Endocrine and cardiovascular responses to a series of graded physical and psychological stress stimuli in healthy volunteers

Preliminary analysis of physiological changes of nursing students during training

Long-term exposure to stress has been associated with chronic diseases, depression, and immune disorders. The precise detection and assessment of stress depends on personalized physiological monitoring and assessment of influence of personal and workplace factors We monitored nursing students during training on a high fidelity simulator in the Real-time Physiological Monitoring Lab at the University of Alabama in Huntsville. In this paper we present the preliminary results of this pilot study. A total of 14 participants were recorded: 12 female and 2 male subjects, 23-46 years old with an average age of 32.8 years. We analyzed heart rate, Heart Rate Variability (HRV), respiration, and physical activity. The results indicate significant strain on subjects during simulation: heart rate increased 16.7%, from 82.8 to 96.6 bpm (p<0.001), falling to a slightly increased level after the training session (84.9 bpm); Root Mean Square of Successive RR Differences (RMSSD) decreased from 38.9 ms to 37.7 ms; the breathing rate increased during the simulation from 16.9 to 17.7 breaths/min. Distractions also significantly influenced physiological parameters: the first telephone call increased heart rate on average 9 bpm (p<0.001), while the second call increased heart rate 8.6 bpm (p<0.001). The simulated patient-related events created even more prominent response; the average heart rate increased 17.4 bpm (p<0.001) at the onset of "patient in crisis" event. Real-time wearable monitoring may provide assessment of occupational stress.

The Effects of Mental Arithmetic Strain on Behavioral and Physiological Responses

Everyday activities require different levels of mental load depending on both external and internal task demands, and the resulting strain is likely to drastically influence the forthcoming performance. In this study, we aimed to determine how objective and subjective task constraints may respectively impact strain and performance. Thirty participants, recruited for their affinity or avoidance for mental arithmetic, were confronted with calculations of varying difficulty. Data showed that Reaction Times (RTs), as well as electrodermal (EDR) and heart rate (HR) response durations increased along with task difficulty and performance decrement. Good performance elicited weaker sympathetic involvement, attesting that positive emotions are likely to elicit less strain than negative emotions. The “approach” group exhibited longer electrodermal responses than the “avoidance” group, especially when performing difficult computations. The “approach” group also showed increased EDR duration along with increased RT, while the “avoidance” group exhibited decreased EDR duration along with increased RT. Therefore, individuals with mental arithmetic affinity might be more involved than those with avoidance. Finally, HR deceleration prior to mental arithmetic did not vary as a function of the independent variables, thus meaning that attention increased to the same extent regardless of the experimental condition. Thus, the resulting strain depends on task difficulty, response accuracy, and group membership, the most sensitive physiological indices being EDR duration and HR response duration.

Towards mental stress detection using wearable physiological sensors

Early mental stress detection can prevent many stress related health problems. This study aimed at using a wearable sensor system to measure physiological signals and detect mental stress. Three different stress conditions were presented to a healthy subject group. During the procedure, ECG, respiration, skin conductance, and EMG of the trapezius muscles were recorded. In total, 19 physiological features were calculated from these signals. After normalization of the feature values and analysis of correlations among these features, a subset of 9 features was selected for further analysis. Principal component analysis reduced these 9 features to 7 principal components (PCs). Using these PCs and different classifiers, a consistent classification accuracy between stress and non stress conditions of almost 80% was found. This suggests that a promising feature subset was found for future development of a personalized stress monitor.

Sex differences in cortisol response to noxious stress

OBJECTIVES

Evidence has accumulated that men and women show different responses to noxious stimuli, with women exhibiting greater sensitivity to pain than men. Data concerning sex differences in cortisol response patterns have revealed inconsistent results so far. The purpose of the present study was to examine sex differences in subjective pain and cortisol response to a noxious stressor.

METHODS

Seventy-six subjects (39 male and 37 female) were investigated by a modification of the cold pressor test that consisted of intermittent immersion of the hand into ice water (plunge test, PT). The PT was conducted twice, in consecutive trials, to guarantee a sufficient exposure to the noxious stressor for eliciting cortisol responses. In each trial, tolerance time and pain ratings visual analog scale (VAS) were assessed. Seven saliva samples (c1-c7) were collected to determine cortisol levels at baseline (c1-c2), directly before (c3) and 20 minutes after noxious stress (c4), and during recovery period (c5-c7).

RESULTS

We found no significant sex differences in tolerance time in trial 1, but highly significant differences in tolerance time in trial 2, with higher tolerance times in men. No significant sex differences were found for the VAS ratings of pain intensity and unpleasantness in the 2 trials. In contrast, a significantly larger cortisol increase in men was observed compared with women. Analysis of covariance revealed that this result could not be attributed to sex differences in cortisol level at baseline and in tolerance time.

DISCUSSION

The present study demonstrates that men show a larger cortisol response to a noxious stressor than women that is not attributable to sex differences in subjective pain. The conclusion of a causal relation between larger cortisol responses and higher pain tolerance thresholds in men is tempting but yet speculative.

Physiological and emotional response to psychological stressors in psychiatric and psychosomatic disorders

Deviations from emotional and physiological homeostasis in humans occur under episodic, chronic, or traumatic stress experiences. These dysregulations can provoke emotional and physical disturbances that may result in stress-related psychiatric or psychosomatic disorders. This brief review discusses a variety of both naturally occurring and experimental stressors and the complexity of intervening variables on cardiovascular and hormonal dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis. In addition to the type, intensity, and duration of the stressor, subject variables such as dispositional factors (e.g., age and sex), personality traits, and coping styles are considered. Finally, emotional and physiological stress responses to naturally occurring stressors and psychological challenge tests in depressed patients and anxiety disorder patients are presented and discussed. Stressors in humans induce emotional arousal, which leads to physiological activation of the central nervous system, an increase of hormones of the HPA axis, and coping reactions on the psychological and behavioral level. Depending on the type, intensity, and duration of the stressor, on personal and psychosocial resources of the individual, stressful situations may provoke emotional and physical disturbances. These dysfunctions may result in psychosomatic or psychiatric disorders. The following brief review intends to discuss a variety of stressors that have been examined in humans in order to gain insight into the complex relationship between physiological and behavioral stress reactions and the occurrence or maintenance of stress related psychosomatic and psychiatric disorders.