Excessive talkativeness can cause a range of health impacts, including chronic disease: cancer, heart disease, diabetes, obesity.
Furthermore, additional negative effects of modern speaking skills include mouth breathing for inhalations and thoracic breathing, using the upper chest.Both these factors further reduce oxygen delivery to body cells. Continuous speaking resets the breathing center to lower arterial and brain CO2 levels promoting hyperventilation, tissue hypoxia. Average initial end-tidal CO2 pressure of these healthy young American men was almost 38 mm Hg. After 10 minutes of speaking it dropped to about 31 mm Hg. 10 min of speaking reduced their brain oxygenation about two times. Long conversations and excessive talkativeness can thereby lead to dizziness, light-headedness, loss of concentration, emotional instability, muscular tension, abnormal posture and other negative effects
Hoit JD & Lohmeier HL, Influence of continuous speaking on ventilation 43(5): 1240-1251
movements of chest during breathing right: exhalation left: breath