Parasympathetic Activity Research Articles

Cardiac autonomic dysfunction in Takotsubo cardiomyopathy: an observational study

Abstract Takotsubo syndrome (TTS), commonly perceived as a benign and reversible condition has received attention due to emerging registry data revealing its prognosis to be comparable to acute coronary syndrome (ACS). Following ACS, a notable subset of patients develops autonomic dysfunction, whith unfavourable prognostic implications. Periodic repolarization dynamics (PRD) and deceleration capacity (DC), derived from ECG signals, are parameters capable of quantifying cardiac autonomic function. In this study, we aimed to assess autonomic dysfunction in patients with TTC in comparison to ST-elevation myocardial infarction (STEMI) patients. Consecutive patients diagnosed with TTS were prospectively recruited into an observational, single-centre cohort study. All patients underwent a 30-minute high-resolution ecg recording. Subsequent recordings were conducted at 4 and 12 months post-acute event. PRD and DC as markers for sympathetic and parasympathetic activity, respectively, were assessed using established methods. The control group comprised patients with STEMI. Statistical comparisons between groups were performed using the Mann-Whitney U-test, with a corrected significance level for multiple testing of α< .017. Between July 2021 and December 2023, 57 patients diagnosed with TTS were recruited (interquartile range [IQR]) 69.0 years (62.0-78.0), 98.3% women. A control group was derived from a pre-existing cohort of STEMI patients, matched through propensity score matching to adjust for age and sex (median age [IQR]: 69.0 [59.0-76.0] years, 98.3% women). At baseline, there was no significant difference in PRD between TTS patients and controls (median [IQR]: TTS: 5.28deg² [3.43-9.93], STEMI: 4.40deg² [2.24-7.21]; p = .04). However, at 4 months post-acute event, PRD was notably higher in TTS patients compared to controls (median [IQR]: TTS: 5.20deg² [2.71-8.17], STEMI: 2.63deg² [1.86-4.92]; p = .011). Interestingly, at 12-month follow-up, PRD in TTS patients did not differ from that of controls (median [IQR]: TTS: 4.55deg² [2.89-8.40], STEMI: 4.15deg² [2.42-6.85]; p = .68). Regarding DC, no significant differences were observed between TTS and STEMI patients at any time point (baseline: median [IQR]: TTS: 3.95 ms [2.27-5.51], STEMI: 3.52 ms [2.30-7.24], p = .51; 4 months: median [IQR]: TTS: 6.63 ms [4.59-8.64], STEMI: 7.41 ms [4.63-9.25], p = .39; 12 months: median [IQR]: TTS: 4.98 ms [4.19-6.67], STEMI: 7.48 ms [4.92-10.28], p = .17). Patients with TTS show substantial signs of cardiac autonomic dysfunction, similar or even higher than acute STEMI patients. This dysfunction persists even up to 4 months after the acute event, whereas STEMI patients show recovery of autonomic function in this 4 month period. DC remained consistent between TTS and STEMI patients across all time points. Further research elucidating the long-term implications of these autonomic alterations is warranted to refine risk stratification and therapeutic strategies in TTS management.

No improvement in atrial arrhythmia rates in patients on baroreflex activation therapy

