Recent studies have focused on investigating different factors that may affect heart rate variability (HRV),pointing especially to the effects of age, gender and stress level. Other findings raise the importance of consid- ering the respiratory frequency in the analysis of HRV signals. In this study, we evaluate the effect of several covariates on the parameters of a stochastic model for HRV. The data was recorded from 47 test participants, whose breathing was controlled by following a metronome with increasing frequency. This setup allows for a controlled acquisition of respiratory related HRV data covering the frequency range in which adults breathe in different everyday situations. A stochastic model, known as Locally Stationary Chirp Process, accounts for the respiratory signal information and models the HRV data. The model parameters are estimated with a novel inference method based on the separability features possessed by the process covariance function. Least square regression analysis using several available covariates is used to investigate the correlation with the stochastic model parameters. The results show statistically significant correlation of the model parameterswith age, BMI, State and Trait Anxiety as well as stress level.

Estimates of heart rate variability (HRV), and particularly parameters related to high frequency HRV (HF-HRV), are in-creasingly used as a proxy of cardiac parasympathetic nervous system regulation. Reduced HF-HRV is related to attention deficits, depression, various anxiety disorders, long-term work related stress or burnout, and cardiovascular diseases [1,2]. In this work, a stochastic model, known as

Locally Stationary Processes, [3], is applied to HRV data sequences from 47 test participants. The model parameters are estimated with a novel inference method and regression using a number of available covariates is used to investigate their correlation with the stochastic model parameters.

In this paper, we propose a novel framework for the analysis of task-related heart rate variability (HRV). Respiration and HRV are measured from 92 test participants while performing a chirp-breathing task consisting of breathing at a slowly increasing frequency under metronome guidance. A non-stationary stochastic model, belonging to the class of Locally Stationary Chirp Processes, is used to model the task-related HRV data, and its parameters are estimated with a novel inference method. The corresponding optimal mean-square error (MSE) time-frequency spectrum is derived and evaluated both with the individually estimated model parameters and the common process parameters. The results from the optimal spectrum are compared to the standard spectrogram with different window lengths and the Wigner-Ville spectrum, showing that the MSE optimal spectral estimator may be preferable to the other spectral estimates because of its optimal bias and variance properties. The estimated model parameters are considered as response variables in a regression analysis involving several physiological factors describing the test participants’ state of health, finding a correlation with gender, age, stress, and fitness. The proposed novel approach consisting of measuring HRV during a chirp-breathing task, a corresponding time-varying stochastic model, inference method, and optimal spectral estimator gives a complete framework for the study of task-related HRV in relation to factors describing both mental and physical health and may highlight otherwise overlooked correlations. This approach may be applied in general for the analysis of non-stationary data and especially in the case of task-related HRV, and it may be useful to search for physiological factors that determine individual differences.

Experimental research on stress recovery in natural environments is limited, as is study of the effect of sounds of nature. After inducing stress by means of a virtual stress test, we explored physiological recovery in two different virtual natural environments (with and without exposure to sounds of nature) and in one control condition. Cardiovascular data and saliva cortisol were collected. Repeated ANOVA measurements indicated parasympathetic activation in the group subjected to sounds of nature in a virtual natural environment, suggesting enhanced stress recovery may occur in such surroundings. The group that recovered in virtual nature without sound and the control group displayed no particular autonomic activation or deactivation. The results demonstrate a potential mechanistic link between nature, the sounds of nature, and stress recovery, and suggest the potential importance of virtual reality as a tool in this research field.

This study examined age differences in phasic heart rate in response to neutral, negative and positive pictures. Heart rate changes and subjective ratings were analyzed in 22 middle-aged (40-55 years) and 30 older (56-78 years) participants. The effects of valence on the HR pattern across time were similar to that obtained by Bradley and co-workers. Conversely to previous studies, we did not report any age-related reduction in cardiac reactivity. Instead, when viewing positive pictures, the triphasic wave form appeared in the group of older adults, but for younger participants, it was replaced by a sustained deceleration. These results were interpreted in the light of the socioemotional selectivity theory.

INTRODUCTION: After a hypnotic induction, medium and highly hypnotizable individuals often report spontaneous alterations in various dimensions of consciousness. Few studies investigating these experiences have controlled for the inherent demands of specific hypnotic suggestions and fewer still have considered their dynamic properties and neural correlates.

METHODS: We adopted a neurophenomenological approach to investigate neutral hypnosis, which involves no specific suggestion other than to go into hypnosis, with 37 individuals of high, medium, and low hypnotizability (Highs, Mediums, and Lows). Their reports of depth and spontaneous experience at baseline, following a hypnotic induction, and then after multiple rest periods were analyzed and related to EEG frequency band power and global functional connectivity.

RESULTS: Hypnotizability was marginally associated with lower global functional connectivity during hypnosis. Perceived hypnotic depth increased substantially after the induction especially among Highs and then Mediums, but remained almost unchanged among Lows. In the sample as a whole, depth correlated moderately to strongly with power and/or power heterogeneity for the fast EEG frequencies of beta2, beta3, and gamma, but independently only among Highs. The spontaneous phenomenology of Lows referred primarily to the ongoing experiment and everyday concerns, those of Mediums to vestibular and other bodily experiences, and those of Highs to imagery and positive affect/exceptional experiences. The latter two phenomena were associated with lower global functional connectivity during hypnosis. Imagery correlated positively with gamma power heterogeneity and negatively with alpha1 power heterogeneity. Generally, the pattern of correlations for the Highs was the opposite of that for the Lows.

CONCLUSIONS: Experienced hypnotic depth and spontaneous phenomena following a neutral hypnotic induction vary as a function of hypnotizability and are related to global functional connectivity and EEG band wave activity.

