Virtual Reality Breathing Interventions for Mental Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Breathing exercises have been shown to reduce mental health problems among clinical and non-clinical populations. Although virtual reality (VR) breathing interventions are assumed to have potential benefits, it remains unclear whether VR breathing interventions are more effective at improving mental health than non-VR breathing interventions. We conducted a systematic literature search in six electronic databases (Web of Science, PsycINFO, Embase, Cochrane Central Register of Controlled Trials, Scopus, and PubMed) from inception to 30th September, 2022. We included randomized controlled trials in adults evaluating effects of VR compared to non-VR breathing interventions on primary outcomes of mental health (stress, anxiety and mood), and secondary outcomes of physiological stress measures (e.g., heart rate (HR), heart rate variability (HRV)). Within these selected studies, we explored differences in likeability and future use between VR and non-VR breathing interventions. 2.848 records were identified of which 65 full-text articles were assessed. Six RCTs were included, of which five were suitable for meta-analyses. Comparing VR to non-VR breathing interventions, there were no significant differences in overall mental health, stress, anxiety or mood, nor in HR or HRV. There was no evidence that participants liked VR breathing interventions more than non-VR, nor would use them more in the future. These results suggest that there is no evidence that VR breathing interventions are more effective than non-VR in improving mental health outcomes, HR, HRV. Further research is required to determine whether there may be advantages to longer-term VR-implementation and practice, and explore possible mechanisms.

The association between pain-related psychological variables and postural control in low back pain: A systematic review and meta-analysis.

BACKGROUND: Alterations in postural control have been found in individuals with low back pain (LBP), particularly during challenging postural tasks. Moreover, higher levels of negative pain-related psychological variables are associated with increased trunk muscle activity, reduced spinal movement, and worse maximal physical performance in individuals with LBP. RESEARCH QUESTION: Are pain-related psychological variables associated with postural control during static bipedal standing tasks in individuals with LBP? METHODS: A systematic review and meta-analysis were conducted. Pubmed, Web of Science, and PsycINFO were searched until March 2023. Studies were included if they evaluated postural control during static bipedal standing in individuals with LBP by measuring center of pressure (CoP) variables, and reported at least one pain-related psychological variable. Correlation coefficients between pain-related psychological variables and CoP variables were extracted. Study quality was assessed with the "Quality In Prognosis Studies" tool (QUIPS). Random-effect models were used to calculate pooled correlation coefficients for different postural tasks. Sub-analyses were performed for positional or dynamic CoP variables. Certainty of evidence was assessed with an adjusted "Grading of Recommendations, Assessment, Development, and Evaluations" tool (GRADE). The protocol was registered on PROSPERO (CRD42021241739). RESULTS: Sixteen studies (n = 723 participants) were included. Pain-related fear (16 studies) and pain catastrophizing (three studies) were the only reported pain-related psychological variables. Both pain-related fear (-0.04 < pooled r < 0.14) and pain catastrophizing (0.28 < pooled r < 0.29) were weakly associated with CoP variables during different postural tasks. For all associations, the certainty of evidence was very low. SIGNIFICANCE: Pain-related fear and pain catastrophizing are only weakly associated with postural control during static bipedal standing in individuals with LBP, regardless of postural task difficulty. Certainty of evidence is very low thus it is conceivable that future studies accounting for current study limitations might reveal different findings.

Testing emotional response coherence assumptions: Comparing emotional versus non-emotional states.

Although central to theories of emotion, emotional response coherence, that is, coordination among various emotion response systems, has received inconsistent empirical support. This study tests a basic assumption of response coherence, that is, that it characterizes emotional states defining their beginning and end. To do so, we (a) compare response coherence between emotional versus non-emotional states and (b) examine how emotional coherence changes over time, before, during, and after an emotional episode. Seventy-nine participants viewed neutral, pleasant, and unpleasant film clips and rated continuously how pleasant they felt (experience) before (anticipation), during, and after (recovery) each clip. Autonomic physiological arousal responses (skin conductance level, heart rate; physiology) and facial expressions (corrugator, zygomatic activity; expression) were recorded. Within-person cross-correlations between all emotional response pairs were calculated for each phase. Analyses comparing coherence during emotional versus neutral film viewing showed that only experience-expression coherence was higher for emotional versus neutral films, indicating specificity for emotional states. Examining coherence across phases indicated that coherence increased from anticipation to emotional film viewing, as expected, for experience-expression and experience-physiology pairs (SCL only). Of those pairs, increased coherence returned to baseline during recovery, as theoretically assumed, only for experience-corrugator activity coherence. Current findings provide empirical support for theoretical views of response coherence as a defining feature of emotional episodes, but mostly for the coherence between experience and facial expressions. Further research needs to investigate the role of sympathetic arousal indices, as well as the role of response coherence in emotional recovery.

