The 24-h movement behaviours composition is associated with parasympathetic modulation in preschoolers.

AIM: To investigate the associations between 24-h movement behaviours and heart rate variability (HRV) in preschool children. METHODS: A total of 123 preschoolers (4.52 ± 0.25 years old; 62 girls) were assessed for physical activity (PA) and sedentary behaviour (SB) using an accelerometer (Actigraph WGT3x). Sleep duration (SD) was parent-reported. Children were laid down in a supine position for 10 min to assess HRV data. The R-R intervals recorded during the last 5 min of this period were analysed. We conducted compositional analysis in R studio, and the significance level was 95%. All ethical procedures were followed, and the study had the approval of the local ethical board. RESULTS: When considered as a composition, adjusted for age, body mass index and sex, the 24-h movement composition (PA, SB and SD) significantly predicted better parasympathetic modulation (Root mean square of the successive differences [RMSSD] [p = 0.04; r2 = 0.13]), but not high frequency (HF) (nu) (p = 0.51, r2 = 0.01), low frequency (nu) (p = 0.52, r2 = 0.02),or standard deviation (standard deviation of normal-to-normal intervals) (p = 0.55, r2 = 0.02), respectively. CONCLUSION: These results suggest the 24-h movement composition predicted the RMSSD time-domain index related to parasympathetic activity.

Parasympathetic neurons derived from human pluripotent stem cells model human diseases and development.

Autonomic parasympathetic neurons (parasymNs) control unconscious body responses, including "rest-and-digest." ParasymN innervation is important for organ development, and parasymN dysfunction is a hallmark of autonomic neuropathy. However, parasymN function and dysfunction in humans are vastly understudied due to the lack of a model system. Human pluripotent stem cell (hPSC)-derived neurons can fill this void as a versatile platform. Here, we developed a differentiation paradigm detailing the derivation of functional human parasymNs from Schwann cell progenitors. We employ these neurons (1) to assess human autonomic nervous system (ANS) development, (2) to model neuropathy in the genetic disorder familial dysautonomia (FD), (3) to show parasymN dysfunction during SARS-CoV-2 infection, (4) to model the autoimmune disease Sjögren's syndrome (SS), and (5) to show that parasymNs innervate white adipocytes (WATs) during development and promote WAT maturation. Our model system could become instrumental for future disease modeling and drug discovery studies, as well as for human developmental studies.

Rhinorrhea and watery eyes in infancy and risk of attention-deficit hyperactivity disorder in school-age children.

Increased parasympathetic nervous system (PNS) activity is associated with attention-deficit/hyperactivity disorder (ADHD) inattentive symptoms, but not hyperactive-impulsive symptoms, and may contribute to inattentive subtype etiology. Guided by prior work linking infant rhinorrhea and watery eyes without a cold (RWWC) to PNS dysregulation, we examined associations between infant RWWC and childhood ADHD symptoms in a longitudinal cohort of Black and Latinx children living in the context of economic disadvantage (N = 301 youth: 158 females, 143 males). Infant RWWC predicted higher inattentive (relative risk [RR] 2.16, p < .001) but not hyperactive-impulsive (RR 1.53, p = .065) ADHD symptoms (DuPaul scale), administered to caregivers at child age 8-14 years. Stratified analyses revealed that these associations were present in females but not males, who were three times more likely to have higher ADHD current total symptoms if they had infant RWWC than if they did not. Additionally, associations between RWWC and inattention symptoms were observed only in females. RWWC may thus serve as a novel risk marker of ADHD inattentive-type symptoms, especially for females.

Efficacy and safety of trigeminal parasympathetic pathway stimulation for dry eye: A systematic review and meta-analysis.

This study aimed to investigate the efficacy and safety of trigeminal parasympathetic pathway (TPP) stimulation in the treatment of dry eye. A comprehensive search for randomized clinical trials was performed in seven databases (MEDLINE, Embase, CENTRAL, etc.) up to 28 February 2023. After screening the suitable studies, the data were extracted and transformed as necessary. Data synthesis and analysis were performed using Review Manager 5.4, and the risk of bias and quality of evidence were evaluated with the recommended tools. Fourteen studies enrolling 1714 patients with two methods (electrical and chemical) of TPP stimulation were included. Overall findings indicate that TPP stimulation was effective in reducing subjective symptom score (standardized mean difference [SMD], -0.45; 95% confidence interval [CI], -0.63 to -0.28), corneal fluorescence staining (mean difference [MD], -0.78; 95% CI, -1.39 to -0.18), goblet cell area (MD, -32.10; 95% CI, -54.58 to -9.62) and perimeter (MD, -5.90; 95% CI, -10.27 to -1.53), and increasing Schirmer's test score (SMD, 0.98; 95% CI, 0.65 to 1.31) and tear film break-up time (SMD, 0.57; 95% CI, 0.19 to 0.95). Compared to inactive or low-activity stimulation controls, it has a higher incidence of adverse events. Therefore, TPP stimulation may be an effective treatment for dry eye, whether electrical or chemical. Adverse events are relatively mild and tolerable. Due to the high heterogeneity and low level of evidence, the current conclusions require to be further verified.

