Reactivity to interoceptive cues in nocturnal panic

Interoceptive accuracy correlates with precision of time perception in the millisecond range

It has been proposed that accuracy in time perception is related to interoceptive accuracy and vagal activity. However, studies investigating time perception in the supra-second range have provided mixed results, and few studies have investigated the sub-second range. Moreover, there is a lack of studies investigating the relationship between precision in time perception and interoceptive accuracy. A recent meta-analytic review of neuroimaging studies proposed a dynamic interaction between two types of timing processing-an endogenous time keeping mechanism and the use of exogenous temporal cues. Interoceptive accuracy may affect both accuracy and precision of primary temporal representations, as they are generated based on the endogenous time keeping mechanism. Temporal accuracy may vary when adapted to the environmental context. In contrast, temporal precision contains some constant noise, which may maintain the relationship with interoceptive accuracy. Based on these assumptions, we hypothesized that interoceptive accuracy would be associated with temporal precision in the sub-second range, while vagal activity would be associated with temporal accuracy. We used the temporal generalization task, which allowed us to calculate the indices of temporal accuracy and temporal precision in line with the existing research, and also compute the index of participants' sensitivity according to the signal detection theory. Specifically, we investigated whether (1) interoceptive accuracy would correlate with temporal accuracy, temporal precision, or sensitivity and (2) resting-state vagal activity would correlate with temporal accuracy, temporal precision, or sensitivity. The results indicated that interoceptive accuracy was positively correlated with temporal precision as well as sensitivity, but not with temporal accuracy, in the sub-second range time perception. Vagal activity was negatively correlated only with sensitivity. Furthermore, we found a moderation effect of sensitivity on the relationship between vagal activity and perceived duration, which affected the association between vagal activity and temporal accuracy. These findings suggest the importance of precision as an aspect of time perception, which future studies should further explore in relation to interoception and vagal activity, and of the moderation effects of factors such as participants' sensitivity in this context.

Comparing symptom networks of daytime and nocturnal panic attacks in a community-based sample

Nocturnal panic refers to waking in a state of panic without obvious triggers, experiencing the same symptoms as panic attacks that occur while awake. Interrelationships between daytime and nocturnal panic symptoms have not been examined despite theories suggesting panic symptoms perpetuate one another in a forward feedback loop. The current study compared associations between symptoms in daytime and nocturnal panic using network analysis. Network theory conceptualizes symptoms as causing one another, rather than originating from a latent variable (i.e., a disorder). Given that nocturnal panic originates from sleep stages without cognitive activity, cognitive symptoms were expected to be more central in daytime panic networks than nocturnal panic networks. Prior literature indicates similar nocturnal and daytime panic severity; thus, we expected that panic groups would report equivalent panic symptom severity. An online community sample (N = 215) provided panic symptom history. Panic network structures did not differ, although the daytime panic network produced stronger and more numerous connections between physical and cognitive symptoms. The nocturnal panic group, however, reported more severe cognitive symptoms than the daytime panic group. These results challenge biologically-focused nocturnal panic theories and suggest a more significant role of cognitive symptoms in perpetuating nocturnal panic attacks once the individual awakens.

Expanding Fear of Loss of Vigilance: Intolerance of Uncertainty, Responsibility for Harm, and Fear of Sleep for Predicting Nocturnal Panic

OBJECTIVE/BACKGROUND

Nocturnal panic involves experiencing panic attacks out of a sleeping state without obvious causes. Roughly half of patients with panic disorder will experience nocturnal panic in addition to panic attacks while awake, or daytime panic. Like daytime panic, nocturnal panic also occurs in other disorders such as PTSD. The Fear of Loss of Vigilance theory is currently the only model available to explain nocturnal panic. It suggests nocturnal panickers fear states in which they cannot easily react to or protect themselves from danger. The current study sought to expand upon the existing theory by including constructs from the broader anxiety literature. Nocturnal panickers were expected to report higher scores on these measures when compared to daytime panickers and non-panickers.

PARTICIPANTS

A sample of 166 participants were screened for panic history.

METHODS

Participants completed self-report measures regarding panic attacks, fear of sleep, intolerance of uncertainty, responsibility for harm, and fear of loss of vigilance.

RESULTS

Measures of fear of sleep and responsibility for harm successfully differentiated nocturnal from daytime panickers, whereas measures of intolerance of uncertainty and fear of loss of vigilance did not.

