Distress Questionnaire[26] was developed for the present study by selecting the highest loading items from
Böckermann et al.'s[27] “General Nightmare Distress” factor. Though Böckermann et al.[27] initially assigned six items to the factor, two items regarding treatment seeking
were not included due to relatively low commonalities and cross-loadings on other
factors. The rating scale ranges from 1 (not at all) to 5 (very much).
Cardiac Symptoms
Cardiac symptoms were operationalized using two measures. First, the three-item WHO
Rose Angina Questionnaire-Short Form[28] assessed chest pain. Because of the brevity of the measure, the rating scale was
extended from the original yes/no format to scores ranging from 0 (never) to 4 (very
often) to increase sensitivity. Second, using the single-item scale from Asplund and
Aberg,[22] the participants indicated how often they were troubled by Irregular Heartbeat (0 = never,
4 = very often). To differentiate actual cardiac disease, the participants were asked
if they had been diagnosed with a cardiovascular condition by a physician. “Yes” responses
were coded as 1 and “no”, as 0.
Other Measures
The participants indicated their general Dream Recall Frequency over the past several
months using a single item from the Mannheim Dream (MADRE) questionnaire.[29] The response scores range from 0 (never) to 6 (almost every morning). The eight-item
Cardiac-Related Health Behaviors Index[30] was used to measure health behaviors (such as exercise and diet). The rating scale
range from 0 (never) to 4 (almost always). Higher scores indicated more healthy behaviors.
To assess general perceived physical health, the seven-item Physical Health Scale
of the Short-Form-12 Health Survey[31] was used. The responses were based on the past 4 weeks. Higher scores indicated
better perceived health. Perceived inability to cope with stressors over the past
month were assessed using the four-item version of the Perceived Stress Scale.[32] The response scores range from 0 (never) to 4 (very often). The Type-D Personality
pattern was assessed using the 14-item Type-D Personality Scale.[33] The Type-D scale includes two subscales: social inhibition and negative affect.
The rating scale ranges from 0 (false) to 4 (very true). Individuals were classified
as Type-D if they scored above 10 on both subscales.[33] Individuals classified as Type-D were coded as 1, and the others, as 0. Finally,
the nine-item Sleep Fragmentation Scale of the Iowa Sleep Disturbance Inventory[34] was used as a measure of difficulties in sleep maintenance. The participants responded
false/true.
Procedure
The present study was approved by the local research ethics review board. The participants
were recruited from the university's undergraduate psychology participants' pool to
complete a study on “Stress, Sleep, and Health.” Participation was voluntary, and
the undergraduates could choose from several studies in which to participate. After
electing to participate, the subjects were directed to an online survey system (Qualtrics),
provided written informed consent, and filled out the questionnaire. Data was collected
over a four-month period. A small amount of course credit was provided in exchange
for participation. There was no time limit to fill out the questionnaire and no exclusionary
criteria were used.
Statistical Approach
The analyses were conducted using the IBM SPSS Statistics for Windows (IBM Corp.,
Armonk, NY, US) software, version 28.0. Gender differences were examined using t-tests. Pearson correlations were used to examine relationships between NP and distress
and their relationships to other variables. To determine if NP and distress each reflect
unique individual variance, partial correlations were calculated for NP and distress
with all other variables while holding the other constant.[35]
To better understand the unique contributions of variables in predicting cardiac symptoms,
a linear regression was calculated. A composite cardiac symptoms measure (Rose angina + irregular
heartbeat; α = 0.62) was used as the criterion. In Step 1, gender and the cardiac
diagnosis were entered. In Step 2, dream recall, health behaviors, Type-D personality,
physical health perceptions, sleep fragmentation, perceived stress, general nightmares,
posttraumatic nightmares, and nightmare distress were entered. Distress was added
in Step 3, while NP was added in Step 4.
A second regression was calculated using NP as the criterion. Gender, cardiovascular
diagnosis, and dream recall were entered in Step 1. In Step 2, the nightmare variables
were entered (general nightmares, posttraumatic nightmares, and nightmare distress).
In Step 3, health and distress variables were entered (health behaviors, physical
health, sleep fragmentation, Type-D personality, perceived stress, and distress).