Childhood psychological maltreatment and social anxiety in college students: The roles of parasympathetic nervous system activity and parent-child separation experience.

BACKGROUND: Childhood psychological maltreatment is a risk factor for social anxiety in adulthood. Parent-child separation, as one of the most serious adversities in early life, may exacerbate the risk of psychological maltreatment and influence the interactions between childhood psychological maltreatment and biological sensitivity to stress in relation to social anxiety. However, there has been a dearth of work on this issue. OBJECTIVE: This study investigated the interactive effects between childhood psychological maltreatment and parasympathetic nervous system (PNS) activity on social anxiety in college students by comparing those who experienced parent-child separation versus those who did not. Potential sex differences in the aforementioned associations were tested as an exploratory aim. PARTICIPANTS AND SETTING: Data were obtained from 264 college students (Mage = 18.45 years, SD = 0.69), including 156 students who experienced parent-child separation and 108 students without this experience. METHODS: Participants completed measures of childhood psychological maltreatment and social anxiety and reported their parent-child separation experience. The data of PNS activity, measured by respiratory sinus arrhythmia (RSA) reactivity, were obtained during the Trier Social Stress Test (TSST) in the lab. RESULTS: Childhood psychological maltreatment was positively associated with college students' social anxiety. RSA reactivity moderated the relationship between childhood psychological maltreatment and college students' social anxiety, and the moderating role of RSA reactivity varied with parent-child separation experience and sex. CONCLUSIONS: Parent-child separation experience influenced the biosocial interactions between childhood psychological maltreatment and PNS activity in relation to individuals' social anxiety, and this effect persisted in adulthood.

The relationship between sustained attention and parasympathetic functioning.

Sustained attention (SA) is an important cognitive ability that plays a crucial role in successful cognitive control. Resting vagally-mediated heart rate variability (vmHRV) has emerged as an informative index of parasympathetic nervous system activity and a sensitive correlate of individual differences in cognitive control. However, it is unclear how resting vmHRV is associated with individual differences in sustained attention. The primary aim of the current study was to assess if resting vmHRV was associated with individual differences in performance on a neuropsychological assessment of sustained attention. We further aimed to characterize the relationship between resting vmHRV and dispositional factors related to sustained attention, specifically attentional errors in daily life, self-regulation, mindfulness and media-multitasking. Based on previous work, we hypothesized higher resting vmHRV would be associated with better sustained attention across task-based and self-report measures. We did not find resting vmHRV to be significantly associated with performance measures on a task-based assessment of sustained attention. Further, resting vmHRV was not significantly associated with attention errors, self-regulation, mindfulness, or media-multitasking. This work stands to expand the current understanding between parasympathetic functioning, cognition, and behavior, investigating the unexplored domain of sustained attention and related dispositional factors.

Need to Take Heart? Talk to Your Psychiatrist for 20 Minutes.

ABSTRACT: A powerful correlation exists between the equilibrium of the sympathetic and parasympathetic nervous systems and heart rate variability (HRV). Thus, HRV is useful as a physiological index of both physical and emotional health; autonomic nervous system dysregulation, with a sympathetic predominance and a low HRV, has been associated with a variety of physical (cardiovascular, neurological) and psychiatric disorders. We used a validated algorithm of measuring the HRV (noninvasive, 2-minute approach) in new psychiatric outpatients in first author's private practice. The subjects had an initial measurement, followed by a 20-minute consultation with minimal supportive psychotherapy, followed by an exit measurement. The initial study spanned the "COVID months"; to control for this variable, an identical study was performed in 2023. There was a highly significant decrease in the sympathetic predominance in the test groups; no such trend was found in the control groups. A short psychiatry consultation may be sufficient to decrease patients' sympathetic hyperactivity and improve their well-being.

