Dr. Van Der Kolk says that Heart Rate Variability (or HRV) plays a crucial role in our response to trauma. Healthy people typically have high HRV, which means their pulse fluctuates rapidly in response to external stimuli. This reflects a well-functioning nervous system which is able to change in balance with our environment. High-HRV individuals can moderate their emotions by controlling their breathing, allowing them to stay calm and engaged in the present moment.
In contrast, survivors like Sarah tend to be stuck in their traumatic past, taking rapid short breaths out of worry that their trauma may return–even when the threat has long subsided. This causes poor HRV, a state in which changes in breathing take much longer to affect emotion. Poor HRV has negative effects on thinking and feeling, and it also contributes to heart disease and cancer. Luckily, techniques exist which allow us to regain some control over our reactions to triggering stimuli.