High Heart Rate Variability Research Articles

Effect of an eight-week smartphone-guided HRV-biofeedback intervention on autonomic function and impulsivity in healthy controls

A large body of scientific studies suggest a close relationship between increased vagal function and better cognitive performance. Objective: In the current study, we investigated the association between autonomic function and behavioral impulsivity. We hypothesized that heart rate variability (HRV) biofeedback training increases HRV and enhances inhibitory control. Approach: A total of 28 healthy participants were recruited. After drop-out, 14 participants completed an eight-week HRV biofeedback training with five training sessions per week including one session at the clinic’s laboratory and four sessions at home using a mobile application running on their smartphone. Ten control subjects matched with respect to age and gender played a mobile game according to the same schedule as the biofeedback group. The assessment of autonomic status and the stop-signal task were conducted before the beginning of the training (T1) and after finishing the schedule (T2). Main results: We found a relationship of reaction times in the stop-signal task and standard HRV as well as cardiorespiratory indices. After biofeedback training, short-term HRV and baroreflex function significantly increased by 33% (CI [2%, 64%], p < 0.05) and 21% (CI [5%, 36%], p < 0.05), respectively. The performance in the stop-signal task was not affected by the biofeedback intervention. Compared to the changes of autonomic indices in the control group, only a decrease of skin conductance levels in the biofeedback group remained statistically significant. Significance: Our results indicate that a smartphone-based HRV biofeedback intervention can be applied to improve cardiovagal function in healthy subjects. Although higher HRV was associated with higher levels of inhibitory control, HRV biofeedback had no effect on measures of impulsivity.

NCAA Preseason Demonstrates Greatest Impact on Heart Rate Variability, Training Load and Sleep In Men's Soccer

PURPOSE: The purpose of this study was to compare training load (TL), sleep, heart rate variability (HRV) and resting (RHR) by season phase over a full NCAA collegiate men’s soccer season. METHODS:Daily TLs (duration [min], distance covered [m], time spent in heart rate >80 % of the individual’s max [min], number of sprints [n], and distance covered while running >14.4 km·h-1 [m]) were monitored in 31 male NCAA Division 1 male soccer athletes (mean ± SD; age, 20 ± 2 y; body mass, 79.92 ± 6.69 kg; height, 181.48±6.35 cm; VO2max, 50.87 ± 4.38 ml·kg-1·min-1) using GPS-enabled player tracking devices during the Fall 2016 soccer preseason (PRE), regular season (REG), and post-season (POST). Sleep duration (min), sleep efficiency (%), and RHR and HRV z-scores (SD) were tracked using a multi-sensor wrist-worn deviceand a validated self-reported sleep questionnaire (Karolinksa Sleep Diary). Linear mixed effects models with a fixed factor of season phase and a random factor of participant was used. Mean differences (MD) were assessed post-hoc with a Tukey HSD, with alpha set at 0.05 for all analysis. RESULTS: During PRE, participants experienced an increased distance (1527 ± 177 m), time (31 ± 3 min) and sprints (8 ± 1) (all p < 0.001) per session vs. REG, and increased distance (1793 ± 312 m), time (39 ± 6 min) and sprints (9 ± 1) per session vs. POST (all p < 0.001). A decrease in sleep efficiency was observed during PRE vs. REG (MD = -2.00 ± 0.05 %; p = 0.004). Self-reported sleep duration during REG was longer vs. PRE (MD = 45 ± 8 min; p < 0.001) and POST (MD = 32 ± 12 min; p = 0.01). No differences were observed for objective sleep duration or RHR at any point throughout the season (p > 0.05). RHR was found to be lower during PRE vs. REG (MD = -0.16 ± 0.06S D; p = 0.02). Finally, HRV during REG was reduced vs. PRE (MD = -0.14 ± 0.06 SD; p = 0.05). CONCLUSION: This study indicates higher HRV, greater physical and physiological loading, decreased self-reported sleep and decreased sleep efficiency during PRE compared to REG. In this men’s soccer team, PRE training was associated with significantly increased physical stress, adverse sleep characteristics and increased HRV. These responses should be considered when designing and implementing optimal training and recovery strategies.

Does socio-ecology drive differences in alertness between wolves and dogs when resting?

