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This systematic review aims to evaluate which effects nature exposure has on stress in women and get a more objective viewpoint using measurements of physiological markers of stress to complement the many studies using subjective questionnaires. A search was done on Scopus, Medline EBSCO, and Web of Science for peer-reviewed, published, and original research. Five studies met the inclusion criteria and were included in this review. The outcome measurements included were activity in the autonomic nervous system (ANS) measured with heart-rate variability (HRV) and cerebral activity measured by near-infrared spectroscopy (NIRS). With the definition of Shinrin-Yoku in mind, nature exposure was walking in or watching the natural environment, compared to walking in or watching an urban environment. In this systematic review, four of five studies found significant results that nature exposure alleviated stress in women compared to an urban environment. These findings contribute to a growing body of evidence suggesting that nature is valuable in reducing stress-related illnesses in women. On the individual level, these findings show that nature exposure can be used as an evidence-based intervention to reduce stress in women. Furthermore, these findings clarify the benefits of including elements from nature in urban environments on a societal level.

Biological theory proposes that autonomic nervous system (ANS) hypo-reactivity may be more specific to proactive aggression, while ANS hyper-reactivity may be specific to affective aggression. However, the literature finds mixed support, which may be because no study to date has concurrently examined emotion dysregulation, a highly related variable, as a potential moderator. The present study examined these relationships in 76 undergraduate participants (29 men, mean age = 21.49) who identified as Caucasian (51%), African-American (23%), Asian (21%), or Other (5%). Participants completed questionnaires, a resting state task, and a provocation task. Results found that blunted overall ANS reactivity was associated with proactive aggression. Emotion dysregulation moderated the relationship between parasympathetic nervous system (PNS) and sympathetic nervous system (SNS) reactivity with both proactive (at a trending level for SNS reactivity) and affective aggression. Specifically, among those slightly above average and high on emotion dysregulation, PNS augmentation and blunted SNS reactivity were associated with proactive and affective aggression, respectively. In contrast, among those low on emotion dysregulation, PNS augmentation was associated with decreased affective aggression. Thus, among those elevated on emotion dysregulation, it may be beneficial to teach counter-regulatory strategies to reduce the impact of ANS hypo-reactivity on aggression (across function). / Psychology

<p> Hypertension is a modifiable risk factor for cardiovascular disease. The current treatment options are drug therapy and lifestyle modifications. A promising lifestyle modification therapy for the management of hypertension is isometric exercise, as several studies have demonstrated that isometric handgrip (IHG) training reduces resting arterial blood pressure (ABP) (Peters et al., 2006; Taylor et al., 2003; Wiley et al., 1992). The purpose of the present investigation was two-fold: 1) to examine the effectiveness of IHG training in reducing resting ABP in newly diagnosed hypertensive patients, in comparison to matched controls receiving advice from a physician about lifestyle modifications; and 2) to examine markers of autonomic function, specifically, heart rate variability (HRV) to determine if changes in the autonomic nervous system (ANS) existed between the two groups of hypertensive adults.</p> <p> Resting blood pressure and heart rate were assessed with an automated acquisition system before, during and after the 6-week intervention period. Also, power spectral analysis of HRV was used to assess changes in modulation of the ANS. Participants in both groups (n=14) were given lifestyle modification recommendations regarding diet, exercise and stress reduction, while participants in the training group (n=8) also completed a bilateral IHG training protocol 3 times/week at 30% maximum voluntary contraction (MVC).</p> <p> Our results demonstrate that contrary to our hypothesis, isometric exercise in combination with lifestyle modification recommendations did not result in a reduction of resting ABP or change indices of HRV. Possible explanations for these results are that unlike previous IHG training, the present study was the first to use home-based training and the small sample size of this investigation would limit our ability to identify alterations in resting ABP or HRV.</p> / Thesis / Master of Science (MSc)

This study examined the effects of isometric handgrip (IHG) training on resting blood pressure (RBP), heart rate variability (HRV) and blood pressure variability (BPV) in older adults with hypertension. Nine subjects performed four 2-minute IHG contractions at 30% maximal voluntary contraction (MVC) 3 days/week for 10 weeks and 8 subjects served as controls. Power spectral analysis (PSA) of HRV and BPV was used to assess changes in modulation of the autonomic nervous system. After training, there was a marked attenuation in arterial pressure and evidence for a shift in HR.V and BPV sympathovagal balance. There was a reduction in systolic blood pressure (156 ± 9.4 to 137 ± 7.8 mm Hg; p<0.05), diastolic blood pressure (82 ± 9.3 to 75 ± 10.9 mm Hg; N.S), mean arterial pressure (107 ± 8.53 to 96 ± 8.7 mm Hg; p<0.05) and resting heart rate (RHR) (70 ± 14.2 to 68 ± 12.1 beats/min). In addition, PSA of HRV showed a decrease in sympathetic modulation represented by low frequency (LF) area, an increase in parasympathetic modulation represented by high frequency (HF) area (p<0.05) and a decrease in LF:HF area ratio. After training, BPV PSA showed a decrease in systolic blood pressure LF area (p<0.05), an increase in HF area (p<0.05) and decrease in LF:HF area (p<0.05). Similar, but non-significant changes occurred in diastolic BPV. It is concluded that isometric training at a moderate intensity can elicit a hypotensive response and can potentially alter sympathovagal balance of HRV and BPV in older adults with hypertension. / Thesis / Master of Science (MS)

