Breath slower, be smarter? The effects of slow paced breathing on cognitive executive functioning

Slow paced breathing has been found to increase cardiac vagal tone, creating a resonance state in the cardiovascular system when the individual breathes at 6 cpm. According to the neurovisceral integration model, cardiac vagal tone is positively associated with executive performance (Thayer, Hansen, Saus-Rose, & Johnsen, 2009). However, it is still unknown whether an increase in cardiac vagal tone provoked by slow paced breathing would result in an increase of executive performance. Moreover, the most optimal inhalation/exhalation ratio and the duration of the effects of slow paced breathing are still unknown. Therefore the aim of this research project was twofold: first to clarify the most optimal way to realize slow paced breathing as well as the duration of its effects, and second to investigate its influence on executive performance. This research project comprised of five experiments. Cardiac vagal tone was assessed through heart rate variability and more specifically with the root mean square of the successive differences (RMSSD). Respiratory rate was controlled for in all analyses. The first two experiments aimed to investigate the parameters of slow paced breathing and the duration of its effects. Experiment 1 (N=63) showed that the best ratio was obtained with longer exhalation and shorter inhalation, provoking a higher activation of the vagal brake. Experiment 2 (N = 15) showed that the effects of slow paced breathing on cardiac vagal tone lasted at least 1h, with a higher increase in comparison to a video control condition. Regarding the second aim, we investigated the effects of slow paced breathing on the three core executive functions (Diamond, 2012): inhibition (experiment 3), working memory (experiment 4), and cognitive flexibility (experiment 5). Based on similar within-subject designs (N = 30 for experiments 3, 4, 5), we found that performance on all executive functions increased after slow paced breathing in comparison to a video control condition, and RMSSD was found to mediate this increase. In summary, this research project showed that slow paced breathing can increase executive performance through vagal tone increase, based on the most optimal inhalation/exhalation ratio, and that those effects may last at least for 1h. Given the protective properties of a higher vagal tone for health and against stress (Thayer et al., 2009), slow paced breathing may play a very important role regarding health on a larger society scale. Diamond, A. (2012). Executive Functions. Annu Rev Psychol. doi: 10.1146/annurev-psych-113011-143750 Thayer, J. F., Hansen, A. L., Saus-Rose, E., & Johnsen, B. H. (2009). Heart rate variability, prefrontal neural function, and cognitive performance: the neurovisceral integration perspective on self-regulation, adaptation, and health. Annals of Behavioral Medicine, 37, 141-153. doi: 10.1007/s12160-009-9101-z