On Singing
About:
"Singing. Polvagal Theory interprets singing as a neural exercise of the social engagement system. Singing requires slow exhalations, while controlling the muscles of the face and head to produce the modulated vocalizations that we recognize as vocal music. The slow exhalations calm autonomic state by increasing the impact of ventral vagal pathways on the heart. During the exhalation phase of breathing, vagal motor fibers send an inhibitory signal (i.e., vagal brake) to the heart's pacemaker that slows heart rate. During the inhalation phase of breathing the vagal influence to the heart is diminished and heart rate increases. Singing requires longer exhalations relative to inhalations, which promotes a vagal mediated calm physiological state. The process of singing couples the exercise of turning on and off the 'vagal brake' with the exercise of the neural regulation of the muscles of the face and head, including facial muscles, middle ear muscles for listening, and muscles of the larynx and pharynx for vocal intonation. Thus, singing provides an opportunity to exercise the entire integrated social engagement system. Chants, oral readings, and playing a musical instrument would also provide opportunities to exercise the system."
Porges, Stephen W.. The Pocket Guide to the Polyvagal Theory: The Transformative Power of Feeling Safe (Norton Series on Interpersonal Neurobiology) (pp. 25-26). W. W. Norton & Company. Kindle Edition.