Respiratory psychophysiology and COVID-19: A research agenda.

After multiple waves of the COVID-19 pandemic, it has become clear that the impact of SARS-CoV-2 will carry on for years to come. Acutely infected patients show a broad range of disease severity, depending on virus variant, vaccination status, age and the presence of underlying medical and physical conditions, including obesity. Additionally, a large number of patients who have been infected with the virus present with post-COVID syndrome. In September 2020, the International Society for the Advancement of Respiratory Psychophysiology organized a virtual interest meeting on 'Respiratory research in the age of COVID-19', which aimed to discuss how research in respiratory psychophysiology could contribute to a better understanding of psychophysiological interactions in COVID-19. In the resulting current paper, we propose an interdisciplinary research agenda discussing selected research questions on acute and long-term neurobiological, physiological and psychological outcomes and mechanisms related to respiration and the airways in COVID-19, as well as research questions on comorbidity and potential treatment options, such as physical rehabilitation.

Categorical interoception: the role of disease context and individual differences in habitual symptom reporting.

OBJECTIVE: Symptom reports correspond less to physiological dysfunction in persons with high levels of symptoms in daily life and in patients with functional somatic symptoms, suggesting poor symptom perception. In this study, we investigated whether interoception was impacted by the meaning of the context and by habitual symptom reporting. METHODS: Eight inspiratory resistances that were equidistant in intensity were administered to healthy women (N = 124) varying in habitual symptom reporting. One group was asked to categorise them as benign sensations vs. as bodily symptoms that could suggest a disease (disease context group). Another group was asked to categorise them as low- vs. high-intensity sensations (neutral context group). MAIN OUTCOME: Perceived differences in intensity within- vs. between-category and unpleasantness, categorisation threshold, and the reliability of categorising each stimulus were examined in relation to context (disease, neutral) and symptom reporting levels in daily life. RESULTS: Context (neutral vs. disease) impacted intensity and unpleasantness perception. Processing of respiratory interoceptive stimulation was more detailed, elaborate, and cautious when categorising stimuli as signalling health or disease vs. as low- or high-intensity. Individual differences in habitual symptoms had no effect. CONCLUSION: The pattern of results suggests that these categorisation effects indicate flexible, context-sensitive interoceptive processing, which may characterise healthy individuals.

A novel self-report scale of interoception: the three-domain interoceptive sensations questionnaire (THISQ).

OBJECTIVES: The self-reported perception of bodily sensations is assumed predictive for health and disease. Existing questionnaires mostly focus on aversive sensations, and associated emotions and cognitions, which potentially confounds associations between interoception and illness. Therefore, we developed the Three-domain Interoceptive Sensations Questionnaire (THISQ), assessing self-reported perception of neutral respiratory, cardiac, and gastroesophageal sensations. DESIGN: Using cross-sectional surveys, we developed and validated the THISQ. MAIN OUTCOME MEASURES: In Sample 1 (n = 357), a pool of 28 Dutch items was subjected to exploratory factor analysis. Eighteen items with a primary factor loading >.40 were retained for confirmatory factor analysis in Sample 2 (n = 374) and Sample 3 (n = 484) for the validation of the Dutch and English questionnaire, respectively. RESULTS: Analyses supported the 3-factor solution: cardiorespiratory activation, cardiorespiratory deactivation, and gastroesophageal sensations. Scales showed acceptable to good internal consistency. Convergent validity was confirmed by significant medium associations between THISQ scores and other self-report measures of interoception. Divergent validity was supported by non-significant or small associations with measures of negative affectivity and symptom-related anxiety. CONCLUSION: Our findings suggest that the Dutch and English THISQs are valid and reliable self-report measures of interoception, which could advance our understanding of interoceptive processes in health and disease.Supplemental data for this article is available online at https://doi.org/10.1080/08870446.2021.2009479 .

The sigh and related behaviors.