This study (N = 37 with high, medium, and low hypnotizables) evaluated depth reports and EEG activity during both voluntary and hypnotically induced left-arm lifting with sLORETA functional neuroimaging. The hypnotic condition was associated with higher activity in fast EEG frequencies in anterior regions and slow EEG frequencies in central-parietal regions, all left-sided. The voluntary condition was associated with fast frequency activity in right-hemisphere central-parietal regions and slow frequency activity in left anterior regions. Hypnotizability did not have a significant effect on EEG activity, but hypnotic depth correlated with left hemisphere increased anterior slow EEG and decreased central fast EEG activity. Hypnosis had a minimal effect on depth reports among lows, a moderate one among mediums, and a large one among highs. Because only left-arm data were available, the full role of the hemispheres remains to be clarified.

Introduction

A large body of studies has showed that the ability to learn new information is impaired when we are sleep deprived. Pattern separation (PS), the ability to form distinct memories for events that are highly similar and share overlapping features, has also previously been found to be impaired by sleep deprivation. In the present study, we examined if a daytime nap would increase PS performance.

Methods

108 young healthy participants came to the lab in the morning and completed the Mnemonic Similarity Task (MST). This task starts with an encoding phase where participants view images of common everyday objects and are asked to classify them as indoor or outdoor objects. During a subsequent memory test, participants view three different kinds of objects; ‘old’ objects that were also present during the encoding phase, ‘new’ objects that have not been seen before, and ‘lure’ objects that are similar to, but not exactly the same as, objects viewed during encoding. The task of the participants during the re-test is to say if the objects presented are ‘old’, ‘new’ or ‘similar’. This test gives two different outcome measures: General Recognition (GR) - the ability to separate old objects from new ones, and PS - the ability to separate similar objects from old ones. After this task, participants were randomly allocated to either a sleep or a wake group. The sleep group had a two-hour nap opportunity and the wake group spent an equal amount of time resting. After this delay interval, participants completed the MST for a second time with a new set of images.

Results

Results revealed no support for sleep in increasing either GR or PS ability. Within the sleep group, there were no correlations between changes in PS ability and time spent in any sleep stage.

Conclusion

Previous studies that have found a role of sleep for PS ability has done so using larger manipulation of sleep. Based on the present study however, just a short daytime nap does not seem to have any effect on PS ability.

The aim of this study was to examine how a daytime nap affected the consolidation of fear learning. Participants first underwent fear conditioning during which they were exposed to a large and a small circle. One of these was repeatedly paired with an electric shock (making it the CS+), whereas the other circle was never paired with the shock (the CS-). After a delay interval containing either a nap or wake, participants again viewed the CS+ and the CS- intermixed with eight novel circles that varied in size between the two stimuli seen before, as well as a blue triangle that served as a novel stimulus without prior fear relevance. We examined both fear retention (the difference between the CS+ and the CS-) as well as fear generalization (responses to the novel stimuli based on their similarity to the original CS+). Contrary to previous studies, results from the participants who acquired a differentiated fear response during the acquisition phase revealed that the wake group showed significantly larger skin conductance responses to the CS+ compared to the CS-, whereas no such difference was present in the sleep group. These results were not driven by differences in explicit memory or by differences in general reactivity. Analyzing responses to the novel stimuli revealed a tendency towards a more generalized response in the sleep group, with no differences between the CS+ and any other stimulus, whereas the wake group showed increased responses to the stimuli depending on their similarity to the original CS+. This effect was however only present when controlling for baseline differences in worry.

Fear conditioning is an important survival mechanism, as is the ability to generalize learned fear responses to stimuli that are similar to the original conditioned stimulus. Overgeneralization of fear learning, prominent in many anxiety disorders, is however highly maladaptive. Because sleep is involved in the consolidation of fear learning, and in active processing of information, the present study explored the effect of sleep on generalization of fear learning. Participants watched a random sequence of pictures of a small and a big circle, one of them coupled with an aversive sound. Then, after a delay period containing either a nap or wake, generalization was examined as participants watched the two circles again, together with eight novel circles that gradually varied in size between the former two. Results showed that the fear response increased as a function of similarity to the conditioned response. However, there was no difference in the degree of generalization between the sleep and the wake group.

We investigated the duration of suppression-induced forgetting (SIF), and the extent to which retrieval suppression differs between negative and neutral memories. We further examined if SIF was differently affected by sleep versus wake during the delay interval between retrieval suppression and re-test. Fifty participants first learned to associate neutral words with either neutral or negative images. Then, a subset of the words was shown again, and participants were asked to either recall (Think), or to suppress retrieval of (No-Think) the associated images. Finally, a memory test for all items was performed either immediately after the Think/No-Think (T/NT) phase (No Delay), or after a 3.5 h delay interval containing either sleep or wake. Results revealed a SIF effect only in the No Delay group, indicating that this forgetting effect dissipates already after a 3.5 h delay interval. Negative items were experienced as more intrusive than neutral ones during the T/NT phase.

Sleep has been found to have a beneficial effect on memory consolidation. It has furthermore frequently been suggested that sleep does not strengthen all memories equally. The first aim of this review paper was to examine whether sleep selectively strengthens emotional declarative memories more than neutral ones. We examined this first by reviewing the literature focusing on sleep/wake contrasts, and then the literature on whether any specific factors during sleep preferentially benefit emotional memories, with a special focus on the often-suggested claim that rapid eye movement sleep primarily consolidates emotional memories. A second aim was to examine if sleep preferentially benefits memories based on other cues of future relevance such as reward, test-expectancy or different instructions during encoding. Once again, we first focused on studies comparing sleep and wake groups, and then on studies examining the contributions of specific factors during sleep (for each future relevance paradigm, respectively). The review revealed that although some support exists that sleep is more beneficial for certain kinds of memories based on emotion or other cues of future relevance, the majority of studies does not support such an effect. Regarding specific factors during sleep, our review revealed that no sleep variable has reliably been found to be specifically associated with the consolidation of certain kinds of memories over others based on emotion or other cues of future relevance.