Abstract Background Atrial arrhythmias encompass a wide range of abnormal cardiac rhythms including atrial fibrillation, atrial flutter, and atrial tachycardia. Patients with heart failure with reduced ejection fraction (HFrEF) have increased risk of atrial arrhythmias, ultimately leading to increased morbidity. Baroreflex Activation Therapy (BAT) employs an implantable device to increase parasympathetic nervous system activity by stimulating the carotid baroreceptors thereby reducing afterload and heart failure symptoms. In our prior study, BAT therapy has been shown to reduce hospitalization rates in patients with HFrEF. However, the effects of BAT on atrial arrhythmia has never been studied. Objective In this study, we analyzed the effects of BAT on atrial arrhythmia rates in patients with HFrEF. Methods Patients with HFrEF with BAT therapy for at least 12-months at a hospital were retrospectively studied. Inclusion criteria includes implantable cardioverter-defibrillator (ICD) placement of at least 12-months pre- and post-BAT therapy. Additionally, patients diagnosed with atrial arrhythmias prior to the study timeline were excluded. Atrial arrhythmia rates 6 and 12-months pre-BAT therapy and 6 and 12-months post-BAT therapy were compared. Atrial arrhythmia episodes were recorded through ICD interrogation every 1-3 months in the clinic. Of the 31 identified patients on BAT therapy, 11 patients fit the inclusion criteria. For the 11 patients in the study, 3 identified as female and 8 identified as male, 6 identified as white, 4 identified as Hispanic, and 1 identified as African-American with a mean age of 59.8 ± 17.4 years. The average left ventricular ejection fraction pre-BAT therapy was 23.8 ± 10.8%. Results The mean average atrial arrhythmia rates for 6-month pre-BAT therapy and 6-month post-BAT therapy were 0.12/month ± 0.40 and 1.32/month ± 2.76 respectively (p=0.18), suggesting no differences in atrial arrhythmia rates at 6-months with BAT therapy. The mean average atrial arrhythmia rates for 12-month pre-BAT therapy and 12-month post-BAT therapy were 0.11/month ± 0.35 and 2.40/month ± 5.84 respectively (p=0.22), suggesting no differences in atrial arrhythmia rates at 12-months with BAT therapy. Conclusion Although BAT therapy has been shown to decrease hospitalization rates, BAT therapy is not associated with decreased atrial arrhythmia rates at 6 months and 12 months.

Can HRV Biofeedback Training Improve the Mental Resilience of Icelandic Police Officers?

High heart rate variability (HRV) is increasingly recognized as an indicator of a healthy regulatory system, reflecting the dynamic balance between sympathetic (SNS) and parasympathetic (PSNS) nervous system activity. According to the neurovisceral integration model, this balance is managed by the central autonomic network (CAN), comprised of specific brain regions involved in emotional, attentional, and autonomic regulation. HRV thus reflects the performance of the cognitive, affective, and autonomic regulation system. Numerous studies support the relationship between HRV and the CAN, including research on HRV biofeedback training (HRVBF). Studies on the effectiveness of HRVBF for professions such as police officers have shown improvements in self-regulation, decision-making, and performance. However, few studies have specifically explored HRVBF's influence on HRV metrics in police officers, highlighting a need for further research. This study addresses this gap by randomly assigning 27 Icelandic police officers to intervention or wait-list control groups. The intervention group underwent a five-week HRVBF program, including group and individual training sessions. Results showed significant increases in HRV metrics for the intervention group, indicating improved autonomic function and stress resilience. Mental resilience increased significantly as measured by subjective measures of attentional control, mindful awareness, and reduced fatigue. These findings support the efficacy of HRVBF in enhancing HRV and mental resilience for police officers, suggesting its applicability and potential for integration into existing training programs.

Autonomic Modulation in Parkinson’s Disease Using Whole-Body Cryostimulation: A Pilot Study

Background: Parkinson’s disease (PD) is a multifaceted neurodegenerative disorder that progressively affects both the central and peripheral nervous systems. This pilot study aimed to examine the effects of repeated whole-body cryostimulation (WBC) sessions on the sympathovagal balance in PD patients and correlate heart rate variability (HRV) indexes with peripheral biomarkers of the autonomic nervous system (ANS). Methods: Seventeen PD patients with mild to moderate motor severity underwent a 10-session WBC cycle over 5 consecutive days. Thirteen patients (6 males, 7 females; mean age 64.5 ± 9.01 years; mean disease duration 5.4 ± 2.3 years) completed the protocol. Cardiac autonomic activity was assessed through HRV measures including RR interval variability (RR mean, RR min, RR max), power density of high and low frequencies (HF, LF), RMSSD, and the LF/HF ratio. Systemic sympathetic activity was evaluated via circulating blood catecholamine levels. Results: Significant increases were observed in RR mean, RR min, RR max, RMSSD, and HF spectrum, indicating enhanced parasympathetic activity. Blood pressure remained stable, suggesting safety. Conclusions: These findings provide initial support to WBC as a potential “rehabilitation booster” in PD, enhancing sympathovagal balance. Further research is needed to explore the long-term benefits of WBC in PD management.

