The autonomic nervous system is the portion of the nervous system that controls involuntary body processes such as heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is divided into two parts: the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic nervous system is responsible for the "fight-or-flight" response. This is the body's natural reaction to a perceived threat, and results in an increase in heart rate, blood pressure, and respiration, as well as a release of adrenaline and cortisol.
On the other hand, the parasympathetic nervous system is responsible for the "rest-and-digest" or "feed-and-breed" response. This is when the body is at rest and focused on functions such as digesting food and reproducing.
The autonomic nervous system plays an important role in how we respond to trauma. When we experience a traumatic event, our sympathetic nervous system kicks into gear in order to help us deal with the stressor. This can often result in symptoms such as hypervigilance, insomnia, anxiety, and irritability.
In some cases, however, the autonomic nervous system can become dysregulated. This means that it no longer responds appropriately to stressors. For example, someone who has experienced trauma may have a low heart rate even when they're not in danger. Or they may have trouble sleeping even when they're not under stress. When this happens, it can be difficult for people to function.
There are several theories about why this might happen. One theory suggests that it's a way for our bodies to protect us from further trauma by numbing us to potential threats. Another theory suggests that it's a way for our bodies to conserve energy so that we can deal with the aftermath of trauma. Regardless of why it happens, dysregulation of the autonomic nervous system can be extremely debilitating. Trauma-informed interventions help people manage their symptoms and assist with daily living.