Self-esteem fluctuations and cardiac vagal control in everyday life.

It has been proposed that self-esteem buffers threat-responding. The same effect is ascribed to the vagus nerve, which is a primary nerve of the parasympathetic nervous system. Consequently, it has been suggested that self-esteem and cardiac vagal tone are interconnected on a trait, as well as on a state, level. In this study, we examined the relationship of vagal cardiac control and self-esteem fluctuations across a single day using ecological momentary assessment. Eighty-four participants were recruited, and self-esteem, negative affect, and vagal tone were recorded throughout a 22-hour period. Men provided higher self-esteem ratings than women, but the negative relationship between self-esteem and negative affect was stronger in women. Moreover, controlling for potential confounds (e.g., age, BMI, depressive symptoms, smoking status, regular physical activity), we observed that for men, self-esteem was significantly positively associated with cardiac vagal tone, whereas for women it was not. These findings suggest that the relationship between self-esteem and vagal innervation of the heart during daily life is sex-specific and might involve different central-autonomic pathways for men and women, respectively.