Autonomic nervous system responses to social stimuli among autistic individuals: A systematic review and meta-analysis.

Physiological responses to environmental and social stimuli have been studied broadly in relation to psychological states and processes. This may be especially important regarding autistic individuals, who show disparities in social interactions. However, findings from studies assessing autonomic nervous system (ANS) responses of autistic individuals present contradictions, with reports showing both autonomic disparities and intact autonomic functioning. The current study aimed to review the existing literature and to estimate if there is a difference between autistic individuals and neurotypical (NT) individuals in their autonomic responses to social stimuli. Furthermore, the study examined factors that may moderate this difference, including the type of physiological function measured, the level of participation required, as well as the age and intellectual functioning of the participants. The meta-analysis revealed a small and statistically insignificant overall difference between autistic and NT individuals, albeit with high heterogeneity. A further nested moderator analysis revealed a significant difference between autistic and NT individuals in physiological response that reflects mainly a parasympathetic nervous system (PNS) activity. Another difference was found in physiological response that reflects a combined activity of the sympathetic and parasympathetic systems, but only for experimental tasks that demanded active participation in social interactions. These results suggest a distinctiveness in autonomic regulation of autistic individuals in social situations, and point to the PNS as an important study objective for future investigation.

PEP reward reactivity moderates the effects of RSA reactivity on antisocial behavior and substance use.

Integrating Polyvagal Theory and Reinforcement Sensitivity Theory (RST), we examined pre-ejection period (PEP) reward reactivity, which was suggested to index trait impulsivity, as a moderator between respiratory sinus arrhythmia (RSA) reactivity and antisocial behavior (ASB), and substance use in an urban male, adult sample. To understand the inconsistent findings between RSA reactivity and externalizing problems, we proposed to study both negatively and positively valenced tasks for RSA reactivity and to include PEP reward reactivity as a moderator for the RSA-behavior link. Data were collected from an urban sample of 131 male adults (active offenders, demographic controls, and college students). ICG (impedance cardiography) and ECG (electrocardiogram) were recorded, computing PEP (sympathetic nervous system activity marker) and RSA (parasympathetic nervous system activity marker), while participants completed the modified Trier Social Stress Test and a simple reward task. Reactivity was calculated by subtracting the baseline from the task activity. Consistent with prior studies, more RSA withdrawal to stress and less PEP shortening to reward predicted the most ASB and substance use. Less RSA withdrawal to reward and more PEP shortening to reward predicted the most ASB and substance use. We incorporated autonomic space, RST, and Polyvagal Theory to discuss our findings, and specifically highlight how clarifying what each reactivity captures based on the task demand (e.g., presence of social threat, need for vagal-mediated social affiliative behavior) can illuminate our understanding of the result patterns.

Effects of prenatal opioid exposure on infant sympathetic and parasympathetic nervous system activity.

Prenatal opioid exposure has been associated with developmental problems, including autonomic nervous system dysregulation. However, little is known about the effects of prenatal opioid exposure on the autonomic nervous system beyond the first days of life, particularly across both the parasympathetic and sympathetic branches, and when accounting for exposure to other substances. The present study examined the effects of prenatal exposure to opioid agonist therapy (OAT, e.g., methadone) and other opioids on infant autonomic nervous system activity at rest and in response to a social stressor (the Still-Face Paradigm) at six months among 86 infants varying in prenatal opioid and other substance exposure. Results indicated that OAT and other opioids have unique effects on the developing autonomic nervous system that may further depend on subtype (i.e., methadone versus buprenorphine) and timing in gestation. Results are discussed in the context of theoretical models of the developing stress response system.

Effectiveness of spinal manipulation in influencing the autonomic nervous system - a systematic review and meta-analysis.

BACKGROUND: Spinal manipulation (SM) has been hypothesized to influence the autonomic nervous system (ANS). Further, it has been proposed that the effects may vary depending on the segment manipulated. The aim of this systematic review was to synthesize the current level of evidence for SM in influencing the ANS in healthy and/or symptomatic population. METHODS: Various databases (n = 8) were searched (inception till May 2023) and 14 trials (n = 618 participants) were included in the review. Two authors independently screened, extracted and assessed the risk of bias in included studies. The data were synthesized using standard mean differences and meta-analysis for the primary outcome measures. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of the body of evidence for each outcome of interest. RESULTS: Overall, there was low quality evidence that SM did not influence any measure of ANS including heart rate variability (HRV), oxy-hemoglobin, blood pressure, epinephrine and nor-epinephrine. However, there was low quality evidence that cervical spine manipulation may influence high frequency parameter of HRV, indicating its influence on the parasympathetic nervous system. CONCLUSION: When compared with control or sham interventions, SM did not alter the ANS. Due to invalid methodologies and the low quality of included studies, findings must be interpreted with great caution. Future studies are needed which employ rigorous data collection processes to verify the true physiological implications of SM on ANS.