Variation in resting behaviour across animals may be driven by adaptations towards their environment. Wolves and dogs seem promising models to examine this idea as they share a common ancestor, but occupy different socio-ecological niches. While wolves generally avoid humans, hunt, defend their territory, and raise offspring cooperatively, most dogs live in human-shaped environments. Hence, we hypothesized wolves to be more alert towards their environment than dogs, i.e. the degree of activation along the sleep-wake continuum (alertness) should be greater in wolves than in dogs. We estimated alertness via cardiac output. We tested similarly raised and kept pack-living wolves and dogs in two different behavioural conditions: (1) inactive wakefulness: animal is lying, head in an upward position with eyes opened, (2) resting: animal is lying, head in downward position with eyes mainly closed. In contrast to our expectations, we found that in both conditions wolves had a lower heart rate and higher heart rate variability than dogs, i.e. wolves might be less alert/more relaxed than dogs. Although our results are preliminary, we suggest that the higher alertness of dogs compared to wolves is potentially driven by differences in their socio-ecology (i.e. domestication) causing greater attention of dogs to human behaviour.

The association between plasma cholesterol and the effect of tryptophan depletion on heart rate variability.

Studies on the cholesterol-serotonin hypothesis and its link to mood disorders are scarce. In addition, little is known about the association between cholesterol and the effects of tryptophan depletion (TD). The aim of the present study was to investigate the association between plasma cholesterol and changes in heart rate variability (HRV), an important marker of depression and anxiety, after TD. The plasma cholesterol levels of 28 healthy participants were noted, and their HRVs were measured by spectrum analysis. TD was carried out on testing day, and participants provided blood samples just before and 5 hours for tryptophan level after TD. HRV was measured again after TD. An association was found between plasma cholesterol levels and the change in HRV. Decreased high frequency HRV was marginally associated with lower levels of high-density lipoprotein cholesterol, while increased low frequency HRV was significantly associated with lower levels of total and low-density lipoprotein cholesterol. Our findings indicate that low cholesterol levels may play parts of role in the mechanism of the deactivation of parasympathetic, and activation of sympathetic, functions induced by altered serotonergic function.

Heart-Brain Coherence; Heart-Rate Variability (HRV); Reading Anxiety; TestEdge Program

Based on psychophysiological research, coherent heart-brain interaction can change afferent cardiac signal pattern sent to the brain. Accordingly, the present study aimed at facilitating the emotion-cognition interaction through HeartMath Institute self-regulated emotional techniques to investigate the efficacy of heart-brain coherence on reading anxiety reduction that significantly enhances attention, memory, comprehension, and efficiency in learning. Participants were 63 Iranian university and high school students. In order to enable the participants to self-generate high psychophysiological state and optimal heart rate variability (HRV), TestEdge program, a biofeedback remedy that teaches students skills to self-regulate negative emotional learning impediments, was administered. Findings indicated that the combination of intentional heart focus with the generation of sustained positive feelings increased heart-brain coherence and resulted in a beneficial mode of psychophysiological state. This heart-brain coherence affected and controlled the HRV patterns significantly among the participants on average which, in turn, reduced reading anxiety. Particularly, this study found significant differences among the EFL students with high, mid, and low levels of coherence and their reading anxiety level.

Abstract P099: Heart Rate Variability Differences Between Green and Suburban Walking: A Pilot Crossover Study

