The Polyvagal Problem: Why Therapists Need Better Science, Not Better Stories
Polyvagal theory, developed by Stephen Porges (1995, 2007), and its affiliate theories have become incredibly popular in therapy circles. Walk into any trauma conference or scroll through therapy social media, and you'll see people talking about "vagal tone," "neuroception," and the nervous system ladder. Alongside this, Somatic Experiencing (Levine, 1997) has gained traction as a clinical approach that applies body-based methods to help clients resolve trauma responses. Whereas Polyvagal offers a theoretical map of the nervous system, Somatic Experiencing positions itself as a practical way to intervene to create change. Both carry an air of scientific credibility, seem to explain much about how people respond to stress, and have earned enthusiastic followings among therapists.
But here's the problem: popularity doesn't equal validity. And when it comes to vulnerable clients seeking help for trauma, the difference matters more than we might want to admit.
The Polyvagal "Ladder"
Here's the basic narrative that's become popular in therapy circles: Your nervous system operates like a ladder with three rungs. At the top, you've got your "ventral vagal" state (calm, connected, socially engaged). Drop down a rung and you're in sympathetic activation (fight or flight mode). Bottom rung? That's "dorsal vagal" (shutdown, freeze, collapse).
According to this model, we're constantly moving up and down this ladder based on whether our nervous system detects safety or threat through something called "neuroception" (Porges, 2003).
This metaphor has become widely used in clinical work because it's simple and intuitive. But in reality, nervous system responses don't follow a clean, linear sequence. States often blend, overlap, or shift unpredictably. The ladder is helpful as a conceptual tool, but it's not a literal map of how the autonomic nervous system functions and it's definitely not backed by firm scientific or biological evidence (Neuhuber & Berthoud, 2022).
Where the Science Gets Shaky
The more you dig into actual neuroscience research, the more problems you find with polyvagal theory's basic claims. There's broad consensus among neuroscience experts that many of the theory's foundational assumptions are either unproven or contradicted by comparative anatomy and physiology (Grossman & Taylor, 2007; Monteiro et al., 2018; Neuhuber & Berthoud, 2022).
The biggest issue? The theory claims that the dorsal and ventral branches of the vagus nerve evolved at different times and serve different functions (hence the "poly" and "vagal"). The ventral branch supposedly evolved later and is only seen in mammals. However, this isn't supported by current evidence. Studies of lungfish and other non-mammalian species show that these structures actually exist across many vertebrates (Monteiro et al., 2018).
Then there's the measurement problem. Polyvagal theory relies heavily on heart rate variability—specifically respiratory sinus arrhythmia—as a measure of "vagal tone," but research shows this isn't necessarily a reliable indicator of overall vagal function. It's influenced by too many other variables to be treated as a clean window into nervous system regulation (Grossman & Taylor, 2007).
The hierarchical ladder metaphor? Critics argue there's no empirical support for the strict evolutionary progression the theory proposes. Real nervous system responses are messier and far more context-dependent (Neuhuber & Berthoud, 2022).
Why Polyvagal Became So Popular (And Why That's Problematic)
Before we go further, let's acknowledge why polyvagal theory gained such traction. It arrived at a perfect moment in therapy culture:
It provided a bridge. Many therapists were already seeing the value of body-based interventions but lacked a scientific-sounding framework to explain them. Polyvagal theory offered that framework, complete with evolutionary narratives and neurobiological terminology.
It felt empowering. Rather than pathologizing clients, it normalized their responses as "natural" reactions of an ancient nervous system. This was genuinely helpful for many people who'd been told their trauma responses were signs of personal failure.
It simplified complexity. The three-tier model is elegant and teachable. Training programs could build entire curricula around it. Therapists could explain client experiences in ways that felt both scientific and accessible.
But popularity based on utility isn't the same as scientific validity. And when an unproven theory becomes institutionally entrenched—built into training programs, certification requirements, and professional standards—we have a problem.