CONCLUSIONS

These results provide partial support for the Fear of Loss of Vigilance theory. Modifications to the theory to incorporate additional constructs are suggested.

Time is body: Multimodal evidence of crosstalk between interoception and time estimation

Theoretical approaches propose a blending between interoception and time estimation. Interoception might constitute a neurophysiological mechanism for encoding duration. However, no study has assessed the convergence between interoception and time estimation using behavioral, neurophysiological, and functional anatomy signatures. We examined the multimodal convergence between interoception and time estimation using a two-fold approach. In study 1, we developed a dual design combining interoception (measuring heartbeat detection - HBD, and heartbeat evoked potential - HEP) with a time estimation paradigm (TEP, estimation of duration of a 120 s interval). In study 2, we performed a conjoint metanalysis (Multi-level Kernel Density Analysis, MKDA) of neuroimaging, including reports of interoception and time estimation. Both studies provide convergent evidence of time estimation's significant involvement in behavioral, electrophysiological (enhanced HEP), and neuroimaging (overlapping cluster in the right insula and operculum) signatures of interoception. Convergent results from both studies offer direct support for a shared mechanism of interoception and time estimation.

The association between nocturnal panic attacks and suicidal ideation, plans, and attempts

Panic and sleep disturbances are established risk factors for suicide. Nocturnal panic attacks, which occur out of sleep, represent an intersection of these risk factors. Only one study to date has examined this relationship, but measured suicidality as a unitary construct. This represents a significant gap in the literature, considering most individuals who think about suicide do not make a plan and most who make a plan never make an attempt. We sought to expand upon existing research by examining how nocturnal panic relates to suicidal ideation, plans, and attempts separately. We predicted nocturnal panic would be associated with more suicidal ideation, plan, and attempt history than daytime only panic and no panic. Participants recruited from an online community sample were thoroughly screened for nocturnal and daytime panic history and completed questionnaires about past suicidal ideation, plans, and attempts. Nocturnal and daytime panic groups did not differ in past suicidal ideation or plans, but both groups exceeded the non-panic group. The nocturnal panic group reported more suicide attempts than the daytime and non-panic groups and judged themselves as more likely to make an attempt in the future. These results indicate a promising avenue for future research and suicide prevention efforts.

Do interoceptive accuracy and interoceptive sensibility predict emotion regulation?

INTRODUCTION

Interoception refers to awareness, interpretation, and integration of sensations in the body. While interoceptive accuracy has long been regarded as a core component of emotional experience, less is known about the relationship of interoceptive accuracy and related facets of interoception to emotion regulation deficits. This study explores how interoceptive accuracy and interoceptive sensibility relate to emotion regulation in a non-clinical sample.

METHODS

Undergraduate participants completed a heartbeat perception task and the Multidimensional Assessment of Interoceptive Awareness (Noticing and Body Listening sub-scales), and rated their confidence in performance on the heartbeat perception task. Participants also completed self-report measures of emotional awareness and regulation (Profile of Emotional Competence, intrapersonal emotion identification and emotion regulation sub-scales), and rated their use of different coping strategies (Brief COPE).

RESULTS

Noticing predicted emotion identification, emotion regulation, and the use of adaptive but not maladaptive coping strategies. Heartbeat perception accuracy did not significantly contribute to the prediction of any outcome variables.

DISCUSSION

Future work is needed to extend these findings to clinical populations. The results from this study support the use of interoceptive training interventions to promote emotional wellbeing.

Sleep disturbance in PTSD and other anxiety-related disorders: an updated review of clinical features, physiological characteristics, and psychological and neurobiological mechanisms

The current report provides an updated review of sleep disturbance in posttraumatic stress disorder and anxiety-related disorders. First, this review provides a summary description of the unique and overlapping clinical characteristics and physiological features of sleep disturbance in specific DSM anxiety-related disorders. Second, this review presents evidence of a bidirectional relationship between sleep disturbance and anxiety-related disorders, and provides a model to explain this relationship by integrating research on psychological and neurocognitive processes with a current understanding of neurobiological pathways. A heuristic neurobiological framework for understanding the bidirectional relationship between abnormalities in sleep and anxiety-related brain pathways is presented. Directions for future research are suggested.

