A meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health.
Thayer JF, Ahs F, Fredrikson M, Sollers JJ, Wager TD. A meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health. Neurosci Biobehav Rev. 2012 Feb; 36(2):747-56.