IL6 and medical procedure: Low vagal tone indicated by vagally mediated HRV was associated with elevated plasma levels of IL-6 and soluble tissue factor in healthy middle-aged men and women (von Känel et al., 2007), and in a study of healthy subjects from a sub-sample of the Coronary Artery Risk Development in Young Adults (CARDIA) study, vagally mediated HRV was strongly and inversely related to IL-6 and CRP levels (Sloan et al., 2007).