It has been proposed that sleep readies the brain for novel learning, and previous work has shown that sleep loss impairs the ability to encode new memories. In the present study, we examined if a daytime nap would increase mnemonic discrimination (MD) performance. MD is the ability to differentiate between memories that are similar but not identical. Participants performed the Mnemonic Similarity Task (MST) twice, once in the morning and once in the afternoon. The goal of this task is to distinguish stimuli that have been seen before from novel stimuli that are similar but not identical. After the morning MST, participants were randomly allocated into either a sleep or a wake group. The sleep group had a 2-hr nap opportunity, whereas the wake group spent a similar amount of time passively resting. All participants then performed a second MST in the afternoon with a novel set of images. Results did not show any support for increased MD ability after a nap. There was, however, a correlation showing that an increase in sleepiness between sessions predicted a decrease in MD performance. Future work must systematically examine how strong sleep manipulations that are needed for sleep to have an effect on encoding ability, as well as which kind of memory tasks that are sensitive to sleep manipulations. More knowledge about the relationship between sleep and the ability to differentiate similar memories from each other is important because impaired MD ability has previously been reported in various groups in which sleep disturbances are also common.

Objectives: Sleep has been shown to be involved both in emotion regulation and in the active processing of information. We combined these two concepts and tested if sleep affected the generalization of fear learning.

Methods: In a fear conditioning paradigm, participants were shown images of a small and a big circle where one of them was paired with an aversive sound, making it the CS+. Fear was measured with skin conductance responses. Participants were then randomly divided into a sleep or a wake group. The sleep group took a 2 h nap while the wake group rested for 2 h. Participants were then exposed to the two circles seen before, combined with 8 novel circles that gradually varied in size from the small one to the big one. We looked at how many circle sizes away from the CS+ that participants still exhibited a fear response, and if this differed between the sleep and the wake group.

Results: We found no effect of sleep on the slope of the generalization across the different circles. There was a main effect of circle size, F(1,25) = 10.42, P = 0.01, but no main effect of sleep/wake, F (1,25) = 0.40, P = 0.54, and no interaction between sleep/wake X circle size, F(1,25) = 0.62, P = 0.44.

Conclusions: The fear conditioning manipulation worked, with a gradual increase of fear depending on the stimuli’s similarity to the CS+. However, there was no effect of sleep or wake, which could possibly be explained by that just a 2 h nap not being a sufficient sleep manipulation to detect any differences.

It has long been established, that views to natural scenes can a have a dampening effect on physiological stress responses. However, as people in Europe, Canada and North America today spent 50-85% of their time indoors, attention might also be paid to how the artificial man-made indoor environment influences these mechanisms. The question that this study attempts to start addressing is therefore whether certain design, characteristics of indoor spaces can make a difference to the physiological stress response as well. Using a virtual version of the Trier Social Stress Test, in which the space is computer generated and properties of the space therefore can be systematically varied, we measured saliva cortisol and heart rate variability in participants in a closed room versus a room with openings. As shown by a significant linear contrast interaction between groups and TSST conditions, participants in the closed room responded with more pronounced cortisol reactivity to stress induction, and continued to show higher levels throughout recovery, compared to participants in the open room. No differences were found regarding any part of the autonomic nervous system.

In this paper, the results of different multiple window spectrum analysis methods are compared in the estimation of heart rate variability (HRV) power spectra, in the high frequency band (HF), around 0.25 Hz, related to respiratory sinus arrhythmia (RSA). The evaluation is performed by simulating different spectrum shapes and peak frequency locations and calculating the mean squared error of a frequency range close around the strongest spectral peak. The results show that it is preferable to use the Peak Matched Multiple Windows in most situations, but the Welch method and the Sinusoid Multiple Windows can be as reliable in certain aspects.

In this paper, we evaluate the correlation estimate, based on multiple window spectrum analysis, between the respiratory center frequency and the high-frequency band of the heartrate variability (HRV) power. One aim is to examine whether a more restricted frequency range would better capture respiratory related HR variation, especially when the HR variation is changing rapidly. The respiratory peak is detected and a narrow-banded measure of the high-frequency (HF) band of the HRV is defined as the respiratory frequency +/-0.05 Hz. We compare the mean square error of the correlation estimate between the frequency of the respiratory peak and the power of the HRV with the power in the usual 0.12-0.4 Hz frequency band. Different multiple window spectrum techniques are used for the estimation of the respiratory frequency as well as for the power of the HRV. We compare the peak-matched multiple windows with the Welch method while evaluating the two different HF-power estimates mentioned above. The results show that using a more narrow band for the power estimation gives stronger correlation which indicates that the estimate of the power is more robust.

Respiratory sinus arrhythmia (RSA) was examined in relation to state and trait anxiety in healthy individuals. Time-frequency analyses of HR-power spectrum in the high frequency region (0.12-0.40 Hz), related to RSA, were examined in 43 women and 39 men. Based on median split, the participants were divided into high and low state and trait anxiety groups. The main result showed that high state anxious individuals had higher RSA-magnitude (HF-power) than low state anxious individuals. The higher RSA-magnitude in the former group was interpreted as reflecting increased attention or vigilance together with motor and behavioural inhibition. No significant effects of trait anxiety or gender were found.

The relationship between creativity and androgyny was studied in 163 women and men with the Creative Functioning Test (CFT) and the Bem Sex Role Inventory (BSRI). A 2 (femininity: high/low) x 2 (masculinity: high/low) x 2 (sex) ANOVA was conducted on subjects' CFT scores. A significant interaction effect between femininity and masculinity was found showing that subjects high on both femininity and masculinity (androgynous) and low on both scales (undifferentiated) reached higher CFT scores than female-typed and male-typed subjects. Further, a significant three-way interaction including sex of subject indicated that the former two-way interaction was accounted for by men only.