Introduction: Heart rate variability (HRV) assesses the sympathetic and parasympathetic innervation of the heart. Lower HRV indicates greater sympathetic tone and is associated with adverse cardiovascular outcomes. During exercise, factors like activity intensity influence HRV. Yet, an environment’s inherent anxiety-/stress-promoting characteristics may also affect HRV. Hypothesis: Given nature’s calming characteristics, we hypothesized green (i.e., nature-based) walking would promote higher HRV and less HRV reduction than suburban walking. Methods: Twenty-four middle-aged adults (20 female; 49.3 ± 6.7 yrs; BMI: 30.7 ± 7.9 kg/m 2 ) participated in this nine-week crossover study comprised of once-weekly 50-minute moderate-intensity walking sessions. Participants walked for three weeks in each of two treatment conditions: (1) green walking: nature-based walking on trails of local arboretum; and (2) suburban walking: walking on sidewalks of a local suburb’s downtown area. Half were assigned to suburban walking in the first treatment period, and half completed green walking first. A two-week washout separated treatments. The Zephyr BioHarness 3 assessed HRV—reported as standard deviations of normal-to-normal RR intervals in milliseconds (ms) while also tracking activity intensity. For analysis, walks were split into 15-minute intra-walk phases with the first, second, and third phases representing each walk’s beginning, middle, and end. Five-minute pre- and post-walk sitting phases for HRV were also created. Linear mixed models with repeated measures evaluated HRV phase differences between treatments and HRV change between phases by treatment. Results: Lower HRV was observed during the pre-walk sitting phase in the green (56.5 ms) vs. the suburban walking treatment (62.4 ms; p = 0.04); however, a sequence effect was present ( p = 0.02). Due to lower walking intensity during green walking (0.31 g vs. 0.27 g; p &lt; 0.01), activity intensity was a covariate in all intra-walk analyses. Intra-walk phase analyses revealed higher green vs. suburban walking HRV during the second (29.1 ms vs. 24.2 ms, respectively; p &lt; 0.01) and third (33.9 ms vs. 23.8 ms, respectively; p = 0.03) phases. Further, less HRV reduction was seen between the first and second intra-walk phases during green (-7.6 ms) vs. suburban walking (-12.4 ms; p = 0.05). Between-treatment HRV differences were not found for the post-walk sitting phase. No sequence effects were observed for the intra-walk or post-walk phases. Finally, no carryover effects were observed—suggesting adequate washout between treatments. Conclusions: Green walking elicits higher HRV and less HRV reduction vs. suburban walking. Activity intensity did not explain these observations. Fully powered longer-term trials should rigorously evaluate green walking’s potential anxiety-/stress-reducing characteristics.

Variations in Physiological and Psychological Responses of Orthopaedic Surgeons and Clinical Fellows during Hip and Knee Arthroplasties

Background: Both physical and mental stress is present within the practice of healthcare professionals, which in turn negatively affects the quality of the services provided to the population and therefore, leading to mental exhaustion of the individuals involved. Purpose: To track physiological and psychological responses to common hip and knee surgeries, and during clinic days, in a group of orthopaedic surgeons and their clinical fellows (trainees), and to compare the physiological and psychological results with baseline physiological stress tests. Methods: Heart Rate (HR), Breathing Rate (BR), and self-reported anxiety were recorded in 3 fellowship trained orthopaedic surgeons and 5 clinical fellows using a wearable Equivital EQO2 physiological monitor and the State-Trait Anxiety Inventory (STAI). Data was recorded for days in surgery as well as clinic for 6-8 hours/day. This data was compared to baseline physiological stress tests. Results: Mean HR and percentage of heart rate maximum (%HR-max) were not significantly different between staff and fellows throughout the surgery days regardless of the role occupied during both primary Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA). For Heart rate variability (HRV), there was no difference noted between staff and fellows at any moment around and during THA, however, fellows had significantly higher variability during TKA and maintained this increased variability in the postoperative period. In THA, staff failed to show any statistical difference between the HRV in the cases they were assuming the role of primary surgeon compared to the cases they were assisting and the clinic days. On the contrary, fellows showed significantly higher HRV when they were assisting during THA compared to when they were assuming the primary surgeon role or during their clinic days. Conclusion: Different stress patterns were noted in clinical fellows compared to the staff, especially showing a higher overall HRV during TKA.

Nocturnal heart rate variability moderates the association between sleep-wake regularity and mood in young adults.

Sleep-wake regularity (SWR) is often disrupted in college students and mood disorders are rife at this age. Disrupted SWR can cause repetitive and long-term misalignment between environmental and behavioral cycles and the circadian system which may then have psychological and physical health consequences. We tested whether SWR was independently associated with mood and autonomic function in a healthy adult cohort. We studied 42 college students over a 3 week period using daily sleep-wake diaries and continuous electrocardiogram recordings. Weekly SWR was quantified by the interdaily stability of sleep-wake times (ISSW) and mood was assessed weekly using the Beck Depression Inventory-II. To assess autonomic function, we quantified the high-frequency (HF) power of heart rate variability (HRV). Linear mixed effects models were used to assess the relationship between repeated weekly measures of mood, SWR, and HF. Low weekly ISSW predicted subsequent poor mood and worsening mood independently of age, sex, race, sleep duration, and physical activity. Although no association was found between ISSW and HF, the ISSW-mood association was significantly moderated by nocturnal HF, i.e. reported mood was lowest after a week with low ISSW and high HF. Prior week mood scores did not significantly predict the subsequent week's ISSW. Irregular sleep-wake timing appears to precede poor mood in young adults. Further work is needed to understand the implications of high nocturnal HRV in those with low mood and irregular sleep-wake cycles.