In Step 4, potentially-concretized physical experiences (Rose angina and irregular
heartbeat) were entered. The results were considered statistically significant if
p < 0.05 (two-tailed).
Results
Age only significantly correlated with health behaviors (r = 0.15; p = 0.020); older individuals reported more healthy behaviors. Gender differences were
observed (females scored higher than males) for NP (t [252] = 3.79; p < 0.001), nightmare distress (t [252] = 3.04; p = 0.001), sleep fragmentation (t [252] = 1.94; p = 0.027), psychological distress, (t [252] = 3.62; p < 0.001), and Type-D personality (t [252] = 2.08; p = 0.019).
Zero-order correlations are presented in [Table 2]. Consistent with previous research, NP and distress were strongly correlated, sharing
50% of their variance. In the present study, NP was significantly correlated with
all variables, except the frequency of dream recall. Similarly, distress significantly
correlated with all variables except dream recall and posttraumatic nightmares.
Table 2
Scale descriptives and Pearson correlations.
|
Variable
|
Nightmare Proneness
|
Psychological Distress
|
Mean (±Standard Deviation)
|
α
|
|
Nightmare proneness
|
|
|
47.49(±16.37)
|
0.88
|
|
Psychological distress
|
0.71***
|
|
03.86(±03.15)
|
0.85
|
|
General nightmares
|
0.25***
|
0.20***
|
10.15(±03.26)
|
0.74
|
|
Posttraumatic nightmares
|
0.22***
|
0.09
|
08.31(±03.43)
|
0.84
|
|
Nightmare distress
|
0.30***
|
0.25***
|
07.66(±03.45)
|
0.75
|
|
Dream recall frequency
|
0.10
|
0.11
|
03.35(±01.51)
|
–
|
|
Healthy behaviors
|
−0.21***
|
−0.18**
|
18.02(±05.57)
|
0.66
|
|
Chest pain
|
0.37***
|
0.22***
|
02.10(±01.86)
|
0.55
|
|
Irregular heartbeat
|
0.24***
|
0.19**
|
00.47(±00.86)
|
–
|
|
Sleep fragmentation
|
0.41***
|
0.27***
|
03.77(±02.60)
|
0.77
|
|
Physical health
|
−0.34***
|
−0.28***
|
26.36(±03.30)
|
0.70
|
|
Perceived stress
|
0.60***
|
0.67***
|
06.80(±02.83)
|
0.65
|
|
Type-D personality
|
0.52***
|
0.56***
|
00.54(±00.50)
|
0.89
|
Notes: N = 254; *p < 0.05; **p < 0.01; ***p < 0.001.
To better understand the characteristics of individuals who have higher nightmare
proneness, two groups were created and compared using t-tests – a nightmare prone group and a control group. Because no established system
has been developed to classify nightmare-prone individuals, a cut score of 64 (±1
standard deviation, SD) was used for the study sample. As such, 43 individuals were
placed in the nightmare-prone group and 211, in the control group. Results of t-tests
comparing the both groups are presented in [Table 3]. As seen in the table, nightmare-prone individuals can be described as more psychologically
distressed, recalling more dreams and nightmares, reporting nightmare distress, more
chest pain, sleep fragmentation, sensitivity to stressors, a Type-D personality, and
worse perceived physical health. These findings were generally consistent with the
correlations. The notable exception was that using categories rather than continuous
data, we found that nightmare-prone individuals recall more dreams. Further, there
was no significant difference between the groups in terms of healthy behaviors, though
a significant relationship was found with continuous data.