The Effects of a Single Vagus Nerve’s Neurodynamics on Heart Rate Variability in Chronic Stress: A Randomized Controlled Trial

Background: The modulation of the autonomic nervous system’s activity, particularly increasing its parasympathetic tone, is of significant interest in clinical physiotherapy due to its potential benefits for stress-related conditions and recovery processes. This study evaluated the effectiveness of the addition of neurodynamics in enhancing parasympathetic activation in subjects with chronic stress. Methods: A clinical trial randomly assigned participants to a group with neurodynamics (6 bpm breathing protocol + manual therapy + neurodynamic technique) or a group without neurodynamics (6 bpm breathing protocol + manual therapy only). Metrics of heart rate variability (HRV), including the Mean Heart Rate (Mean HR), standard deviation of intervals between consecutive heartbeats (SDNN), Heart Rate Difference (Diff. HR), Root Mean Square of Successive Differences (RMSSD), number of intervals differing by more than 50 ms (NN50), percentage of consecutive NN intervals that differed by more than 50 ms (pNN50), and the high-frequency component measured in standardized units (HF), were assessed before, during, and after the intervention. Results: During the intervention, the group with neurodynamics showed significant changes in all variables except in the pNN50 and HF while the group without neurodynamics only showed improvements in the Mean HR, SDNN, and RMSSD. In the post-intervention phase, the group with neurodynamics maintained an increase in HRV while the group without neurodynamics experienced a decrease, suggesting an increase in sympathetic activity. Conclusions: Vagal nerve neurodynamics appear to represent an effective method for enhancing parasympathetic activation in patients with chronic stress. The results highlight the importance of a more comprehensive analysis of HRV variables in order to obtain a correct picture of the impact of interventions on the complex and multifaceted functioning of the autonomic nervous system.

Prior exposure to racial discrimination and patterns of acute parasympathetic nervous system responses to a race-related stress task among Black adults.

Black adults' prior exposure to racial discrimination may be associated with their acute parasympathetic reactivity to and recovery from a new race-related stressor. Existing analytical approaches to investigating this link obscure nuances in the timing, magnitude, and patterns of these acute parasympathetic nervous system (PNS) responses. In a re-analysis of a prior study, we utilize an hidden Markov model (HMM) approach to examine how prior experiences of racial discrimination are associated with intraindividual patterns of (1) physiological states of PNS activity and (2) patterns of and variability in transitions between these physiological states. Participants (N = 118) were Black young adults (range 18-29 years; Mage = 19.67, SDage = 2.04) who completed an online survey to index prior racial discrimination exposure, followed by an in-person lab visit during which their PNS activity in response to a race-related stress task was measured via electrocardiogram and converted into respiratory sinus arrhythmia. HMMs indicated evidence for two states: baseline and a second state representing a significant reduction in respiratory sinus arrhythmia. Most participants (93.22%) demonstrated a blunted response to the task, indicating that they did not transition from baseline during the procedure. Prior racial discrimination was not associated with HMM states or state transition parameters. Blunted physiological responses may be an important area of future investigation that could inform early life course mental and physical health screenings.

Effects of a 30-min rest with a nap chair on task performance, sleepiness, and neurophysiological measures in men with suspected brain fatigue: a randomized controlled crossover trial

BackgroundIt has been suggested that a short nap in the afternoon may improve sleepiness, alertness, and task performance. The present study evaluated the effects of a 30-min rest with a new nap chair on task performance, sleepiness, and neurophysiological measures.MethodsA randomized controlled crossover trial with a 1-week interval was carried out at the BOOCS Clinic Fukuoka in Japan. The subjects were male workers aged 20 to 64 years with suspected brain fatigue, which was defined by the Profile of Mood Status 2. The intervention was a 30-min rest with an office chair or a nap chair. The primary outcome was the performance in the Uchida-Kraepelin test. The secondary outcomes included the Karolinska Sleepiness Scale and 15-min heart rate variability (HRV). The changes after the nap-chair rest and office-chair rest were compared. Repeated measures analysis of variance with nesting was used in the statistical analysis.ResultsTwenty participants were eligible and entered the crossover trial. The overall 15-min score in the Uchida-Kraepelin test improved after the nap-chair rest and after the office-chair rest to almost the same extent (5.9 vs. 5.5 points, P = 0.68). The Karolinska Sleepiness score significantly decreased after the nap-chair rest, and the between-treatment difference in the decrease was highly significant (P = 0.0004). The average duration of sleep during rest was prominently longer in the nap-chair rest than in the office-chair rest (19.0 vs. 7.6 min, P = 0.002). No participants experienced REM sleep during the rest. LF and HF powers of the HRV were greater during the nap-chair rest than during the office-chair rest, the difference in the HF power being substantial.ConclusionA 30-min rest with the nap chair did not appreciably improve the performance in the Uchida-Kraepelin test as compared with the office-chair rest. The nap-chair rest induced a substantially longer sleep accompanied with a parasympathetic activation, thereby resulting in a material improvement in sleepiness after the rest.