The Real Stakes: Why This Matters
This isn't just academic hairsplitting. When therapists confidently explain "vagal tone" and "neuroception" to clients, several concerning things happen:
False Authority: Therapists position themselves as having scientific knowledge they don't actually possess. Clients, who are often in vulnerable states, may accept these explanations uncritically and base important life decisions on them.
Delayed Treatment: Clients might spend months or years focused on "regulating their nervous systems" instead of accessing evidence-based treatments for trauma, anxiety, or depression.
Learned Helplessness: The focus on automatic, unconscious "neuroception" can inadvertently teach clients they're at the mercy of their nervous systems rather than capable of developing conscious coping strategies.
Professional Stagnation: The field stops advancing when we mistake appealing narratives for scientific progress. Polyvagal theory has consumed enormous amounts of professional attention and training resources that might have been better spent on approaches with stronger evidence bases.
Ethical Concerns: Professional ethics require therapists to base their interventions on the best available evidence. When we build practices around theories that experts consider scientifically unfounded, we may be violating this fundamental obligation.
What Therapy Looks Like Through This Lens
Despite the shaky science, many therapists report that polyvagal-informed approaches help people. Sessions often focus on tracking internal cues, recognizing patterns of activation or shutdown, and using body-based techniques to increase awareness and regulation.
That might look like:
Naming internal states like "I feel frozen" or "I feel braced."
Using breath, movement, or grounding to shift out of shutdown.
Exploring what safety feels like in the body.
Identifying the kinds of environments or interactions that trigger defensive responses.
This kind of work can be powerful. But here's the key: none of it requires uncritical acceptance of Polyvagal Theory's evolutionary claims. Clients benefit from experiential awareness and practical regulation tools…not from whether Porges's account of mammalian vagal pathways is anatomically correct (Neuhuber & Berthoud, 2022).
The "It Works" Fallacy
Many polyvagal advocates respond to scientific criticism with some version of "but it works in practice." This response reveals a fundamental misunderstanding of how science and practice should relate.
Correlation isn't causation. Just because clients improve during therapy that uses polyvagal concepts doesn't mean those concepts are scientifically accurate. The improvements might come from:
The therapeutic relationship itself
Increased body awareness (which doesn't require polyvagal theory)
Interoceptive exposure—gradual, safe exposure to internal bodily sensations that reduces fear and avoidance
General mindfulness and grounding practices
The normalization of trauma responses (achievable without evolutionary narratives)
Therapist confidence and enthusiasm
Effectiveness doesn't validate theory. Many discredited approaches in psychology's history "worked" for some people. Recovered memory therapy, multiple personality disorder treatment protocols, and various forms of conversion therapy all had practitioners who swore by their effectiveness.
Alternative explanations exist. We can acknowledge that body-based interventions help many trauma survivors without accepting specific—and scientifically problematic—explanations for why they work.
A More Direct Approach
Instead of confidently explaining vagal pathways and evolutionary hierarchies, what if therapists focused on what we can observe and what actually helps?
"When you're stressed, your body responds in predictable ways. Some people get activated (heart racing, muscles tense, ready to act). Others shut down (feel numb, disconnected, like they're watching from outside their body). Let's pay attention to what happens in your body and figure out what helps you feel more regulated."
This framing still validates clients' embodied experiences, integrates breathing and grounding practices, and encourages mindful awareness of stress responses. But it does so without leaning on speculative neuroscience or overstated evolutionary stories.
We can also be more honest about uncertainty: "We're still learning how trauma affects the body and what helps people heal. What we do know is that paying attention to your physical responses and finding ways to feel safer in your body can be really helpful. Let's explore what that looks like for you."
The Institutional Problem
Individual therapists aren't entirely to blame for this situation. Polyvagal theory hasn't just influenced practitioners—it's become embedded in the institutional infrastructure of mental health training:
Training Programs: Entire curricula are built around polyvagal concepts. Students graduate believing they've learned established neuroscience when they've actually learned one person's contested theory.
Certification Bodies: Organizations offer "polyvagal-informed" certifications, lending institutional credibility to scientifically questionable ideas.