Heart period variability and heart rate were studied in 15 women and 15 men while they were viewing negatively (snakes/spiders), neutrally (scenic views), and positively (cats and kittens/puppies and dogs) valenced films. Time-frequency analyses of the heart period variability power spectrum in the high frequency region (0.12-0.4 Hz), reflecting respiratory sinus arrhythmia (RSA), were carried out during 5 minutes in each condition. The main finding showed that RSA-magnitude (high frequency power) was inversely related to emotional valence: lowest magnitudes were found in response to positive films, and highest magnitude to negative films. The findings were interpreted as reflecting motor or behavioral inhibition, and increased attention to negatively valenced, stimuli.

The aim of the present study was to examine autonomic function in response to negatively and positively valenced pictures under different levels of conscious recognition. Heart period variability (HPV) and heart rate (HR) reactivity were studied in 53 males and females who were being shown pictures of angry and happy faces. The pictures, which were backwardly masked, were presented once every 30 s during a 5-min period and under three conditions (counterbalanced for type of facial expression): below the level of conscious recognition (17 ms), at an intermediate level (56 ms), and at a clearly recognizable level (2370 ms). Analyses of HR power spectrum (for 5 min in each condition) in the high frequency region (HF: 0.15-0.5 Hz) that reflects respiratory sinus arrhythmia, as well as analysis of phasic heart rate responses (7.5 s in 0.5 epochs following every picture presentation) were carried out. The main findings were that HF-power was higher, and cardiac midinterval acceleration lower, in response to angry as opposed to happy faces, a result obtained only for the men, however. No interaction effect between facial expression and the three exposure conditions was found, suggesting that the pictures induced emotional activation both subliminally and supraliminally. The results were discussed in terms of increased attention to aversive stimuli.

The Trier Social Stress Test (TSST) is a widely used protocol to induce stress in laboratory settings. Briefly, in the TSST, the test participant is asked to hold a speech and to do an arithmetic task in front of an audience. In the present pilot study, we examined endocrine and autonomic reactivity and habituation to repeated stress provocations using a virtual reality (VR) version of TSST. The VR system was a CAVE™ system with three rear projected walls (4 m×3 m), and one floor projection. The system also included a head tracking system and passive stereoscopy. The virtual audience consisted of one woman, and two men. Ten healthy men, mean age 28.3 years (24-38 years), were confronted with the test twice (1 week between sessions), during which salivary cortisol, heart rate (HR), high frequency heart rate variability (HF-HRV, parasympathetic activity), and T-wave amplitude (TWA, suggested to be related to sympathetic influence on myocardial performance) were assessed. Cortisol secretion showed a marked increase (88% vs. baseline) during the first stress provocation, but habituated in the second session. The magnitude of HR and TWA reactivity during stress provocation was approximately the same at both sessions, implying a stable increase in sympathetic activity. Heart rate showed a maximum increase of 40% at the first session, and 32% at the second. TWA showed a maximum decrease of 42% at the first session, and 39% at the second. The results resemble those obtained in prior studies using the real-life TSST. If these results can be replicated with larger samples, VR technology may be used as a simple and standardized tool for social stress induction in experimental settings.

Aim

In two previous studies we report that subjective ratings of state anxiety in healthy individuals co-vary positively with vagally mediated high frequency heart rate variability (HF-HRV), during base line recording before an experimental task, and during social stress induction. In this pilot study cardiovascular regulation was examined during a stressful task in high-, and low trait anxious individuals.

Method

35 healthy men were divided in to one high- and one low-anxiety group based on the median split of the results of the Spielberger Trait Anxiety Inventory (M = 39.9, SD = 8.5, resp. M = 26.2, SD = 3.3, p < .001). Both groups were confronted with a virtual version of the Tier Social Stress Test (V-TSST), involving two tasks: to hold a speech, and to complete a mathematical task in front of a committee. Heart rate (HR), high frequency HR variability (HF-HRV, related to vagal activity), T-wave amplitude (TWA, inversely related to sympathetic activity) and respiration were assessed before, during, and after the V-TSST.

Results

Main effects showed that during stress HR increased [F(7, 231) = 63.98, p < .001, η2 = .66], TWA decreased [F(7, 231) = 33.69, p < .001, η2 = .51]. Regarding HF-HRV an interaction with trait anxiety was found [F(7, 231) = 2.83, p = .047, η2 = .08; cubic F(1, 33) = 5.51, p = .025, η2 = .14], indicating slightly higher magnitudes during stress for the high anxious group, but lower magnitudes for the low anxious group.

Discussion

Both anxious groups responded with increased HR and sympathetic activity (decreased TWA) during V-TSST. However, the high anxious group showed higher HF-HRV during stress than the low anxious group. Tentatively, the participants with higher trait anxiety activate the vagal system to inhibit the sympathetic system to adequately cope with the stressful situation in order to complete the tasks successfully. It is important, however, to note that the high anxious group doesn’t represent a clinical sample. Clinical anxiety is generally associated with reduced HF-HRV suggested partly being related to poor emotional and attentional control. Healthy individuals with moderate increases in trait anxiety, on the other hand, would likely have a well functioning vagal system to engage in attention demanding and stressful tasks.

