Experimentally induced mood changes and simultaneously changing heart rate variability (HRV)

Objective To investigate the relationship between rapidly changing emotional states and simultaneously measured heart rate variability (HRV). Methods Eighty-two healthy subjects underwent a mood induction procedure while ECG recordings were made. The subjects were asked to look at an image for 30 s and then instructed to visualize the image again with closed eyes for 1 min. RR intervals were calculated as the time between two adjacent R-peaks. HRV was calculated by taking the square root of the mean absolute differences between RR intervals for each 10-s segment. This value was then logarithmically transformed. Results Following a series of validation analyses, the relationship between mood changes and HRV was assessed. A first positively loaded image corresponded with higher levels of HRV compared to a first negatively loaded image. For the second image of opposite emotional valence, no reversal of HRV could be demonstrated. In contrast, the HRV level measured during the first image continued during the visualization phase of the second image. Conclusion This study provides evidence that experimentally manipulated mood covaries with HRV. However, when mood states change rapidly, the relationship with HRV is not detectable. Several post-hoc explanations are provided. Possible implications for clinical practice are discussed.