Abstract # 3133 Loneliness and telomere length: Immune and parasympathetic function in a pathway to accelerated aging

Lonely people’s heightened risks for chronic health conditions and early mortality may emerge in part through cellular aging. Lonelier people have more severe responses to acute stress, increasing their risk for herpesvirus reactivation, a possible path to shorter telomeres. Lower parasympathetic activity may modulate this risk. To examine the associations among loneliness, parasympathetic activity, herpesvirus reactivation, and telomere length, 113 healthy men and women ages 40–85 provided blood samples that were assayed for telomere length, as well as the latent herpesviruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV). They also provided heart rate variability (HRV), a measure of parasympathetic activity, and reported on their feelings of loneliness. Lonelier people with lower HRV (i.e., lower parasympathetic activity) had greater CMV reactivation and shorter telomeres compared to their less lonely counterparts, above and beyond demographics, health behaviors, resting heart rate, and social network size. However, loneliness was not associated with viral reactivation or telomere shortening among those with higher HRV. In turn, greater CMV and EBV reactivation was associated with shorter telomeres. Taken together, these data implicate parasympathetic function in a novel route through which loneliness may accelerate cellular aging and hasten mortality.

Heart Rhythm Insights Into Structural Remodeling in Atrial Tissue: Timed Automata Approach.

The heart rhythm of a person following heart transplantation (HTX) is assumed to display an intrinsic cardiac rhythm because it is significantly less influenced by the autonomic nervous system—the main source of heart rate variability in healthy people. Therefore, such a rhythm provides evidence for arrhythmogenic processes developing, usually silently, in the cardiac tissue. A model is proposed to simulate alterations in the cardiac tissue and to observe the effects of these changes on the resulting heart rhythm. The hybrid automata framework used makes it possible to represent reliably and simulate efficiently both the electrophysiology of a cardiac cell and the tissue organization. The curve fitting method used in the design of the hybrid automaton cycle follows the well-recognized physiological phases of the atrial myocyte membrane excitation. Moreover, knowledge of the complex architecture of the right atrium, the ability of the almost free design of intercellular connections makes the automata approach the only one possible. Two particular aspects are investigated: impairment of the impulse transmission between cells and structural changes in intercellular connections. The first aspect models the observed fatigue of cells due to specific cardiac tissue diseases. The second aspect simulates the increase in collagen deposition with aging. Finally, heart rhythms arising from the model are validated with the sinus heart rhythms recorded in HTX patients. The modulation in the impairment of the impulse transmission between cells reveals qualitatively the abnormally high heart rate variability observed in patients living long after HTX.

Predictors of and barriers to adherence in a 16-week randomised controlled trial of Bikram yoga in stressed and sedentary adults

BackgroundBikram yoga may enhance health outcomes in healthy adults and those at risk for chronic disease, however, challenges remain in achieving optimal adherence to this practice. This study investigated factors influencing adherence to a 16-week Bikram yoga intervention in stressed and sedentary adults. MethodsExperimental group participants (n = 29) were instructed to attend 3–5 Bikram yoga classes weekly for 16 weeks. Baseline demographics, behaviours and health measures were investigated as predictors of adherence. Barriers were assessed via documentation of adverse events, and exit survey responses. ResultsParticipants (38.2 ± 10.1 years) were predominantly overweight-obese (83%), female (79%), and attended 27 ± 18 classes. Higher adherence was associated with older age (p = 0.094), less pain (p = 0.011), fewer physical limitations (p = 0.011), poorer blood lipid profile, and higher heart rate variability (HRV; total power, (p = 0.097)). In multi-variable analysis, three variables: age (β = 0.492, p = 0.006), HRV (β = 0.413, p = 0.021) and pain (β = 0.329, p = 0.048) remained predictors of adherence. Difficulty committing to the trial, lack of enjoyment and adverse events were barriers to adherence. ConclusionsThese findings should be considered in the development of future Bikram yoga trials to facilitate higher levels of adherence, which may enhance health outcomes and inform community practice. Future trials should investigate and address additional barriers and facilitators of Bikram yoga practice.