Table 3
Uncorrected t-tests comparing nightmare-prone individuals and controls.
|
Nightmare-0Prone
|
Control
|
|
|
|
|
Variable
|
Mean (±Standard Deviation)
|
Mean (±Standard Deviation)
|
t
|
p
|
d
|
|
Psychological distress
|
7.72 (±2.82)
|
3.08 (±2.58)
|
10.58
|
< .0001
|
1.77
|
|
General nightmares
|
11.65 (±3.34)
|
9.84 (±3.16)
|
3.39
|
< 0.001
|
0.57
|
|
Posttraumatic nightmares
|
9.51 (±3.38)
|
8.06 (±3.40)
|
2.55
|
0.011
|
0.43
|
|
Nightmare distress
|
8.81 (±3.67)
|
7.42 (±3.24)
|
2.51
|
0.013
|
0.42
|
|
Dream recall frequency
|
4.00 (±1.33)
|
3.22 (±1.52)
|
3.13
|
0.002
|
0.52
|
|
Healthy behaviors
|
17.02 (±4.77)
|
18.23 (±5.70)
|
1.30
|
0.197
|
0.22
|
|
Chest pain
|
3.42 (±2.41)
|
1.83 (±1.61)
|
5.37
|
< 0.001
|
0.90
|
|
Irregular heartbeat
|
0.81 (±1.12)
|
0.40 (±0.78)
|
2.93
|
0.004
|
0.49
|
|
Sleep fragmentation
|
5.60 (±2.27)
|
3.40 (±2.51)
|
5.34
|
< 0.001
|
0.89
|
|
Physical health
|
24.02 (±4.12)
|
26.83 (±2.90)
|
5.37
|
< 0.001
|
0.90
|
|
Perceived stress
|
9.47 (±2.38)
|
6.25 (±2.60)
|
7.48
|
< 0.001
|
1.25
|
|
Type-D personality
|
0.95 (±0.21)
|
0.46 (±0.50)
|
6.42
|
< 0.001
|
1.08
|
Note: N = 254.
Partial correlations for distress and NP while holding the other constant are presented
in [Table 4]. Nightmare proneness accounted for significant variance independent of distress
for all variables except dream recall and health behaviors. However, after accounting
for NP, distress only accounted for significant independent variance in perceived
stress and Type-D personality. The results did not appreciably change after also holding
constant cardiovascular diagnoses (results not presented).
Table 4
Partial correlations of nightmare proneness and psychological distress while holding
the other constant.
|
Variable
|
Partial r with Nightmare Proneness Holding Psychological Distress Constant
|
Partial r with Psychological Distress Holding Nightmare Proneness Constant
|
|
General nightmares
|
0.15*
|
0.04
|
|
Posttraumatic nightmares
|
0.22***
|
0.10
|
|
Nightmare distress
|
0.18**
|
0.05
|
|
Dream recall frequency
|
0.03
|
0.06
|
|
Healthy behaviors
|
−0.12
|
−0.04
|
|
Chest pain
|
0.32**
|
−0.07
|
|
Irregular heartbeat
|
0.14*
|
0.04
|
|
Sleep fragmentation
|
0.32***
|
−0.03
|
|
Physical health
|
−0.22***
|
−0.05
|
|
Perceived stress
|
0.24***
|
0.43***
|
|
Type-D personality
|
0.21***
|
0.31***
|
Notes: N = 254; *p < 0.05; ** p < 0.01; *** p < 0.001.
The regression predicting cardiac symptoms is presented in [Table 5]. Being diagnosed with a cardiac condition independently predicted cardiac symptoms
across all models. Similarly, perceived physical health and nightmare distress consistently
predicted cardiac symptoms. General experiences of nightmares predicted cardiac symptoms
until Step 4, when NP was added. Variables which would be expected to contribute to
cardiac disease, such as health behaviors and sleep fragmentation, contributed little
to cardiac symptoms in this sample of young adults. Distress, Type-D, and perceived
stress, which would indicate the influence of distress/psychopathology, also contributed
little independent variance to cardiac symptoms. Nightmare proneness contributed modestly,
but significantly, to the variance above all other measures. The latter finding supports
the contention that cardiac symptoms could represent concretization among healthy
young adults rather than negative-symptom reporting or psychopathology. When the regression
was recalculated without including cardiovascular diagnoses, the results did not change
appreciably. When recalculated using only chest pain as the criterion, the results
were similar, but cardiovascular diagnoses, nightmare distress, and general nightmares
did not predict chest pain in Step 2 or thereafter. Predicting only chest pain slightly
increased the strength of physical health and NP (results of the recalculated regressions
not presented).