Breathing is a critical, complex, and highly integrated behavior. Normal rhythmic breathing, also referred to as eupnea, is interspersed with different breathing related behaviors. Sighing is one of such behaviors, essential for maintaining effective gas exchange by preventing the gradual collapse of alveoli in the lungs, known as atelectasis. Critical for the generation of both sighing and eupneic breathing is a region of the medulla known as the preBötzinger Complex (preBötC). Efforts are underway to identify the cellular pathways that link sighing as well as sneezing, yawning, and hiccupping with other brain regions to better understand how they are integrated and regulated in the context of other behaviors including chemosensation, olfaction, and cognition. Unraveling these interactions may provide important insights into the diverse roles of these behaviors in the initiation of arousal, stimulation of vigilance, and the relay of certain behavioral states. This chapter focuses primarily on the function of the sigh, how it is locally generated within the preBötC, and what the functional implications are for a potential link between sighing and cognitive regulation. Furthermore, we discuss recent insights gained into the pathways and mechanisms that control yawning, sneezing, and hiccupping.

Bottom-Up and Cognitive Top-Down Emotion Regulation: Experiential Emotion Regulation and Cognitive Reappraisal on Stress Relief and Follow-Up Sleep Physiology.

Emotional stress throughout the day is known to affect objective sleep physiology and subjective sleep quality. In the interplay between emotions and sleep, emotion regulation plays a critical role in the recovery from stressful, emotional events and subsequent sleep. While the effects of top-down emotion regulation strategies such as cognitive reappraisal on sleep have been studied before, the impact of bottom-up emotion regulation strategies such as experiential emotion regulation is understudied. Cognitive reappraisal reflects the cognitive reinterpretation of the meaning of a stressful event, while experiential emotion regulation involves an active, non-intervening, accepting, open and welcoming approach of acknowledging awareness of raw sensory affective experiences or 'experiential awareness' in a first phase and expression in a second phase. The present study aims to investigate the effects of experiential emotion regulation and cognitive reappraisal on the recovery from pre-sleep emotional stress measured by (1) negative affect and (2) sleep structure. Sleep of forty-three healthy Dutch-speaking participants (22 females, 21 males) has been assessed using EEG polysomnography. Stress was triggered using a pre-sleep emotional failure induction, after which emotion regulation by experiential emotion regulation versus cognitive reappraisal versus control was induced twice. The control condition consisted of the reallocation of attention towards the neutral aspects of the emotional event. The results indicated that recovery from negative affect of the failure experience after single or repeated deployment of experiential emotion regulation and cognitive reappraisal was not significantly different from the control condition. Moreover, after repeated deployment, sleep physiology did not significantly differ between experiential emotion regulation, cognitive reappraisal, and the control condition in the impact of the regulation of the failure experience. The implications of the distinctive impact of experiential emotion regulation and cognitive reappraisal on both the pre-sleep emotional experience and follow-up sleep physiology are discussed.

The psychophysiology of the sigh: II: The sigh from the psychological perspective.

A sigh is a distinct respiratory behavior with specific psychophysiological roles. In two accompanying reviews we will discuss the physiological and psychological functions of the sigh. The present review will focus on the psychological functions of the sigh. We discuss the regulatory effects of a sigh, and argue how these effects may become maladaptive when sighs occur excessively. The adaptive role of a sigh is discussed in the context of regulation of psychophysiological states. We propose that sighs facilitate transitions from one psychophysiological state to the next, and this way contribute to psychophysiological flexibility, via a hypothesized resetting mechanism. We discuss how a sigh resets respiration, by controlling mechanical and metabolic properties of respiration associated with respiratory symptoms. Next, we elaborate on a sigh resetting emotional states by facilitating emotional transitions. We attempt to explain the adaptive and maladaptive functions of a sigh in the framework of stochastic resonance, in which we propose occasional, spontaneous sighs to be noise contributing to psychophysiological regulation, while excessive sighs result in psychophysiological dysregulation. In this context, we discuss how sighs can contribute to therapeutic interventions, either by increasing sighs to improve regulation in case of a lack of sighing, or by decreasing sighs to restore regulation in case of excessive sighing. Finally, a research agenda on the psychology of sighs is presented.

The psychophysiology of the sigh: I: The sigh from the physiological perspective.