The effects of device-guided paced breathing on arterial stiffness: Impact of the autonomic nervous system

ObjectiveThe autonomic nervous system (ANS) plays an important role in regulating blood pressure (BP), but its action on arterial stiffness (AS) is still debated. Here we examine if device-guided paced breathing (DGB) 1, via its action on ANS, can affect AS beyond its BP-lowering effect in hypertensive (HT) subjects.Design and MethodsCentral mean arterial pressure (MAP) (pulse-wave analysis of the radial artery, SphygmoCor, AtCor Medical, Australia), AS (carotidfemoral pulse wave velocity (cfPWV), SphygmoCor) and ANS activity (as high resolution heart rate variability (HRV) of low-frequency/high-frequency range (LF/HF)), (Schiller Medilog AR12plus, United States) were determined in HT subjects. All measurements were performed in supine position after 15 min of rest and subsequently repeated during supervised DGB therapy.Results33 HT patients (18 male); age (mean ±SD) 46 ± 13 years; BP 144 ± 19/86 ± 9 mmHg; cfPWV 9.9 ± 2.1 m/s were recruited. DGB decreased (mean [95% CI]) LF/HF by 0.15 [0.08, 0.22] as well as MAP (−6.7 [−8.4,−5.1] mmHg) and cfPWV (−1.1 [−0.8,−1.3] m/s), all P < 0.01. Bivariate analysis showed a positive correlation between decrease in HRV activity and reduction of cfPWV and MAP (ß = 0.476 and ß = 0.402 respectively, both P < 0.05). The relationship between cfPWV and HRV activity was also still significant in multi-regression models adjusted for confounders (baseline PWV value and change in BP), P < 0.05.ConclusionsDGB, via its action on ANS, affected both BP and AS in HT subjects. Reduction of cfPWV was not fully explained by the BP-lowering effect suggesting that the ANS may play an independent role in modulating AS.

The Value of 16-cm Wide-Detector Computed Tomography in Coronary Computed Tomography Angiography for Patients With High Heart Rate Variability.

The aim of this study was to investigate radiation dose and image quality of coronary computed tomography (CT) angiography (CCTA) for patients with high heart rate variability (HRv) using 16-cm wide-detector CT scanner. One hundred sixty-six patients with uncontrolled heart rate underwent CCTA on a 16-cm wide-detector CT system and were divided into 2 groups based on their HRv for analysis: group A (n = 95, HRv ≤10 beats/min [bpm]) and group B (n = 71, HRv >10 bpm). Images in both groups were reconstructed with motion correction algorithm. Subjective and objective image qualities were analyzed. There were no significant differences in age, body mass index, and heart rate (68.1 ± 11.4 vs 67.6 ± 12.3 bpm) between the 2 groups (P > 0.05). However, group B had significantly higher HRv than group A (33.5 ± 24.4 vs 7.8 ± 1.2 bpm, P < 0.001). All images were acceptable for clinical diagnosis. Compared with group A, image quality scores in group B decreased slightly (4.1 ± 0.5 vs 4.0 ± 0.6). However, the difference was not statistically significant. The mean effective doses were both relatively low at 2.2 ± 1.1 mSv in group A and 2.6 ± 1.4 mSv in group B. Single-heartbeat free-breathing CCTA can be performed for patients with high HRv using 16-cm wide-detector CT scanner to achieve diagnostic image quality with low radiation dose.

Aging Alters the Relative Contributions of the Sympathetic and Parasympathetic Nervous System to Blood Pressure Control in Women.