Magnetic Garments Promote Parasympathetic Dominance and Improve Sleep Quality in Male Long-Distance Runners Following a 30 km Run

This study aimed to investigate the effects of high-intensity running on the autonomic nervous system and sleep quality of male long-distance runners and to examine the impact of wearing magnetic garments on these parameters. Fifteen highly trained male collegiate long-distance runners participated in a randomized, double-blind crossover study. Participants completed two 30 km runs (30k-RUN) during a 10-day training camp. After each run, they wore either magnetic (MAG) or non-magnetic control (CTRL) garments. Sleep quality and heart rate variability (HRV) were assessed using a wrist-worn device before and after each 30k-RUN. Wearing MAG garments post-30k-RUN resulted in significantly longer deep sleep duration compared to CTRL. HRV analysis revealed that the MAG condition led to a significantly higher root mean square of successive RR interval differences and high-frequency power, indicating enhanced parasympathetic activity. The low-frequency to high-frequency ratio was significantly lower in MAG than in CTRL. Perceived recovery scores were significantly higher in MAG than in CTRL. The findings of this study suggest that wearing magnetic garments following high-intensity endurance running may promote parasympathetic dominance and improve sleep quality in male long-distance runners. These findings indicate that magnetic garments may be a practical method for enhancing recovery in athletes following intense training.

Efficacy of Yoga in Reducing Depressive Symptoms: A Systematic Review

Introduction: The fast pace of changes in contemporary life increases the need to adapt, which leads to depressive pathologies due to psychological suffering. Yoga has therefore emerged as a complementary approach to the treatment of depression. Objective: To analyze the efficacy of yoga in reducing depressive symptoms. Materials and methods: This is a systematic literature review, which followed the Joanna Briggs Institute methodology for systematic reviews of efficacy, with the review protocol registered on Prospero under the code CRD42023448158. To devise the research question, the Pico strategy was adopted, in which “P” stands for people with depression, “I” for yoga; “C” for people who have not been submitted to yoga, and “O” for improvement/reduction of depressive symptoms. The requirements of the Prisma flowchart were followed and the search was conducted in the Medline/PubMed, Web of Science, Lilacs, BDEnf, Ibecs, PsycINFO, and Cinahl databases. The Jadad scale was used to assess methodological quality and the Cochrane Risk of Bias 2 to assess the risk of bias. Results: A total of 1138 studies were found, of which 10 were selected for data extraction, detailed reading, and qualitative synthesis. Yoga, especially mindfulness yoga, has been shown to be an effective intervention for various conditions, including depression. Its benefits include significant improvements in depression severity, health-related quality of life, motor dysfunction, mobility, spiritual well-being, and parasympathetic nervous system activity. Conclusion: The studies highlight the efficacy of yoga in reducing depressive symptoms in various populations and contexts, highlighting its effectiveness as a complementary therapeutic approach in the management of depression.

Adaptive responses of heart rate regulation during functional tests with breath holding