Breathing is composed of multiple, distinct behaviors that are bidirectionally regulated through autonomic and voluntary mechanisms. One behavioral component is the sigh, which serves distinct physiological and psychological roles. In two accompanying reviews we will discuss these roles. The present review focuses on the physiological function, where sighs play a critical role in controlling lung compliance by preventing the collapse of alveoli. Implicated in the generation of sighs and normal breathing is the preBötzinger Complex, a rhythmogenic network in the medulla. Although sighs and normal inspiration are generated within the same network, they show distinct temporal characteristics. While sighs occur every few minutes, normal breathing is generated in the range of seconds. Both are differentiated by distinct modulatory and synaptic mechanisms, and recent evidence indicates that these mechanisms are regulated by inputs from different regions of the brain. An important modulator of sighs is hypoxia, implicating sighs in the arousal response.

Expectation and dyspnoea: the neurobiological basis of respiratory nocebo effects.

Cues such as odours that do not per se evoke bronchoconstriction can become triggers of asthma exacerbations. Despite its clinical significance, the neural basis of this respiratory nocebo effect is unknown.We investigated this effect in a functional magnetic resonance imaging (fMRI) study involving 36 healthy volunteers. The experiment consisted of an experience phase in which volunteers experienced dyspnoea while being exposed to an odorous gas ("Histarinol"). Volunteers were told that Histarinol induces dyspnoea by bronchoconstriction. This was compared with another odorous gas which did not evoke dyspnoea. Dyspnoea was actually induced by a concealed, resistive load inserted into the breathing system. In a second, expectation phase, Histarinol and the control gas were both followed by an identical, very mild load. Respiration parameters were continuously recorded and participants rated dyspnoea intensity after each trial.Dyspnoea ratings were significantly higher in Histarinol compared with control conditions, both in the experience and in the expectation phase, despite identical physical resistance in the expectation phase. Insula fMRI signal matched the actual load, i.e. a significant difference between Histarinol and control in the experience phase, but no difference in the expectation phase. The periaqueductal gray showed a significantly higher fMRI signal during the expectation of dyspnoea. Finally, Histarinol-related deactivations during the expectation phase in the rostral anterior cingulate cortex mirrored similar responses for nocebo effects in pain.These findings highlight the neural basis of expectation effects associated with dyspnoea, which has important consequences for our understanding of the perception of respiratory symptoms.

The respiratory occlusion discrimination task: A new paradigm to measure respiratory interoceptive accuracy.

Interoception, or the sense of the internal state of the body, is hypothesized to be essential for a wide range of psychobiological processes and the development and perpetuation of several (mental) health problems. However, the study of interoceptive accuracy, the objectively measured capacity to detect or discriminate conscious bodily signals, has been hampered by the use of tasks with questionable construct validity and is often limited to studying interoception solely in the cardiac domain. We developed a novel task to measure interoceptive accuracy in the respiratory domain, the respiratory occlusion discrimination (ROD) task. In this task, interoceptive accuracy is defined as an individual's ability to detect small differences in lengths of short respiratory occlusions, assessed by means of an adaptive staircase procedure. This article describes a validation study (N = 97) aimed at investigating the internal consistency, test-retest reliability, and discriminant validity of the ROD task. The average just noticeable difference of lengths of respiratory occlusion was 74.22 ms, with large inter-individual variability (SD = 37.1 ms). The results of the validation study indicate acceptable internal consistency (Cronbach's alpha = 0.70), 1-week test-retest reliability (r = 0.53), and discriminant validity, as indicated by a lack of correlation between the ROD task and an auditory discrimination task with identical design (r = 0.18), and a weak correlation with breathing behavior (r = -0.27). The ROD task is a promising novel paradigm to study interoceptive accuracy and its role in various psychobiological processes and disorders.

Adaptive and maladaptive emotion processing and regulation, and the case of alexithymia.

In this conceptual review, we discuss models of emotion and its regulation and identify a spectrum of processes that characterise adaptive adjustment to the affective environment. We describe a dynamic-phasic model of emotion processing and regulation, focusing on five stages: anticipation, response, recovery, habituation and rest as part of a cascade of responses to emotional challenges, as these become progressively expected, proximal, chronic or repeated. We argue for the need to investigate beyond simple reactivity to emotional stimuli, in order to understand mental and physical health conditions where emotional dysregulation plays a role. We propose that a hallmark of an effective and adaptive emotion regulation system is its flexibility, in the service of life goals and values. Consistent with McEwen's model (1998, Stress, adaptation, and disease: Allostasis and allostatic load. Annals of the New York Academy of Sciences, 840(1), 33-44), inflexible emotion regulation can lead to increased allostatic load, from frequent stress, inadequate reactivity, failed shutdown and habituation, which may result in physical and mental illness. Alexithymia exemplifies inflexible emotion regulation, with dysfunctions potentially across all stages of emotion processing, both psychologically and physiologically. These maladaptive processes and their consequence on allostatic load potentially explain the association between alexithymia and physical and mental illness.