Delivering Cognitive Behavioral Therapy for Insomnia in the Real World: Considerations and Controversies

Cognitive-behavioral therapy for insomnia (CBT-I) has emerged as the first-line treatment for chronic insomnia but remains massively underused relative to the prevalence of insomnia disorder. This article focuses on 3 key issues in the delivery of CBT-I in the real world. First, where and how should CBT-I be delivered and who should deliver it? Second, who is an appropriate candidate for CBT-I? Third, how do you measure quality care with CBT-I? These issues give rise to targets for future research aimed at improving the implementation science of CBT-I in the real world.

Intolerance of uncertainty and responsibility for harm predict nocturnal panic attacks

Nocturnal panic involves waking suddenly from sleep in a state of panic, with no apparent cause, and affects more than half of patients with panic disorder. The Fear of Loss of Vigilance theory is the only proposed model for nocturnal panic, suggesting nocturnal panickers fear states in which they are unable to react to danger or protect themselves from threats. Prior work using a self-report questionnaire designed to test the theory (i.e., Fear of Loss of Vigilance Questionnaire; FLOVQ) was unsuccessful at differentiating nocturnal from daytime panickers. This study tested the theory using alternative measures to the FLOVQ. We predicted nocturnal panickers would show elevated responses to measures assessing fears of being unable to respond to or protect themselves from threats. A diverse community sample (N = 218) completed self-report measures related to panic attacks, intolerance of uncertainty, responsibility for harm, and anxiety sensitivity dimensions. Nocturnal panickers endorsed greater inhibitory intolerance of uncertainty and responsibility for harm, but not prospective intolerance of uncertainty, or anxiety sensitivity physical or cognitive concerns. This study provides support for the fear of loss of vigilance theory and suggests intolerance of uncertainty and responsibility for harm reduction be targeted in treatment for nocturnal panic attacks.

Panic and comorbid depression and their associations with stress reactivity, interoceptive awareness and interoceptive accuracy of various bioparameters

BACKGROUND

While current theories on perception of interoceptive signals suggest impaired interoceptive processing in psychiatric disorders such as panic disorder or depression, heart-rate (HR) interoceptive accuracy (IAc) of panic patients under resting conditions is superior to that of healthy controls. Thus, in this study, we chose to assess further physiological parameters and comorbid depression in order to get information on how these potentially conflicting findings are linked together.

DESIGN

We used a quasi-experimental laboratory design which included multi-parametric physiological data collection of 40 panic subjects and 53 matched no-panic controls, as well as experimental induction of stress and relaxation over a time-course.

METHODS

Stress reactivity, interoceptive awareness (IAw; from the Body Perception Questionnaire (BPQ)) and IAc (as correlation between self-estimation and physiological data) were major outcome variables. Self-estimation of bioparametrical change was measured via numeric rating scales.

RESULT

Panic subjects had stronger HR-reaction and more accurate HR-interoception. Concurrently, though, their IAc of skin conductance level, pulse amplitude and breathing amplitude was significantly lower than that of the control group. Interestingly, comorbid depression was found to be associated with increased IAw but attenuated IAc.

LIMITATIONS

Demand characteristics and a categorical approach to panic confine the results.

CONCLUSION

The potentially conflicting findings coalesce, as panic was associated with an increase of the ability to perceive the fear-related parameter and a simultaneous decrease of the ability to perceive other parameters. The superordinate integration of afferent signals might be impaired.

Neuroanatomical substrates for the volitional regulation of heart rate

The control of physiological arousal can assist in the regulation of emotional state. A subset cortical and subcortical brain regions are implicated in autonomic control of bodily arousal during emotional behaviors. Here, we combined human functional neuroimaging with autonomic monitoring to identify neural mechanisms that support the volitional regulation of heart rate, a process that may be assisted by visual feedback. During functional magnetic resonance imaging (fMRI), 15 healthy adults performed an experimental task in which they were prompted voluntarily to increase or decrease cardiovascular arousal (heart rate) during true, false, or absent visual feedback. Participants achieved appropriate changes in heart rate, without significant modulation of respiratory rate, and were overall not influenced by the presence of visual feedback. Increased activity in right amygdala, striatum and brainstem occurred when participants attempted to increase heart rate. In contrast, activation of ventrolateral prefrontal and parietal cortices occurred when attempting to decrease heart rate. Biofeedback enhanced activity within occipito-temporal cortices, but there was no significant interaction with task conditions. Activity in regions including pregenual anterior cingulate and ventral striatum reflected the magnitude of successful task performance, which was negatively related to subclinical anxiety symptoms. Measured changes in respiration correlated with posterior insula activation and heart rate, at a more lenient threshold, change correlated with insula, caudate, and midbrain activity. Our findings highlight a set of brain regions, notably ventrolateral prefrontal cortex, supporting volitional control of cardiovascular arousal. These data are relevant to understanding neural substrates supporting interaction between intentional and interoceptive states related to anxiety, with implications for biofeedback interventions, e.g., real-time fMRI, that target emotional regulation.

