“…Psychosocial factors, such as stressful life events (Pieper et al, 2010; van Ockenburg et al, 2015), general stress (Kang et al, 2004; Brosschot et al, 2006; Chandola et al, 2010; Chida and Steptoe, 2010), hostility (Virtanen et al, 2003; Chida and Steptoe, 2009), depression (Stein et al, 2000; Gehi et al, 2005; Ha et al, 2015; Sgoifo et al, 2015) and anxiety (Friedman and Thayer, 1998; Alvares et al, 2013) have all been found to be associated with lowered HRV. In addition, individuals with stronger emotion regulation (Thayer et al, 2009; Patron et al, 2014; Gillie et al, 2015) and adaptive coping strategies have been shown to have higher levels of HRV (Appelhans and Luecken, 2008; Thayer and Lane, 2009). Moreover, low cardiac vagal tone, as reflected in the square root of the mean of the squared differences between adjacent normal RR intervals (rMSSD), is associated with poor self-regulation and lack of behavioral flexibility (Porges, 1992).…”