Autonomic support of blood pressure increases with age in humans. Large differences exist in the dose of trimethaphan (TMP) required for ganglionic blockade in young and older women. We asked whether differences in the dose of TMP required to achieve ganglionic blockade are because of differences in the relative contributions of the sympathetic and parasympathetic nervous system in control of blood pressure with age. Muscle sympathetic nerve activity (microneurography, peroneal nerve), heart rate (HR), and blood pressure were recorded before and during incremental doses of TMP camsylate until ganglionic blockade was achieved (absence of muscle sympathetic nerve activity and <5-bpm increase in HR during a valsalva maneuver; final TMP dose, 1-7 mg/min). HR variability was analyzed from the ECG waveform (WinCPRS). The dose of TMP required to achieve ganglionic blockade is positively related to basal HR variability, where women with high HR variability require a higher dose of TMP to achieve ganglionic blockade. In contrast, baseline muscle sympathetic nerve activity is inversely related with the dose of TMP required to achieve ganglionic blockade, such that women with high basal muscle sympathetic nerve activity required a lower dose of TMP. As such, the change in HR with ganglionic blockade was positively related, and the change in mean arterial pressure was inversely related, with the dose of TMP required to achieve ganglionic blockade. These data suggest loss of parasympathetic tone and increased sympathetic tone with aging contribute to the increase in blood pressure with age in women and dictate the dose of TMP that is necessary to achieve ganglionic blockade.

Heart rate variability as a biomarker of anxious depression response to antidepressant medication.

There is a need to identify biomarkers of treatment outcomes for major depressive disorder (MDD) that can be disseminated. We investigated the predictive utility of pretreatment heart rate variability (HRV) for outcomes of antidepressant medication in MDD, with pretreatment anxious depression as a hypothesized moderator of HRV effects. A large, randomized, multicenter practical trial (International Study to Predict Optimized Treatment in Depression) in patients with current nonpsychotic MDD (N=1,008; 722 completers) had three arms: escitalopram, sertraline, and venlafaxine-extended release. At pretreatment, patients were defined as having anxious (N=309) versus nonanxious (N=413) depression and their resting high-frequency HRV (root mean square of successive differences) was assessed. Patients' usual treating clinicians managed medication. At 8weeks, primary outcomes were clinician-rated depressive symptom response and remission; secondary outcomes were self-reported response and remission. Pretreatment HRV predicted antidepressant outcomes as a function of anxious versus nonanxious depression. In anxious depression, patients with higher HRV had better outcomes, whereas patients with lower HRV had poorer outcomes. In nonanxious depression, patients with lower HRV had better outcomes, whereas patients with higher HRV had poorer outcomes. Some simple effects were not significant. Results did not differ by treatment arm and remained significant when controlling for important covariates. These findings inform a precision medicine approach in which clinical and biological assessments may be integrated to facilitate treatment outcome prediction. Knowing about HRV may help determine which patients with anxious depression could benefit from antidepressants and which patients may require a different treatment approach.

Effects of Cold Stimulation on Cardiac-Vagal Activation in Healthy Participants: Randomized Controlled Trial.

BackgroundThe experience of psychological stress has not yet been adequately tackled with digital technology by catering to healthy individuals who wish to reduce their acute stress levels. For the design of digitally mediated solutions, physiological mechanisms need to be investigated that have the potential to induce relaxation with the help of technology. Research has shown that physiological mechanisms embodied in the face and neck regions are effective for diminishing stress-related symptoms. Our study expands on these areas with the design for a wearable in mind. As this study charts new territory in research, it also is a first evaluation of the viability for a wearables concept to reduce stress.ObjectiveThe objectives of this study were to assess whether (1) heart rate variability would increase and (2) heart rate would decrease during cold stimulation using a thermode device compared with a (nonstimulated) control condition. We expected effects in particular in the neck and cheek regions and less in the forearm area.MethodsThe study was a fully randomized, within-participant design. Volunteer participants were seated in a laboratory chair and tested with cold stimulation on the right side of the body. A thermode was placed on the neck, cheek, and forearm. We recorded and subsequently analyzed participants’ electrocardiogram. The cold stimulation was applied in 16-second intervals over 4 trials per testing location. The control condition proceeded exactly like the cold condition, except we manipulated the temperature variable to remain at the baseline temperature. We measured heart rate as interbeat intervals in milliseconds and analyzed root mean square of successive differences to index heart rate variability. We analyzed data using a repeated-measures ANOVA (analysis of variance) approach with 2 repeated-measures factors: body location (neck, cheek, forearm) and condition (cold, control).ResultsData analysis of 61 participants (after exclusion of outliers) showed a main effect and an interaction effect for body location and for condition, for both heart rate and heart rate variability. The results demonstrate a pattern of cardiovascular reactivity to cold stimulation, suggesting an increase in cardiac-vagal activation. The effect was significant for cold stimulation in the lateral neck area.ConclusionsThe results confirmed our main hypothesis that cold stimulation at the lateral neck region would result in higher heart rate variability and lower heart rate than in the control condition. This sets the stage for further investigations of stress reduction potential in the neck region by developing a wearable prototype that can be used for cold application. Future studies should include a stress condition, test for a range of temperatures and durations, and collect self-report data on perceived stress levels to advance findings.