Predicting rapid response to cognitive-behavioural treatment for panic disorder: the role of hippocampus, insula, and dorsolateral prefrontal cortex

Although cognitive-behavioural therapy (CBT) is an effective first-line intervention for anxiety disorders, treatments remain long and cost-intensive, difficult to access, and a subgroup of patients fails to show any benefits at all. This study aimed to identify functional and structural brain markers that predict a rapid response to CBT. Such knowledge will be important to establish the mechanisms underlying successful treatment and to develop more effective, shorter interventions. Fourteen unmedicated patients with panic disorder underwent 3 T functional and structural magnetic resonance imaging (MRI) before receiving four sessions of exposure-based CBT. Symptom severity was measured before and after treatment. During functional MRI, patients performed an emotion regulation task, either viewing negative images naturally, or intentionally down-regulating negative affect by using previously taught strategies of cognitive reappraisal. Structural MRI images were analysed including left and right segmentation and volume estimation. Improved response to brief CBT was predicted by increased pre-treatment activation in bilateral insula and left dorsolateral prefrontal cortex (dlPFC) during threat processing, as well as increased right hippocampal gray matter volume. Previous work links these regions to improved threat processing and fear memory activation, suggesting that the activation of such mechanisms is crucial for exposure-based CBT to be effective.

Efficacy of Two Cognitive-Behavioral Treatment Modalities for Panic Disorder With Nocturnal Panic Attacks

The aim of this research was to examine the efficacy of two cognitive-behavioral treatment modalities for panic disorder (PD) with nocturnal panic (NP). The first study was conducted to determine whether conventional CBT for PD was effective for PD with NP in three participants. A second study sought to explore whether a CBT adapted to NP would lead to different clinical outcomes in three other participants. A multiple-baseline single-case design across individuals was used in both studies. Treatment outcome was assessed with standardized clinician ratings, self-report questionnaires, and daily self-monitoring. Results revealed that both the conventional and the adapted treatments showed a faster decrease in NPs versus daytime panics and significant clinical changes in all measures for up to a year after therapy. Hence, the changes brought about by the adapted treatment seemed to be similar to those obtained using conventional treatment. In light of these results, it can be presumed that conventional strategies may be sufficient for the treatment of NP. These observations raise questions regarding the real need to adapt treatments specifically to NP.

A transdiagnostic approach to treating sleep disturbance in psychiatric disorders

Sleep disturbance commonly co-occurs with a range of psychiatric disorders. This is of concern given the accruing evidence that sleep is critically important for mood regulation, physical health, cognitive functioning, and quality of life. There is strong evidence that insomnia, even if it is comorbid with another psychiatric disorder, is treatable with cognitive behavioral therapy. There is a need to develop cognitive behavioral approaches to the other types of sleep disturbance often experienced by patients with psychiatric disorders, such as hypersomnia, reduced sleep need, delayed phase, nocturnal panic attacks, and nightmares. The possibility of developing a transdiagnostic treatment that comprehensively treats sleep disturbance for use across psychiatric disorders is discussed because (a) there are many disorders in which multiple types of sleep disturbance can be characteristic at one time or over the life-course of the disorder and (b) there are considerable challenges inherent to disseminating any new treatments but particularly many "disorder-specific" treatments.

Anxiety and its treatment: promoting science-based practice

In this article we analyze ways that psychological science can inform the treatment of anxiety disorders. We focus on experimental psychopathology research to describe the structure of anxiety and the functions of danger, safety, predictability and controllability in contributing to disorder. We then address science-based practice in terms of principles of change and the benefits from the self-corrective nature of science, contrasting this form of practice with treatments that are not grounded in basic learning theory. Models for dissemination and implementation of science-based practices are described and related to practitioner attitudes regarding scientific evidence. Finally, we consider practice implications when treatments are, and are not, based on the informative role of clinical psychological science.

