Background: Unfavourable psychogenic factors may increase the risk of cardiovascular outcomes. We have previously shown that mental stress has an acute detrimental effect on aortic stiffness, which is a determinant of cardiovascular performance and predictor of the corresponding risk. Aim of the present study was to evaluate the impact of laughter on aortic elastic properties.

Methods: Thirteen healthy volunteers (age 27±5 years) were enrolled in the study, which was carried out on two separate arms, one with viewing of a 30 minutes long segment of a comedy, and one with sham-procedure, according to a randomized, single-blind, cross-over design. During the sham-procedure arm the subjects rested for 30 minutes and nothing was projected. Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness using an automated, non-invasive device (Complior^®), before (baseline) and shortly after the movie.

Results: No significant change in blood pressure and heart rate was observed after watching the comedy. However, comedy led to a significant decrease in PWV (decrease by 0.39m/s compared to the sham-procedure, P < 0.05, figure), indicating a decrease in aortic stiffness.

Conclusions: This study shows for the first time that laughter has a favorable effect on aortic elastic properties. This finding provides valuable insights into the effect of laughter on the cardiovascular system, expanding the ways in which aortic stiffness can be decreased beyond pharmacological approaches.