The effects of sighing on the cardiovascular system

•A single sigh strongly affects a number of cardiovascular functions.•Rhythmical sighing at 0.02Hz imposes high-amplitude oscillations in functions.•Imposed oscillations can be used to study the mechanisms that regulate functions.•A sigh may be an acute respiratory maneuver to mitigate stress via baroreflex mechanism.•High-amplitude oscillations imposed by rhythmical sighing may be clinically useful. Elicitation of high-amplitude oscillations in the cardiovascular system may serve to dampen psychophysiological reactivity to emotional and cognitive loading. Prior work has used paced breathing to impose clinically valuable high-amplitude ∼0.1Hz oscillations. In this study, we investigated whether rhythmical sighing could likewise produce high-amplitude cardiovascular oscillations in the very low frequency range (0.003–0.05Hz). ECG, respiration, skin conductance, and beat-to-beat blood pressure were collected in 24 healthy participants during baseline, 0.1Hz paced breathing, and 0.02Hz paced sighing (1 sigh every 50s, with normal breathing interspersed). Results showed that each sigh elicited a strong, well-defined reaction in the cardiovascular system. This reaction did not habituate when participants repeatedly sighed for 8.5min. The result was a high-amplitude 0.02Hz oscillation in multiple cardiovascular parameters. Thus, paced sighing is a reliable method for imposing very low frequency oscillations in the cardiovascular system, which has research and clinical implications that warrant further study.