Nervous System Foundations in Somatic EMDR: A Clinical Framework
- 22 hours ago
- 7 min read
Trauma changes the nervous system's baseline. And that baseline determines everything about how our clients respond to EMDR processing.
You've likely experienced this: the client who processes smoothly, SUDs dropping predictably, adaptive information emerging naturally. And then the client who can't tolerate bilateral stimulation at all. Who dissociates when you introduce eye movements. Whose window of tolerance is so narrow that even resourcing feels destabilizing.
The difference often isn't in the trauma itself—it's in the nervous system's capacity to engage with processing.
Understanding Polyvagal Theory isn't just theoretical knowledge for somatic EMDR practitioners. It's the foundation for recognizing when clients have the nervous system capacity for trauma work and when stabilization needs to come first.
The Polyvagal Foundation: Three States, Not Two
Dr. Stephen Porges's Polyvagal Theory revolutionized our understanding of the autonomic nervous system by revealing that we don't operate in simple binary states of "calm" versus "activated." We have three distinct neurobiological states, each with its own behavioral and relational signature:
Ventral Vagal (Social Engagement System):
The state of safety and connection. The nervous system signals that the environment is safe enough for social engagement, rest, digestion, growth. Clients in this state can reflect, process, integrate. Their faces are expressive, voices modulated, bodies relatively regulated. This is where adaptive information processing can occur most efficiently.
Sympathetic (Mobilization): The fight-or-flight response. Energy mobilizes for action—heart rate increases, muscles tense, breathing accelerates, cortisol and adrenaline surge. In acute activation, this is adaptive. In chronic activation, it's the hypervigilance, reactivity, and anxiety we see in so many trauma survivors. Clients may still be able to engage with processing if activation isn't extreme, but careful titration becomes essential.
Dorsal Vagal (Immobilization): The shutdown response to overwhelming threat. When fight or flight aren't viable options, the nervous system collapses into immobilization—numbing, dissociation, flat affect, cognitive fog, a sense of being outside oneself. This is where processing becomes impossible. A client in dorsal vagal shutdown cannot integrate new information. They're in survival, not engagement.
The clinical skill is recognizing which state your client is inhabiting—and whether that state has the capacity for the work you're proposing.
Neuroception: The Body's Pre-Conscious Assessment
Here's what complicates treatment: the nervous system doesn't wait for conscious evaluation before it responds.
Porges calls this neuroception—the subconscious detection of safety or danger cues. It's happening constantly, beneath awareness, faster than thought. A tone of voice. A facial expression. The way light falls in the therapy room. The therapist's proximity or posture.
The nervous system is scanning, assessing, making survival-based decisions before the client's prefrontal cortex has processed anything consciously.
This is why some clients react to EMDR in ways that seem disproportionate to the actual intervention. It's not the bilateral stimulation itself that's threatening—it's what their nervous system detected: Eye contact that feels too direct. A hand movement that registers as danger. The therapist's emotional state bleeding through despite professional composure.
For trauma survivors, neuroception is often biased toward threat detection. What neurotypical nervous systems read as neutral, traumatized nervous systems read as dangerous. What should signal safety doesn't register as safe at all.
This is the clinical reality we're working with in somatic EMDR: a nervous system that may perceive the therapy itself as threatening, even when the client consciously wants to engage.
The Vagus Nerve: The Body's Bidirectional Highway
The vagus nerve is the primary pathway of the parasympathetic nervous system, running from the brainstem through the face, throat, heart, lungs, and digestive system. It's the mechanism through which the nervous system communicates safety or threat throughout the body.
But here's what matters clinically: the vagus nerve operates bidirectionally. Information flows from the brain to the body (top-down regulation) and from the body to the brain (bottom-up signaling).
This is why somatic interventions work. When we help clients engage the ventral vagal system through breath, movement, or relational attunement, we're not just managing symptoms—we're literally signaling safety through the vagus nerve, which then influences brain state, emotional regulation, and cognitive capacity.
In EMDR, bilateral stimulation itself engages the vagus nerve. But if the client's baseline vagal tone is dysregulated—if they're stuck in sympathetic hyperarousal or dorsal shutdown—the bilateral stimulation may not facilitate adaptive information processing. It may be destabilizing.
Vagal Tone and Nervous System Processing Capacity
Vagal tone refers to the flexibility and responsiveness of the vagus nerve. High vagal tone means the nervous system can shift states appropriately: activate when needed, return to baseline efficiently, respond proportionally to stress.
Low vagal tone means the nervous system is rigid—stuck in chronic activation, chronic shutdown, or oscillating unpredictably between the two without the capacity to stabilize.
Here's what this means clinically:
Clients with healthy vagal tone can typically engage with trauma processing. They can tolerate activation, return to baseline between sets, and integrate adaptive information. Processing feels efficient.
Clients with compromised vagal tone struggle. They can't hold dual awareness. Bilateral stimulation feels overwhelming rather than organizing. They dissociate, dysregulate, or become flooded. Resourcing itself may be activating because their nervous system can't tolerate the shift.
These aren't treatment-resistant clients. They're clients whose nervous systems aren't yet regulated enough to engage with trauma processing.
The clinical question becomes: How much nervous system stabilization is required before trauma work becomes viable? And recognizing that for some clients, that stabilization is months or years of work, not weeks.
