Overview
Physiological arousal is the body's state of heightened activation in which the autonomic nervous system, especially its sympathetic branch, raises measures such as heart rate, respiration, skin conductance, and muscle tension in response to a stimulus or stressor. It is a central concept in psychophysiology and stress research because it links emotional and cognitive states to measurable bodily changes, and because chronic or excessive arousal is implicated in anxiety, post-traumatic stress, and other stress-related conditions. Key aspects include the distinction between sympathetic activation ("fight or flight") and parasympathetic recovery ("rest and digest"), the role of brain networks that mediate the stress response, and the ways arousal can be measured, modulated, or down-regulated through behavioral and somatosensory interventions. Understanding physiological arousal helps clinicians and researchers interpret stress reactions and evaluate techniques aimed at reducing them. Related open-access research in this collection examines how non-invasive somatosensory stimulation can modulate the brain networks responsible for sympathetic arousal and lower self-reported emotional and bodily stress.