Respiratory Variability, Sighing, Anxiety, and Breathing Symptoms in Low- and High-Anxious Music Students Before and After Performing.

Music performance anxiety (MPA) is a major problem for music students. It is largely unknown whether music students who experience high or low anxiety differ in their respiratory responses to performance situations and whether these co-vary with self-reported anxiety, tension, and breathing symptoms. Affective processes influence dynamic respiratory regulation in ways that are reflected in measures of respiratory variability and sighing. This study had two goals. First, we determined how measures of respiratory variability, sighing, self-reported anxiety, tension, and breathing symptoms vary as a function of the performance situation (practice vs. public performance), performance phase (pre-performance vs. post-performance), and the general MPA level of music students. Second, we analyzed to what extent self-reported anxiety, tension, and breathing symptoms co-vary with the respiratory responses. The participants were 65 university music students. We assessed their anxiety, tension, and breathing symptoms with Likert scales and recorded their respiration with the LifeShirt system during a practice performance and a public performance. For the 10-min periods before and after each performance, we computed number of sighs, coefficients of variation (CVs, a measure of total variability), autocorrelations at one breath lag (ARs(1), a measure of non-random variability) and means of minute ventilation (V'E), tidal volume (VT), inspiration time (TI), and expiration time (TE). CVs and sighing were greater whereas AR(1) of V'E was lower in the public session than in the practice session. The effect of the performance situation on CVs and sighing was larger for high-MPA than for low-MPA participants. Higher MPA levels were associated with lower CVs. At the within-individual level, anxiety, tension, and breathing symptoms were associated with deeper and slower breathing, greater CVs, lower AR(1) of V'E, and more sighing. We conclude that respiratory variability and sighing are sensitive to the performance situation and to musicians' general MPA level. Moreover, anxiety, tension, breathing symptoms, and respiratory responses co-vary significantly in the context of music performance situations. Respiratory monitoring can add an important dimension to the understanding of music performance situations and MPA and to the diagnostic and intervention outcome assessments of MPA.

Sighs can become learned behaviors via operant learning.

Sighs have important physiological and psychological regulatory functions. These rewarding effects of a sigh potentially reinforce sighing in situations that require physiological and/or psychological regulation. The present study aimed to investigate whether sighs can become learned behaviors via operant learning. In two studies, we manipulated the effect of spontaneous sighs in response to dyspnea relief, by either punishing a sigh by the onset of dyspnea, or not punishing a sigh by continued dyspnea relief. Results show that sigh rates in response to cues predicting the punishment of sighs are 1.20-1.28 times lower than sigh rates in response to cues predicting no punishment of sighs. These findings suggest that sighs can become learned behaviors via operant learning, contributing to both maladaptive sighing, potentially leading to respiratory dysregulation and respiratory complaints, and to adaptive sighing. Furthermore, these findings suggest new clinical practices to increase and decrease sigh rates during breathing training.

Categorical interoception and the role of threat.

Interoceptive fears and biased interoception are important characteristics of somatic symptom disorders. Categorization of interoceptive sensations impacts perception of their intensity and unpleasantness. In this study we investigated whether making interoceptive categories threat-relevant further biases interoception of individual sensations compared to safe categories. Either a category containing low- or high-intensity stimuli was made threat-relevant by instructing (and occasionally experiencing) that interoceptive sensations could be followed by an unpredictable electrocutaneous stimulus. We replicated that categorization had a profound impact on perceived interoceptive sensations, with stimuli within categories being perceived as more similar than equidistant stimuli at the category border. We found some evidence for the impact of threat on perceived characteristics of stimuli (with the direction of these effects depending on whether interoceptive stimuli of low or high intensity were threat-relevant), but not for altered categorical choice behaviour. These results imply that the perception of respiratory stimuli is influenced strongly by top-down processes such as categorization, and suggest that interoceptive processing may flexibly adapt to contextual factors such as threat in healthy individuals. However, inflexible responding to repeated and/or severe threat to the internal body may compromise accurate interoception and may result in interoceptive illusions contributing to medically unexplained symptoms and syndromes.