Biological sex and panic-relevant anxious reactivity to abrupt increases in bodily arousal as a function of biological challenge intensity

An emerging pattern of results from panic-relevant biological challenge studies suggests women respond with greater subjective anxiety than men, but only to relatively abrupt and intense challenge procedures. The current investigation examined the relation between biological sex and self-reported anxious reactivity following biological challenges of varying durations and intensity. Participants were 285 (152 females; M(age) = 21.38; SD = 5.92) nonclinical adults who completed one of three protocols: a 3-min voluntary hyperventilation challenge (VH), a 5-min 10% carbon dioxide-enriched air (CO(2)) challenge, or a 25-s 20% CO(2) challenge. As predicted, results indicated that the 20% CO(2) challenge elicited greater self-reported anxiety than the VH and 10% CO(2) challenges. Moreover, women endorsed greater anxious reactivity than men, but only following the 20% CO(2) challenge. Results are discussed in terms of processes likely to account for sex differences in anxious reactivity following relatively abrupt and intense biological challenges.

Sleep in psychiatric disorders: where are we now?

Although the precise function of sleep is unknown, decades of research strongly implicate that sleep has a vital role in central nervous system (CNS) restoration, memory consolidation, and affect regulation. Slow-wave sleep (SWS) and rapid eye movement (REM) sleep have been of significant interest to psychiatrists; SWS because of its putative role in CNS energy recuperation and cognitive function, and REM sleep because of its suggested involvement in memory, mood regulation, and possible emotional adaptation. With the advent of the polysomnogram, researchers are now beginning to understand some of the consequences of disrupted sleep and sleep deprivation in psychiatric disorders. The same neurochemistry that controls the sleep-wake cycle has also been implicated in the pathophysiology of numerous psychiatric disorders. Thus it is no surprise that several psychiatric disorders have prominent sleep symptoms. This review will summarize normal sleep architecture, and then examine sleep abnormalities and comorbid sleep disorders seen in schizophrenia, as well as anxiety, cognitive, and substance abuse disorders.

Subtypes of panic attacks: a critical review of the empirical literature

BACKGROUND

Panic disorder is a heterogeneous disorder, comprising a variety of somatic, physiological, and cognitive symptoms during repeated panic attacks. As a result, considerable data have examined whether panic attacks may be classified into distinct diagnostic or functional subtypes. The aim of this study is to evaluate the existing literature regarding the validity of panic attack subtypes.

METHODS

This review focuses on data published since 2000, with the publication of DSM-IV-TR, augmented by replicated data published since 1980, with the publication of DSM-III and subsequently DSM-IV. Published reports evaluating empirical evidence for the validity of panic attack subtypes are reviewed.

RESULTS

Five sets of panic symptoms (respiratory, nocturnal, nonfearful, cognitive, and vestibular) have been shown to cluster together at varying degrees of consistency. However, none of these potential subtypes have been associated with sufficient and reliable external validation criteria indicative of functional differences. This apparent lack of findings may be related to methodological inconsistencies or limitations across the reviewed studies.

CONCLUSIONS

Although at present the data do not warrant the utility of subtyping, further research aimed at patent gaps in the literature, including clearer operationalization of symptom subtypes, greater use of biological challenge paradigms and physiological and other more objective measures of fear and anxiety, and exploration of subtyping based on biological factors such as genetics, may support the future designation of panic attack subtypes and their ultimate clinical utility.

Interoceptive sensitivity in anxiety and anxiety disorders: an overview and integration of neurobiological findings

Interoceptive sensitivity, particularly regarding heartbeat, has been suggested to play a pivotal role in the pathogenesis of anxiety and anxiety disorders. This review provides an overview of methods which are frequently used to assess heartbeat perception in clinical studies and summarizes presently available results referring to interoceptive sensitivity with respect to heartbeat in anxiety-related traits (anxiety sensitivity, state/trait anxiety), panic disorder and other anxiety disorders. In addition, recent neurobiological studies of neuronal activation correlates of heartbeat perception using positron emission tomography (PET), functional magnetic resonance imaging (fMRI) or electroencephalographic (EEG) techniques are presented. Finally, possible clinical and therapeutic implications (e.g., beta-blockers, biofeedback therapy, cognitive interventions and interoceptive exposure) of the effects of heartbeat perception on anxiety and the anxiety disorders and the potential use of interoceptive sensitivity as an intermediate phenotype of anxiety disorders in future neurobiological and genetic studies are discussed.