Individual Differences in Attentional Capture by Pictures of Fear and Disgust as Indexed by Cardiac Responses

Abstract. Emotional stimuli automatically capture attention in ways that are relevant to the survival value of the stimuli. We have previously shown that individual differences in resting heart rate variability (HRV) were related to attentional capture by negative (fearful) and neutral distractors. However, different negative emotions such as fear and disgust may differentially capture attention. In the present study we investigated the effect of automatic attention capture by disgust and fear stimuli on behavioral and phasic heart rate responses as well as its relationship with resting heart rate variability (HRV). Twenty-eight participants (14 men) were divided into two groups based on their resting HRV. Phasic cardiac responses as well as reaction times and errors on a digit categorization task were assessed with disgust, fear, and neutral pictures as distractors. In the high HRV group disgusting distractors produced the strongest interference on the ongoing cognitive task indicated by more errors and longer reaction times as well as a deeper cardiac deceleration compared to fearful or neutral distractors. In contrast, the low HRV group showed faster reaction times to fear evoking pictures, whereas their heart rate responses and number of errors did not distinguish between the three emotional categories. Our results suggest that high HRV participants showed the emotional context appropriate responses while low HRV participants seem to be hypervigilant to fear.

A5596 Hypertensive patients have 24 hours higher heart rate variability

A5596 Hypertensive patients have 24 hours higher heart rate variability

Shift Work and Heart Rate Variability Coherence: Pilot Study Among Nurses

This study used ambient heart rate monitoring among health care workers to determine whether a novel measure of heart rate variability (HRV), as well as sleep disturbances, fatigue, or cognitive performance differed among non-rotating night shift nurses relative to those working permanent day shifts. Continuous ambulatory HRV monitoring was performed among night nurses (n = 11), and a comparison group of permanent day nurses (n = 7), over a 36-h period coinciding with the last two 12-h shifts of each participant’s work week. Symptoms and psychomotor vigilance were assessed at the end of the ambient HRV monitoring period, and no differences between shifts were observed. Day nurses exhibited an increase in hourly mean HRV coherence ratios during their sleep period, suggesting a circadian pattern of cardiorespiratory phase coupling, whereas night nurses had no increase in HRV coherence ratios during their sleep period. The HRV coherence patterns were similar to high frequency HRV power among nurses on the same shift. To the authors knowledge, this study was the first to quantify patterns of the HRV coherence ratio among shiftworkers in a non-experimental (work/home) setting. The results suggest a pattern of autonomic dysregulation among night workers during their sleep period relative to those working day shifts. The HRV coherence ratio may serve as a novel indicator of HRV dysregulation among shift workers.

Effects of Psychophysiological Reactivity to a School-Related Stressor and Temperament on Early Adolescents’ Academic Performance

This study investigated early adolescents’ psychophysiological response to a school-related stressor (SRS) as indexed by heart rate variability and examined the unique and interactive effects of heart rate variability and temperament on academic achievement. A total of 91 seventh graders watched an SRS video-clip while their heart rate variability was registered. Temperament and grades were also assessed. Heart rate variability decreased from baseline while watching the video-clip, indicating the activation of a stress response, and returned to basal level when recovering. Regression analyses revealed that among youth with an inhibited temperament, higher heart rate variability in the poststressor phase was related to better performance, whereas socially outgoing students performed well regardless of their recovery rate. These are among the first data to report on the link between early adolescents’ parasympathetic self-regulatory activity in response to an SRS, temperamental profiles, and academic functioning. Implications for theory and educational practice are discussed.