Using Heart Rate Variability as a Bridge Between Trauma & Health
Posted on February 11, 2020
In this post, I want to explore what someone’s Heart Rate Variability (HRV) tells us about the impact of trauma and stress on their mind and body. In the next few posts, I’ll explore how HRV helps us quantify wellness, healing and post-traumatic growth. One of the things that got me really excited about HRV was how a simple measure tells us so much about psychological, emotional, cognitive, and social health.
Most of those reading this post understand trauma’s impact on the brain and nervous system and the science that shows how the brains of those with untreated complex trauma (high ACE score) operate differently. While it might seem odd, the best way to measure this impact (assuming you don’t have regular access to expensive brain-scanning technology) is through the health of the autonomic nervous system as measured through variation of time between heartbeats. HRV provides us a window to access the effects of trauma on the biological health and functioning of those we are trying to help.
Let’s explore the connections between the brain, heart, and trauma. During intense stress and trauma, one of two systems in the body gets activated allowing energy to support behaviors needed to survive the traumatic experience. Initially, in most people, the sympathetic nervous system is activated sending energy normally used by the brain to the body for flight (getting distance between the person and cause of stress or trauma) or, if one cannot flee, fight (attacking the sources of trauma). If these systems fail to reestablish safety, the dorsal branch of the vagus nerve (a part of our parasympathetic nervous system) activates the freeze response where most systems in the body slow down dramatically and often leads to dissociation or disconnection from reality.
People who experience repeated trauma or live in constant stress or threat rely heavily on the sympathetic response that strengthens these systems (including the amygdala). This reliance on the sympathetic response often results in behavior and thinking that often get diagnosed as anxiety disorders, anger control issues, or post-traumatic stress disorder. Others, especially those experiencing repeated physical or sexual abuse where they have no power or ability to run or fight, rely heavily on the dorsal vagal besides resulting in dissociative disorders, over activation of the dorsal branch results in depressive symptoms.
This traumatized nervous system is associated with less activity in the prefrontal cortex, hippocampus and other areas of the brain responsible for emotional regulation, memory, and cognitive functioning. How does this impact our heart and HRV? To understand the connection, we need to include one additional system central to health and wellness.
Our respiratory system syncs with our heart through a process called respiratory sinus arrhythmia (RSA). When we inhale, we activate our sympathetic nervous system increasing our heart rate. On the exhale our vagus nerve activates slowing our heart rate. A healthy nervous system (and body) reflects a balance between our sympathetic nervous system and dorsal vagal nerve and a low resting heart rate. The more robust the system the more variation between each heartbeat and higher HRV score.
Plenty of research demonstrates that those with high ACEs who have not received treatment have lower HRV scores. As a reflection of an unhealthy nervous system, low HRV correlates with the same diseases and social problems found in the ACE Study. While I always find it interesting when medical science supports ACE research, we could shrug off HRV if all it did was support that high ACE scores negatively impact people’s health and biology.
The exciting news about HRV is that it does not just give us another measure of the devastating impact of trauma. While someone with a high ACE score will likely score low on HRV at baseline, improved HRV against that baseline shows our interventions are helping to heal their nervous system resulting in increased resiliency, emotional regulation, social engagement, and other crucial components of post-traumatic growth. I believe HRV opens up a whole new way to think about healing, a topic I want to explore more in future posts.