Respiratory sinus arrhythmia (RSA), vagal tone and biobehavioral integration: Beyond parasympathetic function.

Linchpin to the entire area of psychophysiological research and discussion of the vagus is the respiratory and cardiovascular phenomenon known as respiratory sinus arrhythmia (RSA; often synonymous with high-frequency heart-rate variability when it is specifically linked to respiratory frequency), i.e. rhythmic fluctuations in heart rate synchronized to inspiration and expiration. This article aims 1) to clarify concepts, terms and measures commonly employed during the last half century in the scientific literature, which relate vagal function to psychological processes and general aspects of health; and 2) to expand upon an earlier theoretical model, emphasizing the importance of RSA well beyond the current focus upon parasympathetic mechanisms. A close examination of RSA and its relations to the vagus may 1) dispel certain commonly held beliefs about associations between psychological functioning, RSA and the parasympathetic nervous system (for which the vagus nerve plays a major role), and 2) offer fresh perspectives about the likely functions and adaptive significance of RSA, as well as RSA's relationship to vagal control. RSA is neither an invariably reliable index of cardiac vagal tone nor of central vagal outflow to the heart. The model here presented posits that RSA represents an evolutionarily entrenched, cardiovascular and respiratory phenomenon that significantly contributes to meeting continuously changing metabolic, energy and behavioral demands.

Age-related structural and functional changes of the intracardiac nervous system.

BACKGROUND: Although aging is known to be associated with an increased incidence of both atrial and ventricular arrhythmias, there is limited knowledge about how Schwann cells (SC) and the intracardiac nervous system (iCNS) remodel with age. Here we investigate the differences in cardiac SC, parasympathetic nerve fibers, and muscarinic acetylcholine receptor M2 (M2R) expression in young and old mice. Additionally, we examine age-related changes in cardiac responses to sympathomimetic and parasympathomimetic drugs. METHODS AND RESULTS: Lower SC density, lower SC proliferation and fewer parasympathetic nerve fibers were observed in cardiac and, as a control sciatic nerves from old (20-24 months) compared to young mice (2-3 months). In old mice, chondroitin sulfate proteoglycan 4 (CSPG4) was increased in sciatic but not cardiac nerves. Expression of M2R was lower in ventricular myocardium and ventricular conduction system from old mice compared to young mice, while no significant difference was seen in M2R expression in sino-atrial or atrio-ventricular node pacemaker tissue. Heart rate was slower and PQ intervals were longer in Langendorff-perfused hearts from old mice. Ventricular tachycardia and fibrillation were more frequently observed in response to carbachol administration in hearts from old mice versus those from young mice. CONCLUSIONS: On the background of reduced presence of SC and parasympathetic nerve fibers, and of lower M2R expression in ventricular cardiomyocytes and conduction system of aged hearts, the propensity of ventricular arrhythmogenesis upon parasympathomimetic drug application is increased. Whether this is caused by an increase in heterogeneity of iCNS structure and function remains to be elucidated.

Noncontact Evaluation Method for Autonomic Nervous System Activity during Exercise Using RGB Camera.

For efficient exercise, motor functions, heart rate, oxygen uptake (which are controlled by autonomic nervous system activity), heat acclimation-related functions, such as sweating, and thermoregulation must work properly during exercise. In this research, a noncontact method of measuring capillary contraction and dilation, one of the autonomic nervous system activities, using only a commercial web camera was developed. The absorption rate by haemoglobin in blood differs for each wavelength of light. When the capillaries in the face contract or dilate, the colour component of the light reflected from the face changes. The focus of this study was on the changes in the green and blue values of the face image. Green light reaches the dermis, where capillaries are located, while blue light reaches only the epidermis. The G/B ratio, the green value divided by the blue value, shows the changes in capillary contraction and dilation. An experiment was conducted to validate the G/B ratio method. Ten subjects (23 ± 1.6 years of age) participated in the experiment, and face movement and heart rate were measured during an aerobic bike exercise test. The results showed that, when the heart rate increased, the G/B ratio decreased immediately after the start of exercise. After the exercise stopped, the heart rate decreased immediately, and the G/B ratio increased. The G/B ratio revealed that the sympathetic nervous system became dominant during exercise, causing facial capillaries to dilate, and that the parasympathetic nervous system became dominant after exercise, causing facial capillaries to constrict.