Sleep-based heart period variability in panic disorder with and without nocturnal panic attacks

In this paper, we investigated ambulatory sleep heart period variability in panic disorder participants with nocturnal panic (NP) compared to daytime panic attacks only. A time-derived measure of heart period variability (HPV) during sleep was significantly reduced in the NP group (n=32) relative to the daytime panic (n=17) and nonanxious (n=17) control groups. Consistent with previous work, NP participants also reported greater fear of relaxation and sleep than daytime panic and control groups. Based on a neurovisceral model of attention [Thayer, J. F., & Lane, R. D. (2000). A model of neurovisceral integration in emotion regulation and dysregulation. Journal of Affective Disorders, 61, 210-216] that predicts that decreased HPV is related to disregulated behavioral adaptation, we hypothesized that HPV measured during sleep would be most reduced in NP participants. These findings indicate that HPV is related to nocturnal panic disorder insofar as it is measured during sleep.

Nocturnal panic and recent life events

Recent research has hypothesized an association between traumatic events and nocturnal panic (NP). The purpose of this study was to investigate whether the onset of nocturnal panic attacks is associated with a higher frequency of and/or greater severity of stressful or traumatic life events than that of patients with panic disorders (PDs) who experience daytime panic attacks (DPs) while awake. A secondary aim was to investigate whether NP is associated with specific life events at the onset of the disorder. Our sample comprised 129 subjects with PD (DSM-IV). We investigated the number and types of stressful life events that occurred in the year prior to PD onset using a semistructured interview. Of the sample, 28.7% had recurrent nocturnal panic attacks (NP group). Subjects with and without recurrent NP did not differ on any sociodemographic or clinical characteristic. Neither the number nor type of life event distinguished those with or without NP. The subgroup of patients with PD with recurrent NP appears to represent a variant of PD with a possible increased vulnerability to conditions of diminished arousal as a trigger of panic attacks. However, the hypothesis that this vulnerability might be determined by life events that occur in the period preceding PD onset was not supported by the findings of this study.

Cognitive behavior therapy for chronic insomnia occurring within the context of medical and psychiatric disorders

Insomnia is a pervasive problem for many patients suffering from medical and psychiatric conditions. Even when the comorbid disorders are successfully treated, insomnia often fails to remit. In addition to compromising quality of life, untreated insomnia may also aggravate and complicate recovery from the comorbid disease. Cognitive behavior therapy for insomnia (CBT-I) has an established efficacy for primary insomnia, but less is known about its efficacy for insomnia occurring in the context of medical and psychiatric conditions. The purpose of this article is to present a rationale for using CBT-I in medical and psychiatric disorders, review the extant outcome literature, highlight considerations for adapting CBT-I procedures in specific populations, and suggest directions for future research. Outcome studies were identified for CBT-I in mixed medical and psychiatric conditions, cancer, chronic pain, HIV, depression, posttraumatic stress disorder, and alcoholism. Other disorders discussed include: bipolar disorder, eating disorders, generalized anxiety, and obsessive compulsive disorder. The available data demonstrate moderate to large treatment effects (Cohen's d, range=0.35-2.2) and indicate that CBT-I is a promising treatment for individuals with medical and psychiatric comorbidity. Although the literature reviewed here is limited by a paucity of randomized, controlled studies, the available data suggest that by improving sleep, CBT-I might also indirectly improve medical and psychological endpoints. This review underscores the need for future research to test the efficacy of adaptations of CBT-I to disease specific conditions and symptoms.

Assessment and treatment of nocturnal panic attacks

Nocturnal panic (NP), waking from sleep in a state of panic, is a common occurrence among patients with panic disorder, with 44-71% reporting at least one such attack. NP is a non-REM event that is distinct from sleep terrors, sleep apnea, nightmares or dream-induced arousals. This review outlines recent advances in the characterization of NP, as well as current approaches to the assessment and treatment of NP. In contrast to earlier work, more recent studies suggest that patients with NP do not differ from patients without NP on sleep architecture, sleep physiology, self-reported sleep quality and severity of panic disorder. However, more precise measurement of physiological precipitants and features is warranted. Assessment of NP focuses on ruling out other explanations for NP, with differential diagnosis based on interviews, sleep polysomnography and ambulatory recording of sleep. Psychological treatment (cognitive-behavioral therapy) targets misappraisals of anxiety sensations, hyperventilatory response, and conditioned reactions to internal, physical cues. Recent evidence supports the efficacy of this approach, however, controlled studies on pharmacological agents in the treatment of NP are lacking. Research is needed to examine the effects of combined cognitive-behavioral therapy and medications, compared to medication alone in the treatment of NP.