BACKGROUND: Synchronization of biorhythms in living organisms is of particular interest to researchers from the standpoint of adaptation theory. AIM: To study the characteristics of the response of regulatory influences on heart rhythm during tests with voluntary breath holding during inhalation and exhalation. MATERIAL AND METHODS: The study sample included 21 randomly selected students (9 males, 12 females) aged 20.64±1.14 years with body weight 67.19±12.98 kg, height 172.29±7.63 cm. All subjects were divided into three groups (I, II, III) according to the classification by N.I. Shlyk (2009), which is based on the predominance of central or autonomic circuits of heart rhythm regulation. A fivefold sequential ECG recording was conducted using the hardware-software complex “Varicard 3.0” with the subject seated after a five-minute rest: 1 — baseline state; 2 — voluntary breath holding during inhalation; 3 — resting state; 4 — voluntary breath holding during exhalation; 5 — resting state. Using the “Varicard 3.0” system, a mathematical analysis of heart rhythm was performed, taking into account statistical parameters of heart rhythm and indices of spectral frequency analysis. RESULTS: During the period of breath holding, heart rate variability decreased, while at rest it increased in all groups. In group I, after a breath-hold test during the rest period, eutonia was observed according to spectral analysis (HF=LF). Statistical analysis in this group demonstrated an increase in the contribution of the parasympathetic component to heart rate variability (RMSSD, pNN50, SDNN, CV), signifying the prerequisites for increased heart rate variability. In group II, after breath-holding tests, a slight decrease in sympathetic activity was observed. A tense pattern of autonomic regulation was observed during the exhalation breath-hold test, which may indicate a reduced functional state of the regulatory systems. Group III was characterized by a sharp increase in sympathetic activation in the test with breath holding during inhalation, followed by a soft correction during breath holding during exhalation, which can be regarded as an adequate response of the body to the load. At rest, after the test, the regulation pattern returned to the original one with a moderate predominance of parasympathetic activity and, accordingly, a more favorable level of heart rate variability for the body. CONCLUSION: Adaptive reactions of the heart rate variability are manifested by an increase in sympathetic activation, which, subsequently, during normal breathing, is replaced by a compensatory activation of the parasympathetic division of the autonomous nervous system. Although reactions are unidirectional, the severity can vary across the groups.

Nasal lymphatic obstruction of CSF drainage as a possible cause of Alzheimer’s disease and dementia

Alzheimer’s disease, the most common form of dementia among older adults, slowly destroys memory and thinking skills. In recent years, scientists have made tremendous progress in understanding Alzheimer’s disease, still, they do not yet fully understand what causes the disease. This article proposes a novel etiology for Alzheimer’s disease. Our hypothesis developed from a review of nuclear medicine scans, in which the authors observed a significant increase in nasal turbinate vasodilation and blood pooling in patients with hypertension, sleep apnea, diabetes and/or obesity, all risk factors for Alzheimer’s disease. The authors propose that nasal turbinate vasodilation and resultant blood pooling lead to the obstruction of normal nasal lymphatic clearance of cerebrospinal fluid and its waste products from the brain. The nasal turbinate vasodilation, due to increased parasympathetic activity, occurs alongside the well-established increased sympathetic activity of the cardiovascular system as seen in patients with hypertension. The increased parasympathetic activity is likely due to an autonomic imbalance secondary to the increase in worldwide consumption of highly processed food associated with dysregulation of the glucose regulatory system. The authors’ hypothesis offers a novel mechanism and a new paradigm for the etiology of Alzheimer’s disease and helps explain the rapid worldwide rise in the disease and other dementias which are expected to double in the next 20 years. This new paradigm provides compelling evidence for the modulation of the parasympathetic nervous system as a novel treatment strategy for Alzheimer’s disease and other degenerative brain diseases, specifically targeting nasal turbinate lymphatic flow.

Physiological monitoring of movement and manoeuvrability during a military skiing exercise

IntroductionMilitary forces receive training in various high-altitude warfare techniques to safeguard border regions and lives. Skiing is one of such practices where research evidences are limited. Therefore, a study was...

Insight of autonomic dysfunction in CLN3 disease: a study on episodes resembling paroxysmal sympathetic hyperactivity (PSH)

