Emotion, sighing, and respiratory variability.

How dimensions of emotion affect respiratory regulation assessed by respiratory variability and sighing is unknown. The present studies aimed to investigate the effects of emotional valence and arousal on respiratory variability and sigh rate. Within subjects, emotions were induced by picture viewing in a first experiment, and script-driven mental imagery in a second experiment. Respiration was measured throughout the experiment, while valence, arousal, and dominance ratings were assessed after each trial. Negative and/or high-arousal emotions increased sigh rates and respiratory variability during picture viewing and imagery. Only depression imagery, however, decreased correlated variability (and only in minute ventilation). Fear imagery particularly increased variability in end-tidal carbon dioxide and expiratory time. These findings show that dimensions of emotion importantly influence respiratory regulation.