Habituation of the electrodermal response - A biological correlate of resilience?

Current approaches to quantifying resilience make extensive use of self-reported data. Problematically, this type of scales is plagued by response distortions-both deliberate and unintentional, particularly in occupational populations. The aim of the current study was to develop an objective index of resilience. The study was conducted in 30 young healthy adults. Following completion of the Connor-Davidson Resilience Scale (CD-RISC) and Depression/Anxiety/Stress Scale (DASS), they were subjected to a series of 15 acoustic startle stimuli (95 dB, 50 ms) presented at random intervals, with respiration, skin conductance and ECG recorded. As expected, resilience (CD-RISC) significantly and negatively correlated with all three DASS subscales-Depression (r = -0.66, p<0.0001), Anxiety (r = -0.50, p<0.005) and Stress (r = -0.48, p<0.005). Acoustic stimuli consistently provoked transient skin conductance (SC) responses, with SC slopes indexing response habituation. This slope significantly and positively correlated with DASS-Depression (r = 0.59, p<0.005), DASS-Anxiety (r = 0.35, p<0.05) and DASS-Total (r = 0.50, p<0.005) scores, and negatively with resilience score (r = -0.47; p = 0.006), indicating that high-resilience individuals are characterized by steeper habituation slopes compared to low-resilience individuals. Our key finding of the connection between habituation of the skin conductance responses to repeated acoustic startle stimulus and resilience-related psychometric constructs suggests that response habituation paradigm has the potential to characterize important attributes of cognitive fitness and well-being-such as depression, anxiety and resilience. With steep negative slopes reflecting faster habituation, lower depression/anxiety and higher resilience, and slower or no habituation characterizing less resilient individuals, this protocol may offer a distortion-free method for objective assessment and monitoring of psychological resilience.

A sigh of relief or a sigh of expected relief: Sigh rate in response to dyspnea relief.

Research has suggested that sighs may serve a regulatory function during stress and emotions by facilitating relief. Evidence supports the hypotheses that sighs both express and induce relief from stress. To explore the potential role of sighs in the regulation of symptoms, the present study aimed to investigate the relationship between sighs and relief of symptoms, and relief of dyspnea, specifically. Healthy volunteers participated in two studies (N = 44, N = 47) in which dyspnea was induced by mild (10 cmH2 O/l/s) or high (20 cmH2 0/l/s) inspiratory resistances. Dyspnea relief was induced by the offset of the inspiratory resistances (transitions from high and mild inspiratory resistance to no resistance). Control comparisons included dyspnea increases (transitions from no or mild inspiratory resistance to high inspiratory resistance) and dyspnea continuations (continuations of either no resistance or a high resistance). In Experiment 1, dyspnea levels were cued. In Experiment 2, no cues were provided. Sigh rate during dyspnea relief was significantly higher compared to control conditions, and sigh rate increased as self-reported dyspnea decreased. Additionally, sigh rate was higher during cued dyspnea relief compared to noncued dyspnea relief. These results suggest that sighs are important markers of dyspnea relief. Moreover, sighs may importantly express dyspnea relief, as they are related to experiential dyspnea decreases and occur more frequently during expected dyspnea relief. These findings suggest that sighs may not only be important in the regulation of stress and emotions, but also may be functional in the regulation of dyspnea.

Sigh rate during emotional transitions: More evidence for a sigh of relief.

Evidence suggests that sighs regulate stress and emotions, e.g. by facilitating relief. This study aimed to investigate sigh rates during relief. In addition, links between sighs, anxiety sensitivity and HPA-axis activity were explored. Healthy volunteers (N=29) were presented cues predicting the valence of subsequent stimuli. By sequencing cues that predicted pleasant or unpleasant stimuli with or without certainty, transitions to certain pleasantness (relief) or to certain unpleasantness (control) were created and compared to no transitions. Salivary cortisol, anxiety sensitivity and respiration were measured. Sigh frequency was significantly higher during relief than during control transitions and no transition states, and higher during control transitions than during no transition states. Sigh frequency increased with steeper cortisol declines for high anxiety sensitive persons. Results confirm a relationship between sighs and relief. In addition, results suggest that sigh frequency is importantly related to HPA-axis activity, particularly in high anxiety sensitive persons.