Table 5
Regression models predicting cardiac symptoms.
|
Variable
|
Model 1
|
Model 2
|
Model 3
|
Model 4
|
|
β
|
t
|
p
|
Β
|
t
|
p
|
β
|
t
|
p
|
β
|
t
|
p
|
|
Gender
|
0.08
|
1.26
|
0.207
|
0.01
|
0.25
|
0.801
|
0.01
|
0.15
|
0.880
|
−0.01
|
0.23
|
0.816
|
|
Cardiac diagnosis
|
0.24
|
3.92
|
0.001
|
0.18
|
3.21
|
0.002
|
0.18
|
3.24
|
0.001
|
0.18
|
3.30
|
0.001
|
|
Dream recall frequency
|
|
|
|
0.02
|
0.42
|
0.672
|
0.02
|
00.39
|
0.695
|
0.03
|
0.44
|
0.660
|
|
Healthy behaviors
|
|
|
|
−0.05
|
0.90
|
0.368
|
−0.05
|
0.91
|
0.361
|
−0.04
|
0.75
|
0.452
|
|
Type-D personality
|
|
|
|
0.02
|
0.34
|
0.737
|
0.01
|
0.11
|
0.910
|
−0.03
|
0.40
|
0.690
|
|
Physical health
|
|
|
|
−0.21
|
3.34
|
0.001
|
−0.21
|
3.34
|
0.001
|
−0.19
|
3.14
|
0.002
|
|
Sleep fragmentation
|
|
|
|
0.06
|
0.95
|
0.341
|
0.05
|
0.87
|
0.386
|
0.01
|
0.07
|
0.946
|
|
Perceived stress
|
|
|
|
0.08
|
1.21
|
0.229
|
0.05
|
0.68
|
0.497
|
0.10
|
0.12
|
0.906
|
|
General nightmares
|
|
|
|
0.14
|
2.11
|
0.036
|
0.13
|
2.03
|
0.043
|
0.11
|
1.75
|
0.081
|
|
Posttraumatic nightmares
|
|
|
|
0.05
|
0.82
|
0.412
|
0.05
|
0.86
|
0.393
|
0.02
|
0.35
|
0.730
|
|
Nightmare distress
|
|
|
|
0.16
|
2.42
|
0.016
|
0.16
|
2.36
|
0.019
|
0.16
|
2.38
|
0.018
|
|
Psychological distress
|
|
|
|
|
|
|
0.06
|
0.68
|
0.497
|
−0.07
|
0.74
|
0.463
|
|
Nightmare proneness
|
|
|
|
|
|
|
|
|
|
0.28
|
3.21
|
0.001
|
|
⌂R2
= 0.06; F = 8.45; p < 0.001
|
⌂R2
= 0.21; F = 7.71; p < 0.001
|
⌂R2
= 0.01; F = 0.46; p < 0.497
|
⌂R2
= 0.03; F = 10.32; p < 0.001
|
The regression predicting NP is presented in [Table 6]. Gender predicted NP until sleep fragmentation and distress-related variables were
entered in Step 3. Similarly, nightmare distress and general nightmares predicted
NP until Step 3. It should be noted that posttraumatic nightmares predicted NP regardless
of distress. Sleep fragmentation and distress-related variables appeared to be strong,
consistent predictors of NP. Interestingly, chest pain, but not irregular heartbeat,
contributed modestly, but significantly, to the variance in NP above all other variables.
Table 6
Regression models predicting nightmare proneness.