Prior findings indicate that individuals scoring high on vital exhaustion show a dysfunctional stress response (DSR), that is, reduced cortisol reactivity and habituation to psychosocial stressors. The main aim of the present study was to examine whether a DSR may be a vulnerability factor in exhaustion disorder (ED). We examined whether a DSR is present during early stages of ED, and still is present after recovery. Three groups were studied: 1. Former ED patients (n=14); 2. Persons who during the past 6 month had experienced stress at work and had a Shirom-Melamed Burnout Questionnaire (SMBQ) score over 3.75, considered to indicate a pre-stage of ED (n=17); 3. Persons who had not experienced stress at work during the past 6 months and had a SMBQ score below 2.75 (n=20). The participants were exposed twice to a virtual version of Trier Social Stress Test (V-TSST), during which salivary cortisol samples were collected. In addition, high frequency heart rate variability (HF-HRV), heart rate (HR), t-wave amplitude (TWA), and α-amylase were assessed to examine stress reactivity and habituation in the autonomic nervous system (ANS). The initial analyses showed clear hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) activations in both V-TSST sessions, together with habituation of cortisol and heart rate in the second session, but without any significant group differences. However, the former ED patients showed considerable variation in self-reported signs of exhaustion (SMBQ). This led us to assign former ED patients with lower ratings into the low SMBQ group (LOWS) and those with higher ratings to the high SMBQ group (HIGHS). When repeating the analyses a different picture emerged; the HIGHS showed a lower cortisol response to the V-TSST than did the LOWS. Both groups' cortisol response habituated to the second V-TSST session. The ANS responses did not differ between the two groups. Thus, persons in a pre-stage of ED and unrecovered former ED patients showed signs of DSR, in contrast to healthy controls and recovered former ED patients. The results may be interpreted as indicating that DSR in the HPA axis is present early on in the stress process, but subsides after successful recovery.

BACKGROUND: The period from the mid-1990s to the mid-2000s saw a rapid increase in long-term sick leave in Sweden, primarily due to mental illness and often related to job burnout. This led to an urge for effective treatment programs that could prevent the often long sick leaves. In 2010 we presented a newly developed work-place intervention method, showing that 89% of the intervention group had returned to work at a 1.5 year follow-up, compared to 73% of the control group. The main aim of this study was to assess the long-term stability of these promising results.

METHODS: Sick leave registry data from the Regional Social Insurance Office were analyzed for an additional year (50 weeks) beyond the original 1.5 year period (80 weeks). Data from 68 matched pairs of intervention participants (IP) and controls were available. The proportions of participants being on full-time sick leave versus having returned to work to any extent were computed for every 10th week. Generalized estimating equations were used with GROUP (IP versus controls) as between-subjects factor, WEEKS and AGE as covariates, and return-to-work (RTW) as dependent variable. Significant differences (Wald χ2 with α ≤ .05) was followed up with polynomial contrasts. Individual relapses to higher degrees of sick leave (e.g. from 50% to 100%) and whether partial RTW led to later full-time RTW, were also analyzed.

RESULTS: The omnibus test over all 130 weeks showed a GROUP*WEEKS interaction effect (p = .02), indicating differential group developments in RTW, though similarly high at week 130 in both groups with 82.4% of the IP and 77.9% of the controls having RTW (p = .22; χ2-test). A significant interaction with age led to separate analyses of the younger and older subgroups, indicating a stable pattern of superior RTW only among younger IP (week 130: 88.6% vs. 69.7%, p = .054; χ2-test). There was no group difference in relapses into increased degree of sick leave. Part-time sick leave did not predict a later stable full-time RTW.

CONCLUSIONS: The previously reported improvement in RTW with the newly developed workplace-oriented intervention showed a long-term stability only among younger participants.

BACKGROUND: In the present study the effect of a workplace-oriented intervention for persons on long-term sick leave for clinical burnout, aimed at facilitating return to work (RTW) by job-person match through patient-supervisor communication, was evaluated. We hypothesised that the intervention group would show a more successful RTW than a control group.

METHODS: In a prospective controlled study, subjects were identified by the regional social insurance office 2-6 months after the first day on sick leave. The intervention group (n = 74) was compared to a control group who had declined participation, being matched by length of sick leave (n = 74). The RTW was followed up, using sick-listing register data, until 1.5 years after the time of intervention.

RESULTS: There was a linear increase of RTW in the intervention group during the 1.5-year follow-up period, and 89% of subjects had returned to work to some extent at the end of the follow-up period. The increase in RTW in the control group came to a halt after six months, and only 73% had returned to work to some extent at the end of the 1.5-year follow-up.

CONCLUSIONS: We conclude that the present study demonstrated an improvement of long-term RTW after a workplace-oriented intervention for patients on long-term sick leave due to burnout.

TRIAL REGISTRATION: Current Controlled Trials NCT01039168.

BACKGROUND:

The period from the mid-1990s to the mid-2000s saw a rapid increase in long-term sick leave in Sweden, primarily due to mental illness and often related to job burnout. This led to an urge for effective treatment programs that could prevent the often long sick leaves. In 2010 we presented a newly developed work-place intervention method, showing that 89% of the intervention group had returned to work at a 1.5 year follow-up, compared to 73% of the control group. The main aim of this study was to assess the long-term stability of these promising results.

METHODS:

Sick leave registry data from the Regional Social Insurance Office were analyzed for an additional year (50 weeks) beyond the original 1.5 year period (80 weeks). Data from 68 matched pairs of intervention participants (IP) and controls were available. The proportions of participants being on full-time sick leave versus having returned to work to any extent were computed for every 10th week. Generalized estimating equations were used with GROUP (IP versus controls) as between-subjects factor, WEEKS and AGE as covariates, and return-to-work (RTW) as dependent variable. Significant differences (Wald χ2 with α ≤ .05) was followed up with polynomial contrasts. Individual relapses to higher degrees of sick leave (e.g. from 50% to 100%) and whether partial RTW led to later full-time RTW, were also analyzed.

