In my book Willpower Condensed, I discussed three physiological correlates of willpower, three ways in which self-control is biologically grounded in the body:
- When your parasympathetic nervous system is active, it puts your body in “pause and plan” mode so that you can control yourself.
- Heart rate variability rises as you control yourself, and the higher its baseline, the greater is your willpower.
- Neural activity in the anterior cingulate and prefrontal cortex increases during self-regulatory efforts.
Recently, a new meta-study (Zahn et al., 2016) looked into #2 more closely, analyzing the relationship between heart rate variability and self-control based on 26 different studies. Although the meta-analysis did find a positive effect, the authors suggest that this effect may result from a publication bias. This would mean that heart rate variability does not actually reflect willpower; it is just that studies with such a negative outcome were less likely to be published and are therefore underrepresented in the scientific literature.
As Laborde and Mosley (2016) pointed out, however, heart rate variability is a complex phenomenon. According to our current theoretical understanding, not all parameters of this variable relate to self-control. Not heart rate variability in general reflects willpower, but vagal tone in particular.
The vagus nerve is a nerve emanating from the brain (cranial nerve) that interfaces with the parasympathetic nervous system’s control of the heart, lungs, and intestines. Its activity is called “vagal tone.” When you breathe in, you suppress vagal activity: your vagal tone decreases, your heart rate increases. Conversely, when you breathe out, your vagal tone increases and your heart rate decreases. This mechanism, called “respiratory sinus arrhythmia,” is a naturally occurring, breath-dependent variation in your heart rate. Unlike vagal tone, respiratory sinus arrhythmia can be measured directly as a certain frequency of heart rate variability—typically high, sometimes low frequency, depending on breathing rate. This is what should be linked to self-control.
In conclusion, although overall heart rate variability might not be a biological correlate of willpower, vagal tone, measured as respiratory sinus arrhythmia, can well be. This suggests once again that by controlling your breath, you can control your self.
Laborde, S., Mosley, E. (2016). Commentary: Heart rate variability and self-control—A meta-analysis. Frontiers in Psychology, doi: 10.3389/fpsyg.2016.00653.
Zahn, D., Adams, J., Krohn, J., Wenzel, M., Mann, C. G., Gomille, L. K., Jacobi-Scherbening, V., Kubiak, T. (2016). Heart rate variability and self-control—A meta-analysis. Biological Psychology 115, pp. 9-26, doi: 10.1016/j.biopsycho.2015.12.007.