Effects of Trauma on the Nervous System
Key Terms Defined
To understand the trauma response, it is helpful to know these core nervous system concepts:
Parasympathetic Nervous System: The parasympathetic nervous system (PSNS) or rest-and-digest system, is part of the autonomic nervous system, along with the sympathetic nervous system. Located between the brain and spinal cord, the PSNS is tasked with saving the body’s energy by slowing the heart rate and increasing the activity of the intestines and glands during periods of rest. It also relaxes the sphincter muscles in the gastrointestinal system.
Sympathetic Nervous System: The sympathetic nervous system or fight-flight mode is responsible for rapid activation of the body’s emergency survival response in the face of actual or perceived threat, emotional or physiological overwhelm, or traumatic memories, reminders and conditioned reactions.
Explicit Memory: Explicit memory refers to the conscious retrieval of past information or experiences. This is when the individual is in a situation that triggers them to remember a direct previous experience.
Implicit Memory: Implicit memory refers to an unintentional or unconscious form of retrieval. This is when the individual is in a situation that triggers them to react unintentionally to the situation without making any direct connection to a previous experience.
False Memory: False memory refers to when the nervous system distorts the actual memory to create a half true scenario to help the individual bypass the actual traumatic experiences.
Trauma is not just an emotional event; it is a physiological event that fundamentally alters the way your nervous system responds to the world. Understanding this mechanism is the first step toward healing.
Outside the Window of Tolerance
During a traumatic experience, the nervous system is pushed far outside its “Window of tolerance”—the optimal zone where we can regulate emotions and think clearly.
When this happens, the system shifts into dysregulation:
Hyperarousal (SNS Overactivation): When the accelerator is stuck, this leads to states like anxiety, panic, hypervigilance, and irritability.
Hyperarousal (PSNS Shutdown): When the system shuts down to protect itself (dorsal vagal state), this leads to states like depression, numbness, disconnection, and disassociation.
Memory and Self Protection
Trauma often causes a disconnect between the conscious (explicit) and unconscious (implicit) memories. This leads to the formation of:
False Memory: This occurs when the nervous system distorts the actual memory to create a half-true scenario, often as a protective measure to bypass or soften the reality of the deeply traumatic experience.
The Long-Term Impact
This conditioned state of fear, confusion, and dysregulation can continue long after the traumatic event has ended. The body remains on high alert, creating persistent implicit memories that are often triggered by seemingly unrelated words, objects, smells, or people in adulthood.
Understanding that your system is dysregulated—not broken—is the fundamental insight that opens the door to healing.