RESULTS:

The omnibus test over all 130 weeks showed a GROUP*WEEKS interaction effect (p = .02), indicating differential group developments in RTW, though similarly high at week 130 in both groups with 82.4% of the IP and 77.9% of the controls having RTW (p = .22; χ2-test). A significant interaction with age led to separate analyses of the younger and older subgroups, indicating a stable pattern of superior RTW only among younger IP (week 130: 88.6% vs. 69.7%, p = .054; χ2-test). There was no group difference in relapses into increased degree of sick leave. Part-time sick leave did not predict a later stable full-time RTW.

CONCLUSIONS:

The previously reported improvement in RTW with the newly developed workplace-oriented intervention showed a long-term stability only among younger participants.

The instantaneous frequency (IF) of a non-stationary signal is usually estimated from a time-frequency distribution (TFD). The IF of heart rate variability (HRV) is an important parameter because the power in a frequency band around the IF can be used for the interpretation and analysis of the respiratory rate but also for a more accurate analysis of heart rate (HR) signals. In this study, we compare the performance of five states of the art kernel-based time-frequency distributions (TFDs) in terms of their ability to accurately estimate the IF of HR signals. The selected TFDs include three widely used fixed kernel methods: the modified B distribution, the S-method and the spectrogram; and two adaptive kernel methods: the adaptive optimal kernel TFD and the recently developed adaptive directional TFD. The IF of the respiratory signal, which is usually easier to estimate as the respiratory signal is a mono-component with small amplitude variations with time, is used as a reference to examine the accuracy of the HRV IF estimates. Experimental results indicate that the most reliable estimates are obtained using the adaptive directional TFD in comparison to other commonly used methods such as the adaptive optimal kernel TFD and the modified B distribution.

The virtual version of the Trier Social Stress Test (V-TSST) is an effective and standardized tool for social stress induction. This study aimed to examine gut permeability and physiological and inflammatory markers of reactivity to acute psychosocial stress. Forty young men were classified as high-stressed (HIGHS) or low-stressed (LOWS) according to the Shirom-Melamed Burnout Questionnaire. Cardiovascular reactivity and gut dysfunction were studied along with cortisol, zonulin and cytokines. Gut permeability was shown to be affected within one hour after the psychosocial stress induction, and shown to be dependent on age. Interleukin-6 increased with time, most pronounced at the end of the one-hour recovery after V-TSST, and was positively correlated to age. HIGHS experienced more abdominal dysfunction compared to LOWS. In conclusion, this study is the first to show fluctuations in gut permeability after psychosocial stress induction. This was partly associated with changes in inflammatory markers.

Background: The need for instruments that can assist in detecting the prodromal stages of stress-related exhaustion has been acknowledged. The aim of the present study was to evaluate whether the Lund University Checklist for Incipient Exhaustion (LUCIE) could accurately and prospectively detect the onset of incipient exhaustion and to what extent work stressor exposure and private burdens were associated with increasing LUCIE scores. Methods: Using surveys, 1355 employees were followed for 11 quarters. Participants with prospectively elevated LUCIE scores were targeted by three algorithms entailing 4 quarters: (1) abrupt onset to a sustained Stress Warning (n = 18), (2) gradual onset to a sustained Stress Warning (n = 42), and (3) sustained Exhaustion Warning (n = 36). The targeted participants' survey reports on changes in work situation and private life during the fulfillment of any algorithm criteria were analyzed, together with the interview data. Participants untargeted by the algorithms constituted a control group (n = 745). Results: Eighty-seven percent of participants fulfilling any LUCIE algorithm criteria (LUCIE indication cases) rated a negative change in their work situation during the 4 quarters, compared to 48 % of controls. Ratings of negative changes in private life were also more common in the LUCIE indication groups than among controls (58 % vs. 29 %), but free-text commentaries revealed that almost half of the ratings in the LUCIE indication groups were due to work-to-family conflicts and health problems caused by excessive workload, assigned more properly to work-related negative changes. When excluding the themes related to work-stress-related private life compromises, negative private life changes in the LUCIE indication groups dropped from 58 to 32 %, while only a negligible drop from 29 to 26 % was observed among controls. In retrospective interviews, 79 % of the LUCIE indication participants confirmed exclusively/predominantly work stressors, while 6 % described a predominance of private life stressors. Conclusions: Negative changes in the work situation were the most prominent change related to a sustained increase in LUCIE scores. The findings seem to confirm that LUCIE is a potentially useful tool for clinical screening of incipient work-related exhaustion.

BACKGROUND: Stress-related health problems (e.g., work-related exhaustion) are a societal concern in many postindustrial countries. Experience suggests that early detection and intervention are crucial in preventing long-term negative consequences. In the present study, we benchmark a new tool for early identification of work-related exhaustion-the Lund University Checklist for Incipient Exhaustion (LUCIE)-against other contextually relevant inventories and two contemporary Swedish screening scales.

METHODS: A cross-sectional population sample (n = 1355) completed: LUCIE, Karolinska Exhaustion Disorder Scale (KEDS), Self-reported Exhaustion Disorder Scale (s-ED), Shirom-Melamed Burnout Questionnaire (SMBQ), Utrecht Work Engagement Scale (UWES-9), Job Content Questionnaire (JCQ), Big Five Inventory (BFI), and items concerning work-family interference and stress in private life.

RESULTS: Increasing signs of exhaustion on LUCIE were positively associated with signs of exhaustion on KEDS and s-ED. The prevalence rates were 13.4, 13.8 and 7.8 %, respectively (3.8 % were identified by all three instruments). Increasing signs of exhaustion on LUCIE were also positively associated with reports of burnout, job demands, stress in private life, family-to-work interference and neuroticism as well as negatively associated with reports of job control, job support and work engagement.

CONCLUSIONS: LUCIE, which is intended to detect pre-stages of ED, exhibits logical and coherent positive relations with KEDS and s-ED as well as other conceptually similar inventories. The results suggest that LUCIE has the potential to detect mild states of exhaustion (possibly representing pre-stages to ED) that if not brought to the attention of the healthcare system and treated, may develop in to ED. The prospective validity remains to be evaluated.