Recognizing Nervous System State in Session
This is where clinical observation becomes essential. You're assessing nervous system state throughout every session—not just during formal check-ins, but continuously.
Ventral vagal indicators:
Facial expressiveness, eye contact that feels comfortable (not forced or avoided)
Voice modulation, prosody, capacity for humor or lightness
Body language that's open or relaxed, even when discussing difficult material
Ability to reflect, consider multiple perspectives, access curiosity
Physiological regulation: steady breathing, stable heart rate, muscle tone that's neither rigid nor collapsed
Sympathetic activation indicators:
Hypervigilance, scanning the room, startled responses
Muscle tension, restlessness, fidgeting, difficulty staying seated
Rapid or shallow breathing, elevated heart rate
Irritability, reactivity, pressured speech
Difficulty concentrating, mind racing, hyperawareness of threat cues
Dorsal vagal shutdown indicators:
Flat affect, monotone voice, minimal facial expression
Dissociation, cognitive fog, "spacey" presentation
Low energy, slowed movement, difficulty making eye contact
Emotional numbness, disconnection from body sensations
Reports of feeling "not here," watching from outside, or time distortion
The clinical skill is recognizing when a client shifts states during session—and adjusting accordingly.
Why This Matters for Midlife and Complex Trauma
Midlife clients often present with a specific nervous system profile that requires understanding Polyvagal Theory at a deeper level.
For many—particularly women navigating perimenopause and menopause—the neurobiological changes of this transition destabilize previously functional nervous system regulation. Estrogen fluctuations affect vagal tone. Stress response systems that were compensated become dysregulated. The body that held trauma in containment for decades suddenly releases it.
And this is happening at the same time many midlife clients are managing aging parents, ambiguous loss, anticipatory grief, and the resurfacing of historical trauma that their nervous systems can no longer suppress.
The result: clients who appear high-functioning but whose nervous systems are barely holding together. Who can manage the external demands of life but have no capacity left for trauma processing. Whose baseline state oscillates between sympathetic hypervigilance (managing everyone and everything) and dorsal shutdown (collapsing when alone).
These clients need nervous system stabilization as foundational work. And that's not a failure of treatment—it's appropriate clinical recognition of nervous system capacity.
AIP and the Nervous System
Adaptive Information Processing—the theoretical foundation of EMDR—assumes the brain's innate capacity to process and integrate traumatic material when given the right conditions. But those "right conditions" include a nervous system that can engage with the process.
If the nervous system is stuck in survival states—chronic sympathetic activation or dorsal vagal shutdown—the adaptive processing system cannot function as intended. The brain cannot access the networks needed for integration. The bilateral stimulation becomes noise, not signal.
Understanding Polyvagal Theory helps us recognize when the conditions for AIP are present and when they're not. When the nervous system needs stabilization before processing becomes possible.
This isn't about abandoning EMDR. It's about recognizing that nervous system regulation is the foundation upon which all trauma processing rests.
The Art of Clinical Discernment
The skill that develops over time is knowing when the nervous system is ready and when it's not.
It's recognizing that the client who seems engaged and motivated but dissociates during bilateral stimulation isn't resistant. Their dorsal vagal system is protecting them from overwhelm.
It's understanding that the client who can't complete resourcing exercises without becoming more anxious isn't "doing it wrong." Their sympathetic system interprets the attempt to relax as dangerous—a loss of necessary vigilance.
It's accepting that some clients will need extensive nervous system stabilization before they can engage with trauma targets. And that's legitimate clinical work.
Polyvagal Theory gives us the framework to make these clinical decisions with confidence rather than doubt. To trust that pacing is sometimes the most important intervention we can offer.
If This Resonates
If you're working with clients whose nervous systems seem to resist processing, if you're wondering how to assess nervous system capacity more accurately, if you're struggling to differentiate between nervous system dysregulation and other clinical presentations—this framework matters.
Understanding how trauma lives in the nervous system and how the nervous system responds to therapeutic intervention transforms clinical judgment.
It's the difference between pushing through and pacing skillfully. Between misreading shutdown as disengagement and recognizing it as a dorsal vagal response. Between adding more interventions and recognizing that stabilization is the intervention.
Somatic EMDR asks us to work with the body's wisdom, not override it. Polyvagal Theory gives us the map.
If you're interested in exploring how Polyvagal Theory applies to your clinical work with complex trauma and midlife presentations, I offer consultation for EMDR clinicians.
About
Julie Cardoza, LMFT, is an EMDR practitioner and Consultant specializing in somatic therapy for midlife transitions. She integrates specialized training in nervous system health, somatics, and ego states, with additional training in midlife work from a depth perspective.
Disclaimer
The content on this blog is for educational and informational purposes only. It does not constitute clinical consultation, supervision, or establish a consultative relationship. Reading this blog does not make you a consultee.
This content reflects clinical frameworks and professional perspective but should not replace individualized consultation or supervision for your specific cases. You remain fully responsible for your clinical decisions and treatment planning.
For consultation on specific cases or treatment planning questions, please contact me directly.
Land Acknowledgment
I acknowledge that I live and practice on the traditional and ancestral lands of the Yokut and Mono peoples.