Factors associated with insomnia among civilians seeking treatment for PTSD: an exploratory study

This study explored relationships between insomnia (as measured by Item 13 of the Clinician-Administered PTSD [Posttraumatic Stress Disorder] Scale) and other PTSD symptoms, comorbidity, and measures of depression, worry, and panic in a mixed-trauma sample of 143 treatment-seeking civilians with PTSD (median age 39.4 years, 83% female, 96% White). Regression analyses showed that, adjusting for sleep medication use, severity of nightmares and diminished interest in pleasurable activities accounted for unique variance in insomnia severity level. Severity of nightmares and depression accounted for unique variance in the presence of severe insomnia. Findings support a role for conditioning related to nightmares in the etiology of PTSD-related insomnia.

Reactivity to imagery and nocturnal panic attacks

We assessed psychophysiological responses to imagery of traumatic events, panic attacks, and loss of vigilance (i.e., being hypnotized) in participants diagnosed with panic disorder. Participants were either currently experiencing nocturnal panic or daytime panics only. It was hypothesized that nocturnal panickers would exhibit heightened responsivity to imagery of their worst panic and worst trauma, as well as being hypnotized, compared to day panickers. Using established imagery procedures, heart rate, skin conductance, and frontalis electromyogram were recorded as participants imagined each scene. Nocturnal and day panickers differed in their responses to the hypnosis scene only. As predicted, nocturnal panickers endorsed more panic symptoms in response to imagery of being hypnotized. Contrary to expectation, nocturnal and daytime panickers showed no differences in physiologic reactivity or self-reported distress to worst trauma or worst panic imagery. The findings are discussed with respect to the role of fear of loss of vigilance for nocturnal panic.

Fear of loss of vigilance: Development and preliminary validation of a self-report instrument

We describe the development and initial validation of the Fear of Loss of Vigilance Questionnaire (FLOVQ). Recent investigations indicate that individuals with nocturnal panic (NP) demonstrate increased anxiety and panic in response to meditative relaxation and imagined hypnosis, compared to those with daytime panic (DP) only, suggesting that NP individuals fear situations that involve a loss of vigilance (e.g., relaxation, fatigue and altered states of consciousness). The FLOVQ was designed to assess this construct and was tested in five non-clinical samples and one clinical sample. The 14-item instrument demonstrated good internal consistency and test-retest reliability. Non-clinical respondents who experienced NP endorsed greater fear of loss of vigilance than non-panickers; those who only experienced DP did not differ from the other groups. By contrast, on measures of trait and state anxiety, and anxiety sensitivity, both panic groups scored higher than non-panickers, suggesting that these latter measures were related to broader factors pertaining to a general tendency to panic versus a specific factor associated with NP. No group differences were found between NPs and DPs in either the non-clinical or the clinical sample, suggesting that fear of loss of vigilance may be a vulnerability factor for the development of NP and that the FLOVQ has more utility as a research rather than as a clinical instrument.

Does nocturnal panic represent a more severe form of panic disorder?

Nocturnal panic (NP), or waking from sleep in a state of panic, occurs in 18% to 45% of panic disorder patients. This relatively common phenomenon, however, is not well understood. In this study, the authors tested the hypotheses that NP represents a more severe form of panic disorder or is a manifestation of heightened vulnerability to sleep disturbance. Patients with NP ( = 51) were compared with patients with panic disorder without a history of NP ( = 41) on measures of panic disorder severity, comorbidity, interpersonal functioning, and sleep disturbance. There was no evidence for more severe psychopathology and only weak evidence for more sleep disturbance. Instead, patients with NP showed less agoraphobic avoidance, perhaps suggesting that they are less likely to associate panic with situational factors. The authors conclude that NP may be a specific version of panic disorder characterized by fearful associations with sleep and sleeplike states.