AIMS: To examine the relationships of two screening instruments recently developed for assessment of exhaustion disorder (ED) with some other well-known inventories intended to assess ED-related concepts and self-reports of job demands, job control, job support, private life stressors, and personality factors.

METHODS: A cross-sectional population sample ( n = 1355) completed: the Karolinska Exhaustion Disorder Scale (KEDS), Self-reported Exhaustion Disorder Scale (s-ED), Shirom-Melamed Burnout Questionnaire (SMBQ), Utrecht Work Engagement Scale (UWES-9), Job Content Questionnaire (JCQ), Big Five Inventory (BFI), and items concerning family-to-work interference and stress in private life.

RESULTS: Compared to participants without any indication of ED, participants classified as having ED on KEDS or s-ED had higher scores on all four SMBQ subscales, lower scores on the UWES-9 subscales vigor and dedication, higher JCQ job demands scores, lower JCQ job support scores, higher degrees of family-to-work interference and stress in private life, and higher BFI neuroticism and openness scores. In addition, participants classified as having ED on KEDS had lower scores on the UWES-9 absorption subscale, the JCQ job control scale, and lower BFI extraversion, agreeableness and conscientiousness scores, compared to the subgroup not classified as having ED.

CONCLUSIONS: As expected, we observed an overall pattern of associations between the ED screening inventories KEDS and s-ED and measures of burnout, work engagement, job demands-control-support, stress in private life, family-to-work interference, and personality factors. The results suggest that instruments designed to assess burnout, work engagement, and ED share common ground, despite their conceptual differences.

Individuals with a dismissing-avoidant pattern of attachment are assumed to repress anxiety-related signals, a disposition hypothesized to interfere with facial mimicry and emotional contagion. Further, they are assumed to have one internal working model associated with anxiety, operating out of awareness at early, automatic stages of information processing, and another positive model operating at later, cognitively controlled stages of processing. The main aim of the present investigation was to compare facial mimicry in dismissing-avoidant and non-dismissing subjects at different levels of information processing. Pictures of happy and angry faces were exposed to 61 subjects at three different exposure times (17, 56, and 2,350 ms) in order to elicit facial muscle reactions, first at automatic levels and then at a more controlled levels. Corrugator activity ("frowning muscles") represented negative emotions and zygomaticus activity ("smiling muscles") positive emotions. The dismissing-avoidant subjects scored significantly lower on emotional empathy than the non-dismissing subjects. At the automatic level the dismissing-avoidant subjects showed "normal" corrugator responses (negative emotions) upon exposure to angry faces. At the cognitively controlled level of processing (2,350 ms) a significant interaction effect was shown between Faces x Muscles x Attachment pattern. The dismissing-avoidant subjects showed no corrugator response and an increased zygomaticus response ("smiling reaction") to the angry face, whereas the non-dismissing subjects reacted with a significant mimicking reaction. The dismissing-avoidant subjects' tendency to "smiling" in response to the angry face at the controlled level (2,350 ms) may be interpreted as a repression of their earlier, automatically evoked (56 ms) negative emotional reaction.

The hypotheses of this investigation were based on attachment theory and Bowlby's conception of "internal working models", supposed to consist of one mainly emotional (model-of-self) and one more conscious cognitive structure (model-of-others), which are assumed to operate at different temporal stages of information processing. Facial muscle reactions in individuals with positive versus negative internal working models were compared at different stages of information processing. The Relationship Scale Questionnaire (RSQ) was used to categorize subjects into positive or negative model-of-self and model-of-others and the State-Trait Anxiety Inventory was used to measure trait anxiety (STAI-T). Pictures of happy and angry faces followed by backward masking stimuli were exposed to 61 subjects at three different exposure times (17 ms, 56 ms, 2,350 ms) in order to elicit reactions first at an automatic level and then consecutively at more cognitively elaborated levels. Facial muscle reactions were recorded by electromyography (EMG), a higher corrugator activity representing more negative emotions and a higher zygomaticus activity more positive emotions. In line with the hypothesis, subjects with a negative model-of-self scored significantly higher on STAI-T than subjects with a positive model-of-self. They also showed an overall stronger corrugator than zygomatic activity, giving further evidence of a negative tonic affective state. At the longest exposure time (2,350 ms), representing emotionally regulated responses, negative model-of-self subjects showed a significantly stronger corrugator response and reported more negative feelings than subjects with a positive model-of-self. These results supported the hypothesis that subjects with a negative model-of-self would show difficulties in self-regulation of negative affect. In line with expectations, model-of-others, assumed to represent mainly knowledge structures, did not interact with the physiological emotional measures employed, facial muscle reactions or tonic affective state.

The hypotheses of this investigation were based on conceiving of facial mimicry reactions in face-to-face interactions as an early automatic component in the process of emotional empathy. Differences between individuals high and low in emotional empathy were investigated. The parameters compared were facial mimicry reactions, as represented by electromyographic (EMG) activity, when individuals were exposed to pictures of angry or happy faces. The present study distinguished between spontaneous facial reactions and facial expressions associated with more controlled or modulated emotions at different information processing levels, first at a preattentive level and then consecutively at more consciously controlled levels: 61 participants were exposed to pictures at three different exposure times (17, 56, and 2350 ms). A significant difference in facial mimicry reactions between high- and low-empathy participants emerged at short exposure times (56 ms), representing automatic, spontaneous reactions, with high-empathy participants showing a significant mimicking reaction. The low-empathy participants did not display mimicking at any exposure time. On the contrary, the low-empathy participants showed, in response to angry faces, a tendency to an elevated activation in the cheek region, which often is associated with smiling.