|
Variable
|
Model 1
|
Model 2
|
Model 3
|
Model 4
|
|
β
|
t
|
p
|
β
|
t
|
p
|
β
|
T
|
p
|
β
|
t
|
p
|
|
Gender
|
0.23
|
3.67
|
0.001
|
0.20
|
3.28
|
0.001
|
0.08
|
1.88
|
0.061
|
0.07
|
1.79
|
0.075
|
|
Cardiac diagnosis
|
−0.01
|
0.07
|
0.943
|
−0.03
|
0.51
|
0.613
|
0.01
|
0.02
|
0.981
|
−0.01
|
0.32
|
0.749
|
|
Dream recall frequency
|
0.09
|
1.38
|
0.168
|
0.01
|
0.16
|
0.871
|
−0.01
|
−0.20
|
0.843
|
−0.01
|
0.26
|
0.797
|
|
Nightmare distress
|
|
|
|
0.15
|
2.12
|
0.035
|
0.00
|
0.09
|
0.932
|
−0.02
|
0.30
|
0.761
|
|
Posttraumatic nightmares
|
|
|
|
0.14
|
2.24
|
0.026
|
0.11
|
2.53
|
0.012
|
0.10
|
2.27
|
0.024
|
|
General nightmares
|
|
|
|
0.15
|
2.19
|
0.030
|
0.07
|
1.51
|
0.133
|
0.06
|
1.19
|
0.234
|
|
Healthy behaviors
|
|
|
|
|
|
|
−0.04
|
−0.86
|
0.391
|
−0.03
|
0.68
|
0.498
|
|
Sleep fragmentation
|
|
|
|
|
|
|
0.17
|
3.94
|
0.001
|
0.17
|
3.86
|
0.001
|
|
Physical health
|
|
|
|
|
|
|
−0.06
|
1.21
|
0.227
|
−0.02
|
0.35
|
0.725
|
|
Psychological distress
|
|
|
|
|
|
|
0.43
|
7.27
|
0.001
|
0.42
|
7.31
|
0.001
|
|
Perceived stress
|
|
|
|
|
|
|
0.16
|
2.77
|
0.006
|
0.15
|
2.72
|
0.007
|
|
Type-D personality
|
|
|
|
|
|
|
0.13
|
2.52
|
0.013
|
0.13
|
2.56
|
0.011
|
|
Rose angina
|
|
|
|
|
|
|
|
|
|
0.15
|
3.24
|
0.001
|
|
Irregular heartbeat
|
|
|
|
|
|
|
|
|
|
0.00
|
0.08
|
0.938
|
|
⌂R2
= 0.06; F = 5.42; p = 0.001
|
⌂R2
= 0.10; F = 9.42; p < 0.001
|
⌂R2
= 0.47; F = 49.73; p < 0.001
|
⌂R2
= 0.02; F = 5.83; p = 0.003
|
Discussion
The results of the present study suggest that NP has several characteristics which
identify it as a construct separate from distress. These findings characterize individuals
with NP as more likely to experience distressing nightmares, particularly posttraumatic
nightmares, having fragmented sleep, feeling overwhelmed with stressful situations,
experiencing more depressive and anxious distress, having a combination of social
inhibition and negative affect, and reporting more experiences of chest pain. These
findings were consistent with those of previous research that found NP related to
insomnia, social anxiety,[4] posttraumatic stress symptoms, and psychological distress,[5] as well as theoretical speculations that NP includes heightened vulnerability to
stressors, hyperarousal, psychical dysregulation, and concretization.[5] The current results also were in accordance with the aforementioned conceptualizations
of NP and distress.
If NP is a form a maladjustment,[4] it is a form that appears independent of distress, several risk factors for psychopathology,
and perhaps a negative reporting bias. Similarly, but inconsistent with previous assertions,[13]
[15] chest pain among healthy young adults did not appear solely to be a manifestation
of distress or a general reporting bias. Yet, it did appear partly to reflect perceptions
of poor physical health. This could indicate an overconcern with, or sensitivity to,
somatic processes.[36] The current data did not allow for this distinction or possible mechanisms, though
it appears to occur independent of maladjustment.
Given its independent relations with NP outside of physical health perceptions and
distress, chest pain could represent a concrete manifestation of psychological states
among relatively healthy young adults. This is consistent with findings that chest
pain among children is psychogenic, linked to real or imagined stressful experiences.[16] However, considering its lack of independent relationships with NP, irregular heartbeat
might be more a manifestation of distress rather than concretization.[37] Whether or not chest pain among young adults is considered concretization, findings
that cardiac symptoms were related to nightmares among large community samples of
middle-aged[22] and older[12] adults should be revisited examining possible effects of distress and NP.