BackgroundRecurrent non-epileptic episodes resembling paroxysmal sympathetic hyperactivity (PSH) have been observed in adolescents with Juvenile Ceroid Lipofuscinosis (CLN3-disease) and a possible association to an autonomic dysfunction has been suggested. The objective of the present study was to investigate the dynamics of the autonomic activity up to, during, and in the time after individual attacks. We include all seven suitable CLN3 patients in Denmark ≥ 15 years of age. HRV parameters were assessed from continuous heart rate monitoring during seven consecutive days and a particular focus of HRV parameters was obtained in close temporal context to clinically recurrent PSH-like episodes. In addition, the likelihood of PSH was assessed by caregiver’s description and by video documentation.ResultsRespectively eight and five episodes were recorded in two patients (18 and 20 years of age). The episodes were all safely superior to the cut off values of the clinical assessment score to be considered PSH-like episodes. During all 13 episodes, HRV revealed a statistically significant decrease in root mean square of successive differences (RMSSD) and standard deviation of the Poincaré-Plot interval (SD1) in the minutes prior to the clinical onset of the episodes, both indicating a sudden decrease in parasympathetic activity in advance of the onset. The reduced activity remained low during the episodes, and 15–30 min following the attack cessation, the parasympathetic activity had returned to pre-attacks levels. The sympathetic HRV parameters were unchanged resulting in a sympathetic overactivity during the episodes. In a third participant (32 years of age), in whom severity of PSH-like episodes had been gradually reduced during the last years, five episodes were registered. A similar temporally related reduction of the parasympathetic activity was found, but because the sympathetic activity decreased as well, no sympathetic dominance developed, which most reasonable is the reason to the clinically reduced expression of the episodes.ConclusionThe documented transient withdrawal of parasympathetic activity leading to a paroxysmal unbalanced sympathetic hyperactivity most probably accounts for the PSH-like episodes occurring in post-adolescent CLN3 patients. The findings shed new light on both aetiology and possible preventative and therapeutic measures.

Music therapy with adult burn patients in the intensive care unit: short-term analysis of electrophysiological signals during music-assisted relaxation

Burn patients often face elevated pain, anxiety, and depression levels. Music therapy adds to integrative care in burn patients, but research including electrophysiological measures is limited. This study reports electrophysiological signals analysis during Music-Assisted Relaxation (MAR) with burn patients in the Intensive Care Unit (ICU). This study is a sub-analysis of an ongoing trial of music therapy with burn patients in the ICU. Electroencephalogram (EEG), electrocardiogram (ECG), and electromyogram (EMG) were recorded during MAR with nine burn patients. Additionally, background pain levels (VAS) and anxiety and depression levels (HADS) were assessed. EEG oscillation power showed statistically significant changes in the delta (p < 0.05), theta (p = 0.01), beta (p < 0.05), and alpha (p = 0.05) bands during music therapy. Heart rate variability tachograms high-frequencies increased (p = 0.014), and low-frequencies decreased (p = 0.046). Facial EMG mean frequency decreased (p = 0.01). VAS and HADS scores decreased − 0.76 (p = 0.4) and − 3.375 points (p = 0.37) respectively. Our results indicate parasympathetic system activity, attention shifts, reduced muscle tone, and a relaxed state of mind during MAR. This hints at potential mechanisms of music therapy but needs to be confirmed in larger studies. Electrophysiological changes during music therapy highlight its clinical relevance as a complementary treatment for ICU burn patients.Trial registration: Clinicaltrials.gov (NCT04571255). Registered September 24th, 2020. https//classic.clinicaltrials.gov/ct2/show/NCT04571255.

HEART RATE VARIABILITY IN FOOTBALL PLAYERS AND TRACK AND FIELD ATHLETES

Objective of the study: To investigate the state of the autonomic nervous system in athletes based on heart rate variability indicators. Materials and methods: The study was conducted on 142 male athletes (67 football players and 75 track and field athletes) aged 17-20 years, with an average age of 18.5±1.5 years. Depending on the type of higher nervous activity, athletes were divided into 4 groups: sanguine (41.55%), choleric (28.87%), phlegmatic (19.01%), and melancholic (10.56%). Heart rate variability (HRV) was studied using the "BioMouse" system. A t-test for independent samples (Welch's t-test) was used to analyze the significance of differences between the groups. Results of the study: It was found that the highest adaptive capabilities were observed in phlegmatic athletes, who demonstrated high SDNN and HF values, as well as a low tension index (IN). Their calm temperament allows for better adaptation to physical exertion and maintaining a balance between sympathetic and parasympathetic activity. The lowest adaptive capabilities were observed in melancholics, who showed high IN and LF values, as well as low SDNN and HF, indicating an imbalance in the autonomic nervous system and lower resilience to physical stress. Overall, beginner athletes tended to have slightly higher heart rates and lower HRV indicators (SDNN), LF, and HF compared to more experienced athletes of the 2nd-3rd ranks. This is due to the fact that first-year athletes have not yet fully adapted to physical loads, leading to more pronounced dominance of the sympathetic nervous system and less parasympathetic activity. KEYWORDS: variability, heart rate, athletes, football players, track and field athletes, autonomic nervous system, physical exertion

The Dynamics of Heart Rate Asymmetry and Situational Sleepiness from Evening to Night: The Role of Daytime Sleepiness.