The autonomic flexibility model has proven to be a useful theoretical tool relating reductions in physiological variability found to accompany anxiety and concomitant reductions in behavioral (e.g., cognitive and emotional) flexibility. The present study aimed to extend the autonomic flexibility model through the inclusion of individual differences in the sensitivity of the independent motivational systems presumed to underlie anxiety and impulsivity, namely the behavioral inhibition and activation systems (BIS/BAS; Gray, 1994). Contrary to the predicted inverse relationship between BIS sensitivity and measures of physiological variability, findings suggest BAS sensitivity is associated with increased trait-like vagally mediated heart rate variability across diverse tasks as well as greater flexibility in responding within tasks. Numerous BIS*BAS interactions emerged as significant predictors of trait reactivity. Results are discussed in terms of the interface between (1) mesolimbic dopaminergic projections to the nucleus accumbens and (2) the network of central nervous system structures believed to play a large role in controlling peripheral physiology. / Ph. D.

Previous research has established that caregivers of children with Autism Spectrum Disorder (ASD) experience greater levels of parenting stress as a result of unique parenting demands and child problem behavior (Davis & Carter, 2008; Estes et al., 2013). Positive self-concepts, specifically parental self-efficacy (PSE), have been implicated as a buffer to stress in a number of contexts (Cieslak, Benight, & Lehman, 2008). While many studies examine parenting stress in relation to ASD, they often use parent self-report rather than objective measures in a laboratory setting. The present study aimed to further explore the role of PSE in the relationship of parental stress and ASD traits through a biological measure of stress, as well as a parent self-report within a controlled laboratory environment. Forty-two mother and child dyads participated in a validated parent-child interaction task designed to elicit a stressful experience. Mother’s heart rate (HR) and heart rate variability (HRV) were monitored as the physiological measure of stress reactivity. Mothers also self-reported on ASD traits, perceived stress-reactivity, and PSE. Results demonstrated a significant positive main effect for ASD traits on HRV reactivity, and an interaction such that the relationship between ASD traits and HRV reactivity (i.e., more emotional flexibility) was stronger in those with lower PSE. Given the low sample size and subsequent low power, results should be viewed with caution. Considerations of the context of HRV as well as implications for treatment targets and studying parental stress are explored. / Master of Science

Cardiac time intervals (CTIs) are vital indicators of cardiac health and can be estimated using a combination of electrocardiography (ECG) and seismocardiography (SCG). This study investigates the impact of SCG sensor location across the sternum on CTI estimations and heart rate variability parameters. Signal processing algorithms were developed to detect the opening and closure of heart valves on SCG for CTI calculation. A novel ECG-independent method was also developed based on template matching to determine similar parameters solely based on SCG. Comparative analysis with gold-standard methods were conducted on the SCG fiducial points, evaluating accuracy and performance. Results indicate a high overall average F1 score and correlation for all fiducial point detections. The p values revealed significant differences in SCG-derived CTI estimations across the sensor locations, highlighting the importance of sensor placement for accurate assessments. This finding underscores a fundamental step toward precise evaluation of cardiac health.

At the time of writing, stress and stress related disease have become the most common reasons for absence in the workplace in Sweden. The purpose of the work presented here is to identify and notify people managing unhealthy levels of stress. Since symptoms of mental stress manifest through functions of the Sympathetic Nervous System (SNS), they are best measured through monitoring of SNS changes and phenomena. In this study, changes in the sympathetic control of heart rate were recorded and analyzed using heart rate variability analysis and a simple runner’s heart rate sensor connected to a smartphone. Mental stress data was collected through stressful video gaming. This was compared to data from non-stressful activities, physical activity and extremely stressful activities such as public speaking events. By using the period between heartbeats and selecting features from the frequency domain, a simple machine learning algorithm could differentiate between the types of data and thus could effectively recognize mental stress. The study resulted in a collection of 100 data points, an algorithm to extract features and an application to continuously collect and classify sequences of heart periods. It also revealed an interesting relationship in the data between different subjects. The fact that continuous stress monitoring can be achieved using minimally intrusive sensors is the greatest benefit of these results, especially when connsidering its potential value in the identification and prevention of stress related disease.