Previous studies on gender differences in facial imitation and verbally reported emotional contagion have investigated emotional responses to pictures of facial expressions at supraliminal exposure times. The aim of the present study was to investigate how gender differences are related to different exposure times, representing information processing levels from subliminal (spontaneous) to supraliminal (emotionally regulated). Further, the study aimed at exploring correlations between verbally reported emotional contagion and facial responses for men and women. Masked pictures of angry, happy and sad facial expressions were presented to 102 participants (51 men) at exposure times from subliminal (23 ms) to clearly supraliminal (2500 ms). Myoelectric activity (EMG) from the corrugator and the zygomaticus was measured and the participants reported their hedonic tone (verbally reported emotional contagion) after stimulus exposures. The results showed an effect of exposure time on gender differences in facial responses as well as in verbally reported emotional contagion. Women amplified imitative responses towards happy vs. angry faces and verbally reported emotional contagion with prolonged exposure times, whereas men did not. No gender differences were detected at the subliminal or borderliminal exposure times, but at the supraliminal exposure gender differences were found in imitation as well as in verbally reported emotional contagion. Women showed correspondence between their facial responses and their verbally reported emotional contagion to a greater extent than men. The results were interpreted in terms of gender differences in emotion regulation, rather than as differences in biologically prepared emotional reactivity.

The first aim of the study was to investigate whether facial imitative responses and subjective experiences of emotional contagion (self-reported hedonic tone) can be evoked as a result of unconscious information processing or whether these responses rely on conscious, interpretative processing. As a second aim, the correspondence between the participants’ self-reported hedonic tone and the magnitude of their facial responses was investigated. The third aim was to explore how increased involvement of conscious processing (longer exposure times) influenced facial imitative responses, self-reported hedonic tone, and the correspondence between these responses. Information-processing levels from unconscious (17–23 ms) to conscious (2,500 ms) levels were induced by successively prolonged presentations of facial stimuli. The 102 participants were exposed to masked pictures of happy, angry, and sad facial expressions. Facial responses (EMG) and self-reports of hedonic tone were measured after facial stimuli exposures. Verbally reported emotional contagion and zygomaticus imitative responses were observed at the subliminal exposure level, as well as correlations between these responses. These results were interpreted as being in line with a spontaneous, unconscious process involved in imitation and the subjective experiences of emotional contagion. Correlations between the participants’ magnitude of facial responses and their degree of emotional contagion were found at all exposure levels, from subliminal to clearly supraliminal levels of exposure. At the supraliminal exposure, 26 of the participants responded with inverted zygomaticus responses (“smiles”) toward angry expressions, a response that may be interpreted as a defensive response.

One of the most common methods of inducing stress in the laboratory in order to examine the stress response in healthy and clinical populations is the Trier Social Stress Test (TSST). Briefly, the participant is asked to deliver a speech and to perform an arithmetic task in front of an evaluating committee. The committee, consisting of three trained actors, does not respond emotionally during the test, which makes the situation very stressful for the participant. One disadvantage of the TSST is that it can be difficult to hold the experimental conditions constant. In particular, it may be difficult for actors to hold their acting constant across all sessions. Furthermore, there are several practical problems and costs associated with hiring professional actors. A computerized version of the TSST using virtual humans could be a way to avoid these problems provided that it is able to induce a stress response similar to the one of the original TSST. The purpose of the present pilot study was therefore to investigate the stress response to a virtual reality (VR) version of the TSST visualized using an immersive VR system (VR-TSST). Seven healthy males with an average age of 24 years (range: 23-26 years) performed the VR-TSST. This included delivering a speech and performing an arithmetic task in front of an evaluating committee consisting of three virtual humans. The VR equipment was a CAVE equipped with stereoscopy and head tracking. ECG and respiration were recorded as well as the participant's behavior and comments. Afterward, a semi-structured interview was carried out. In general, the subjective and physiological data from the experiment indicated that the VR version of the TSST induced a stress response in the seven participants. In particular, the peak increase in heart rate was close to rates observed in studies using the traditional TSST with real actors. These results suggest that virtual humans visualized with an immersive VR system can be used to induce stress under laboratory conditions.

The aim of this study was to test whether an Implicit Association Test (IAT) with self- and social anxiety-words is sensitive to differences in trait social anxiety, and to an experimental induction of social anxiety. This was performed in the context of a partial replication of a previous study, in which Mauss et al. (2004) compared high and low trait socially anxious individuals before and after a social anxiety induction (an impromptu speech). Mauss et al.'s findings were replicated; that is, (i) the social anxiety induction produced increases in self-rated anxiety, self-rated physiological responses, and actual physiological arousal; and (ii) higher trait social anxiety was associated with stronger self-rated anxiety and stronger self-rated physiological responses, but not with stronger actual physiological responses. In addition, the results showed higher IAT social anxiety scores, both (i) as a result of the social anxiety induction, and (ii) as a function of self-reported trait social anxiety. It is suggested that the IAT may be a useful method for the experimental study of automatic evaluational thought patterns.

The intestine and the brain are connected via the brain-gut axis and the intestinal microbiota influences the immune activation and signaling molecules that are involved in the stress response. The aim of the study was to investigate if intake of the probiotic strain Lactobacillus plantarum HEAL9 (LPHEAL9) for four weeks could counteract elevated cortisol and inflammation levels in subjects with chronic stress that are exposed to an acute stress test (Trier Social Stress Test, TSST). Seventy participants were included, and 63 participants completed the study (LPHEAL9, n=32; placebo, n=31). Cardiovascular reactivity and cortisol levels were affected by the TSST, but no differences between the groups were observed. Intake of LPHEAL9 did, however, result in significantly decreased plasma levels of two inflammatory markers (soluble fractalkine and CD163) compared to placebo. In conclusion, intake of LPHEAL9 for four weeks may reduce inflammatory markers coupled to acute stress in chronically stressed individuals.