The relationship between daytime sleepiness and heart rate asymmetry (HRA) during the transition from evening to night is crucial for understanding autonomic regulation and its implications for alertness. This study aims to investigate how daytime sleepiness influences HRA dynamics from evening to night and how situational sleepiness correlates with HRA metrics. HRA metrics were calculated at 8 P.M., 9 P.M., and 10 P.M. in 50 participants, categorized into 'Lower Normal' and 'Higher Normal' daytime sleepiness groups based on Epworth Sleepiness Scale (ESS) scores. Situational sleepiness was assessed using the Karolinska Sleepiness Scale (KSS) and Stanford Sleepiness Scale (SSS). The results demonstrated that individuals with 'Higher Normal' daytime sleepiness exhibited lower HRA metrics at 10 P.M. compared to those with 'Lower Normal' daytime sleepiness, supporting the suggestion that higher daytime sleepiness correlates with reduced parasympathetic activity and diminished autonomic responsiveness. Significant negative correlations between situational sleepiness and HRA metrics were observed in the 'Higher Normal' group, particularly with the SSS. Therefore, increased daytime sleepiness affects HRA dynamics by decreasing parasympathetic activity and altering autonomic regulation at the beginning of the biological night (10 P.M.). These findings suggest potential applications for enhancing drowsiness detection and managing fatigue in safety-critical environments.

Heart Rate Variability, Blood Pressure and Peripheral Oxygen Saturation during Yoga Adham and Mahat Breathing Techniques without Retention in Adult Practitioners.

Background: Heart rate variability (HRV) is the change in time intervals between heart beats, reflecting the autonomic nervous system's ability to adapt to psychological and physiological demands. Slow breathing enhances parasympathetic activity, increasing HRV. Pranayama, a yoga breathing technique, affords the conscious regulation of respiration frequency. This study aimed to characterize HRV, blood pressure and peripheral oxygen saturation of basic yoga breathing slow techniques with regular yoga practitioners. Methods: In total, 45 yoga practitioners were included in the study (including 7 males, mean age of 54.04 ± 11.97 years) with varying levels of yoga experience (minimum 3 months, maximum 37 years). Participants performed three breathing conditions: baseline (control) and two yoga techniques (abdominal (adham) and complete (mahat)) breathing, each for 10 min in the supine position (i.e., savasana). For each condition, respiratory frequency, heart rate (HR), blood pressure and peripheral oxygen levels were collected. Results: The findings revealed that both abdominal and complete yoga breathing techniques promoted a decrease in respiratory frequency (p < 0.001, r = 0.61; p < 0.001, r = 0.61, respectively), and an increase in peripheral oxygen saturation (p < 0.001, r = 0.50; p < 0.001, r = 0.46, respectively), along with blood pressure decreases in all mean values, and a significant decrease in systolic pressure, considering all conditions (p = 0.034, W = 0.08). There were significant increases in standard deviation of HR during abdominal and complete yoga breathing techniques compared with the baseline (p = 0.003, r = 0.31; p < 0.001, r = 0.47, respectively), indicating enhanced parasympathetic activity. Moreover, the complete breathing technique exhibited the greatest variability in HRV measures, with several significant differences compared with abdominal breathing (standard deviation of HR, p < 0.001, r = 0.42; SD2, standard deviation of points perpendicular to the Poincaré parallel line, p < 0.003, r = 0.31; SD1/SD2, p < 0.003, r = 0.31), suggesting a more profound impact on autonomic modulation. Conclusions: simple, inexpensive and non-intrusive abdominal and complete yoga breathing techniques can effectively and momentarily enhance HRV and oxygen saturation in adults, mature adults and the elderly.

The infant parasympathetic nervous system is socially embedded and dynamic at multiple timescales, within and between people.