Exploring the aperiodic nature of parasympathetic activity during sleep in idiopathic gastroparesis.

The parasympathetic nervous system is necessary to regulate both sleep and digestion. Investigating abnormalities during the controlled setting of sleep can shed light on digestion, specifically for patients with idiopathic gastroparesis. In this study, we specifically investigate heartbeat-derived parasympathetic activity during sleep at very low frequencies, relevant to sleep cycle regulation. To do this, we adapt a method that extracts both periodic and aperiodic information from the power spectral density and recognize that the aperiodic activity may contain information relevant to very low frequencies. After testing on both synthetic noise data (pink and white) and overnight data from seven healthy controls and idiopathic gastroparetics, we find that the healthy controls' low-frequency aperiodic activity reflects pink noise structure, while the majority of the patients' aperiodic activity reflects white noise structure. At these low frequencies, these differences suggest differences in autonomic sleep cycle regulation.Clinical Relevance- This methodology can be optimized to track the health of the parasympathetic nervous system and suggest whether individual disease etiology is autonomic-related.

Resting parasympathetic activity is associated with malodor-induced change in perceived foreignness of speakers.

INTRODUCTION: To protect against infection, individuals have evolved context-dependent pathogen-avoidant strategies, including selective social behaviors aimed at avoiding foreign individuals who may possess greater risk of infection. Parasympathetic nervous system (PNS) activity is associated with social engagement and regulation of the classical immune system but has not been widely investigated in relation to changes in intergroup perception and the behavioral immune system. METHOD: The current research investigated the relationship between parasympathetic activity and perceived foreignness of in and outgroup speakers during exposure to a pathogen-relevant odor (butyric acid). High-frequency heart rate variability was measured at rest and while participants rated foreignness of speakers with and without the odor present. RESULTS: Findings show that exposure to the odor was associated with higher foreignness perceptions of outgroup speakers and lower foreignness perceptions of ingroup speakers. This effect was especially evident among individuals with higher resting parasympathetic activity. CONCLUSION: These results suggest that the PNS may play a role in changes in social perceptions during a behavioral immune response.

A multiscale predictive digital twin for neurocardiac modulation.

Cardiac function is tightly regulated by the autonomic nervous system (ANS). Activation of the sympathetic nervous system increases cardiac output by increasing heart rate and stroke volume, while parasympathetic nerve stimulation instantly slows heart rate. Importantly, imbalance in autonomic control of the heart has been implicated in the development of arrhythmias and heart failure. Understanding of the mechanisms and effects of autonomic stimulation is a major challenge because synapses in different regions of the heart result in multiple changes to heart function. For example, nerve synapses on the sinoatrial node (SAN) impact pacemaking, while synapses on contractile cells alter contraction and arrhythmia vulnerability. Here, we present a multiscale neurocardiac modelling and simulator tool that predicts the effect of efferent stimulation of the sympathetic and parasympathetic branches of the ANS on the cardiac SAN and ventricular myocardium. The model includes a layered representation of the ANS and reproduces firing properties measured experimentally. Model parameters are derived from experiments and atomistic simulations. The model is a first prototype of a digital twin that is applied to make predictions across all system scales, from subcellular signalling to pacemaker frequency to tissue level responses. We predict conditions under which autonomic imbalance induces proarrhythmia and can be modified to prevent or inhibit arrhythmia. In summary, the multiscale model constitutes a predictive digital twin framework to test and guide high-throughput prediction of novel neuromodulatory therapy. KEY POINTS: A multi-layered model representation of the autonomic nervous system that includes sympathetic and parasympathetic branches, each with sparse random intralayer connectivity, synaptic dynamics and conductance based integrate-and-fire neurons generates firing patterns in close agreement with experiment. A key feature of the neurocardiac computational model is the connection between the autonomic nervous system and both pacemaker and contractile cells, where modification to pacemaker frequency drives initiation of electrical signals in the contractile cells. We utilized atomic-scale molecular dynamics simulations to predict the association and dissociation rates of noradrenaline with the ß-adrenergic receptor. Multiscale predictions demonstrate how autonomic imbalance may increase proclivity to arrhythmias or be used to terminate arrhythmias. The model serves as a first step towards a digital twin for predicting neuromodulation to prevent or reduce disease.