To the extent that chest pain in healthy individuals indicates concretization, the
current findings support theoretical assertions that NP partly includes concrete manifestations
of vague, uncomfortable psychological states.[5] The findings that chest pain predicted NP independent of cardiovascular diagnoses,
sleep fragmentation (which increases sensitivity to actual physical pain[38]), as well as distress-related variables, which have been related to chest pain,[13]
[20] lends some credence to the tentative conceptualization of chest pain as concretization
among healthy young adults. However, it remains possible that chest pain in young
adults could instead result from hyperventilation secondary to hyperarousal or other
mechanisms.[37]
The present study extended knowledge of NP relative to other psychological and physical
processes in several ways. For instance, NP was related not only to general nightmare
frequency and nightmare distress,[5] but also to posttraumatic nightmares. Indeed, posttraumatic nightmares were more
strongly related to NP than nonspecific nightmares. Also, it was found that NP was
more strongly related to physical health perceptions and cardiac symptoms than it
was to health-related behaviors. Given the current results, speculations that NP affects
cardiovascular disease later in life through health behaviors[11] seems unlikely.
Further, the current findings suggest it is unlikely that individuals with higher
NP report more nightmares as a result of dream recall. This adds to previous findings
that NP was independent from typical sleep duration.[5] Together, these findings mitigate an explanation that NP individuals report more
nightmares as a result of having access to longer sleep episodes or recalling more
vivid, emotional dreams. It might also suggest that dreams and nightmares are somewhat
disparate, though likely related, processes influenced by somewhat different mechanisms.
Nevertheless, it is possible that individuals with NP have more nightmares due to
a greater proportion of REM sleep,[39] or that fragmentation of sleep might enable a greater recall of bad dreams.[40]
Additional systematic investigations are needed to better understand the origins and
mechanisms of NP and why it is strongly related to distress but remains statistically
separate. It has been speculated that NP results from weakened psychic structures.[5] The notion of weakened psychic structures among individuals with NP is consistent
with previous findings that “thin” psychological boundaries independently predicted
NP apart from neuroticism and nightmare frequency.[41] Thin boundaries suggest an incohesive and dysregulated mental organization leaving
individuals feeling dysregulated and vulnerable to distress.[42]
[43]
Another possible origin of NP and its link with distress is high sensory sensitivity.
A recent study[44] found that sensory sensitivity, heightened responsiveness to stimuli, and emotional
processing were related to nightmare frequency and distress. It is possible that individuals
with high NP and those who experience distress are more responsive to internal and
external stimuli and easily overwhelmed by stress, both of which could indicate thin
boundaries as well. Moreover, the responsiveness and overwhelmedness of highly-sensitive
individuals correspond to Kelly and Yu's[5] notion of a weakened psychic structure and corresponding sensitivity and vulnerability
which underly NP.
The current study had several limitations which should be considered before generalizing
the results. For instance, the reliance on a relatively homogenous student sample
makes extending the results to other populations difficult. Indeed, the sample mostly
consisted of young Latinx females, which might have biased the results. The use of
retrospective self-report measures without controlling for social desirability or
other biases is problematic. Underlying, undiagnosed cardiovascular syndromes in the
current study may have influenced the results. While this seems unlikely given the
nature of the sample, it should be considered in future research. It is regrettable
that, aside from a few demographic variables, the background of the current sample,
which involves trauma history and medications, was not thoroughly examined. This provides
less context to understand the results. Given the limitations of the current study,
its findings should be considered tentative.
Additional research is needed to account for the limitations of the current study
and to clarify its results. For instance, it would be helpful to understand how background
factors such as the use of medications, previous psychiatric treatment, socioeconomic
status, and family history might influence relationships regarding NP, distress, nightmares,
and cardiac symptoms. Also, additional research is needed to better understand the
relationship between NP and nightmares themselves. Outside speculations of concretization,
the mechanisms of this relationship are not known. It is possible that individuals
with NP have more nightmares due to increased amounts of REM and/or fragmented sleep,
giving NP individuals more “access” to nightmares. Also, research could examine how
thin boundaries and sensory sensitivity might influence NP and connect it with nightmares
and distress. Importantly, to understand the implications of the current results,
additional study is needed to establish if chest pain represents concretized inner
states among healthy samples or other mechanisms such as hyperventilation related
to hyperarousal. Finally, additional studies using a more diverse community and clinical
samples would be of interest.
