文摘
Normal breathing consists of considerable correlated variability (parameters of subsequent breaths are correlated) and some random variability. Emotional and attentive states alter normal breathing variability, which can be restored by a sigh. The present study aimed to investigate the effects of mental arithmetic and sustained attention on respiratory variability. In addition, the effect of a spontaneous sigh following both conditions was examined, compared to an instructed sigh and a control maneuver. Mental arithmetic and sustained attention were characterized by decreased correlated and total breathing variability, respectively. A spontaneous sigh restored correlated variability. An instructed sigh restored correlated variability following mental arithmetic, and increased total variability following sustained attention. These results suggest that a spontaneous sigh and an instructed sigh, when physiologically appropriate, restore respiratory variability influenced by stress or attention.