Heart rate variability (HRV) as a way to understand associations between the autonomic nervous system (ANS) and affective states: A critical review of the literature.

Evidence suggests affective disorders such as depression and bipolar disorder are characterised by dysregulated autonomic nervous system (ANS) activity. These findings suggest ANS dysregulation may be involved in the pathogenesis of affective disorders. Different affective states are characterised by different ANS activity patterns (i.e., an increase or decrease in sympathetic or parasympathetic activity). To understand how ANS abnormalities are involved in the development of affective disorders, it is important to understand how affective states correlate with ANS activity before their onset. Using heart rate variability (HRV) as a tool to measure ANS activity, this review aimed to look at associations between affective states and HRV in non-clinical populations (i.e., in those without medical and psychiatric disorders). Searches on PubMed and Google Scholar were completed using the following search terms: heart rate variability, autonomic nervous system, sympathetic nervous system, parasympathetic nervous system, affective state, mood and emotion in all possible combinations. All but one of the studies examined (N = 13), demonstrated significant associations between affect and HRV. Findings suggest negative affect, encompassing both diffused longer-term experiences (i.e., mood) as well as more focused short-term experiences (i.e., emotions), may be associated with a reduction in parasympathetic activity as measured through HRV parameters known to quantify parasympathetic activity (e.g., high frequency (HF)-HRV). HRV measures typically linked to reduction in parasympathetic activity appear to be linked to negative affective states in non-clinical populations. However, given the complex and possibly non-linear relationship between HRV and parasympathetic activity, further studies need to clarify specificity of these findings. Future studies should investigate the potential utility of HRV measures as biomarkers for monitoring changes in affective states and for early detection of onset and relapse of depression in patients with affective disorders.

Associations between cortical thickness and parasympathetic nervous system functioning during middle childhood.

Positive associations have been found between cortical thickness and measures of parasympathetic cardiac control (e.g., respiratory sinus arrhythmia, RSA) in adults, which may indicate mechanistic integration between neural and physiological indicators of stress regulation. However, it is unknown when in development this brain-body association arises and whether the direction of association and neuroanatomical localization vary across development. To investigate this, we collected structural magnetic resonance imaging and resting-state respiratory sinus arrhythmia data from children in middle childhood (N = 62, Mage = 10.09, range: 8.28-12.14 years). Whole-brain and exploratory ROI analyses revealed positive associations between RSA and cortical thickness in four frontal and parietal clusters in the left hemisphere and one cluster in the right. Exploratory ROI analyses revealed a similar positive association between cortical thickness and RSA, with two regions surviving multiple comparison correction, including the inferior frontal orbital gyrus and the Sylvian fissure. Prior work has identified these cortical areas as part of the central autonomic network that supports integrative regulation of stress response (e.g., autonomic, endocrine, and behavioral) and emotional expression. Our results suggest that the association between cortical thickness and resting RSA is present in middle childhood and is similar to the associations seen during adulthood. Future studies should investigate associations between RSA and cortical thickness among young children and adolescents.

The Effect of Short-term Inhalation of Fir Essential Oil on Autonomic Nervous Activity in Middle-aged Women.

This study aimed to investigate the effect of short-term inhalation of fir essential oil on autonomic nervous activity in middle-aged women. Twenty-six women (mean age, 51.0 ± 2.9 years) participated in this study. The participants sat on a chair, closed their eyes, and inhaled fir essential oil and room air (control) for 3 min. A crossover trial was performed to eliminate the effect of the order of olfactory stimulation. Approximately half of the participants were administered stimuli in the following order: exposure to fir essential oil, then control. The remaining participants were administered control, followed by fir essential oil. Heart rate variability, heart rate, blood pressure, and pulse rate were used as indicators of the autonomic nervous system activity. The Semantic Differential method and Profile of Mood States were used as psychological indicators. The High Frequency (HF) value, an indicator of parasympathetic nerve activity reflecting a relaxed state, was significantly higher during stimulation with fir essential oil than during the control condition. The Low Frequency (LF)/(LF+HF) value, an indicator of sympathetic nerve activity reflecting awake state, was marginally lower during stimulation with fir essential oil than during the control condition. No significant differences were found in heart rate, blood pressure, and pulse rate. After inhaling fir essential oil, "comfortable," "relaxed," and "natural" feelings improved, negative moods decreased, and positive moods increased. In conclusion, inhalation of fir essential oil can help menopausal women in their physiological and psychological relaxation.