Human interpersonal capacities emerge from coordinated neural, biological, and behavioral activity unfolding within and between people. However, developmental research to date has allocated comparatively little focus to the dynamic processes of how social interactions emerge across these levels of analysis. Second-person neuroscience and dynamic systems approach together to offer an integrative framework for addressing these questions. This study quantified respiratory sinus arrhythmia and social behavior (∼360 observations per system) from 44 mothers and typically developing 9-month-old infants during a novel modified "still-face" (text message perturbation) task. Stochastic autoregression models indicate that the infant parasympathetic nervous system is coupled within and between people second by second and is sensitive to social context. Intraindividual, we found positive coupling between infants' parasympathetic nervous system activity and their social behavior in the subsequent second, but only during the moments and periods of active caregiver engagement. Between people, we found a bidirectional coregulatory feedback loop: Mothers' parasympathetic activity positively predicted that of their infant in the subsequent second, a form of synchrony that decreased during the text message perturbation and did not fully recover. Conversely, infant parasympathetic activity negatively predicted that of their mother at the subsequent second, a form of synchrony that was invariant over social context. Findings reveal unidirectional parasympathetic coupling within infants and a complementary allostatic feedback loop between mother and infant parasympathetic systems. They offer novel evidence of a dynamic, socially embedded parasympathetic system at previously undocumented timescales, contributing to both basic science and potential clinical targets to better support adaptive, multisystem social development. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Measuring the Pupillary Light Reflex Using Portable Instruments in Applied Settings.

The early components of the pupillary light reflex (PLR) are governed by the parasympathetic nervous system. The use of cheap, portable pupillometry devices may allow for the testing of parasympathetic-system health in field settings. We examined the reliability of two portable instruments for measuring the PLR and their sensitivity to individual differences known to modulate the PLR. Parameters of the PLR were measured in a community sample (N = 108) in a variety of field settings. Measurements were taken using a commercial pupillometer (NeuroLight, IDMED) and an iPhone using the Reflex Pro PLR analyser (Brightlamp). The parameters of baseline pupil diameter, constriction latency, amplitude and relative amplitude of constriction, and constriction velocity were measured. Individual differences related to age, levels of anxiety, and post-traumatic stress disorder (PTSD) symptomology were assessed. Some measures could not be attained using the iPhone under these field conditions. The reliability of the measures was high, save for the measurement of contraction latency which was particularly unreliable for the iPhone system. The parameters of the PLR showed the same internal relationships as those established in laboratory-based measurements. Age was negatively correlated with all the reliable PLR parameters for both systems. Effects of anxiety and PTSD symptomology were also apparent. The study demonstrated that a hand-held portable infrared pupillometer can be used successfully to measure the PLR parameters under field settings and can be used to examine individual differences. This may allow these devices to be used in workplaces, sports fields, roadsides, etc., to examine parasympathetic activity where needed.

Impact of slouching on heart rate variability and cardiovascular health among medical students

Background: Medical students frequently adopt poor postures such as slouching potentially impacting health. Heart rate variability (HRV) serves as an indicator of autonomic nervous system function, correlated with cardiovascular health. Aims and Objectives: The objective of the study was to compare HRV parameters among medical students in three postures: Sitting erect, easy pose (cross-legged), and slouching (stooping head and shoulders). Materials and Methods: A comparative cross-sectional study enrolled 26 male medical students. Participants were instructed to maintain each posture for 5 min while HRV was recorded using a Polar V800. Time domain and frequency domain parameters among different postures were analyzed using Friedman’s test and post hoc tests for pairwise comparisons. P&lt;0.05 was considered significant. Data were expressed as median interquartile range. Results: Significant differences were observed in HRV parameters between postures. The easy pose demonstrated a significantly higher median value of root mean square of differences of successive RR intervals (48.28 ms vs. 35.35 ms) and pNN50% (24.40% vs. 13.62%) compared to slouching. Frequency domain analysis revealed a significantly higher median value of high-frequency (HF) power in easy pose (626.56 ms² vs. 378.15 ms²) and HF normalized unit (33.78 vs. 22.55) compared to slouching. A lower low frequency (LF)/HF ratio and (1.96 vs. 3.43) lower LF normalized unit (66.18 vs. 77.30) was also seen in easy pose. Although statistically not significant, the parasympathetic indicators of HRV were higher in erect sitting compared to slouching posture. Conclusion: Among medical students, adopting the easy pose (cross-legged sitting) appeared to enhance HRV and thus increase parasympathetic activity, whereas adopting slouching postures decreased it.