Continuing Education: Conference presentations and workshops routinely present polyvagal concepts as settled science rather than speculative theory.
Publishing: Books and articles assume polyvagal validity rather than treating it as one theoretical framework among many.
Professional Organizations: Some therapy organizations have essentially endorsed polyvagal approaches without requiring the kind of scientific scrutiny they would apply to pharmaceutical interventions.
This institutional entrenchment makes it difficult for individual practitioners to question polyvagal concepts without feeling like they're challenging the entire profession.
The Way Forward
This doesn't mean we need to abandon body-based approaches or stop paying attention to autonomic responses. Instead, we need better intellectual humility and scientific rigor:
For Individual Therapists:
Hold polyvagal concepts lightly. Use them as potentially helpful metaphors, not as established facts.
Focus on what's observable and what helps, rather than on theoretical explanations.
Be honest with clients about the speculative nature of these ideas.
Stay curious about alternative frameworks and new research.
Acknowledge when you don't know something rather than defaulting to polyvagal explanations.
For Training Programs:
Teach polyvagal theory as one contested framework among many, not as established neuroscience.
Include scientific criticisms alongside theoretical presentations.
Emphasize clinical observation and evidence-based practices over theoretical allegiance.
Require students to understand the difference between metaphor and mechanism.
For the Profession:
Demand higher standards of evidence for widely adopted theories.
Create space for scientific debate without professional retribution.
Invest research resources in rigorous studies of body-based interventions that don't depend on specific theoretical frameworks.
Develop ethical guidelines for how therapists should present scientific uncertainty to clients.
The Bigger Picture
Polyvagal theory isn't the first psychological framework to get popular before the research caught up, and it won't be the last. Exciting new ideas capture people's imagination, gain traction in the clinical world, and only later face serious scrutiny.
The real issue isn't polyvagal theory itself—it's our field's tendency to embrace appealing narratives before we've done the hard work of scientific validation. We're drawn to theories that seem to explain everything, that give us confidence in our interventions, and that offer hope to our clients. These are understandable impulses, but they can lead us astray when we mistake eloquence for evidence.
The human nervous system is incredibly complex. Trauma affects people in diverse and often unpredictable ways. We're still figuring it out. Maybe that uncertainty makes people uncomfortable, but it's more honest than clinging to elegant-sounding theories that don't hold up to scrutiny.
The Bottom Line
Attention to the nervous system and body-based interventions can be valuable in therapy. But we should be much more cautious about the frameworks we use to explain them.
When therapists speak with certainty about vagal tone and neuroception, it's worth raising an eyebrow. The human nervous system is incredibly complex. We're still figuring it out. Maybe that uncertainty makes people uncomfortable, but it's more honest than clinging to elegant-sounding theories that don't hold up to scrutiny.
If you're a therapist using polyvagal concepts, this definitely doesn't mean you need to throw everything out. Just remember to hold it lightly. Focus on what you can observe, what helps, and what your client finds useful. Let the neuroscience catch up. And be willing to admit when something is a helpful metaphor rather than established fact.
And if you're seeing a therapist who talks a lot about polyvagal theory? Ask questions. A good therapist should be able to explain why they're using certain approaches, acknowledge their limitations, and be honest about what's speculative versus what's well-established. If they can't tolerate that kind of conversation, that tells you something important about how they approach their work.
Good therapy doesn't require pretending we understand the brain better than we actually do. Sometimes the most helpful thing we can offer clients is honest uncertainty paired with genuine curiosity about what might help them heal.
References (APA 7th ed.)
Grossman, P., & Taylor, E. W. (2007). Toward understanding respiratory sinus arrhythmia: Relations to cardiac vagal tone, evolution, and biobehavioral functions. Biological Psychology, 74(2), 263–285. https://doi.org/10.1016/j.biopsycho.2005.11.014
Levine, P. A. (1997). Waking the tiger: Healing trauma. Berkeley, CA: North Atlantic Books.
Monteiro, J. D., da Silva, J. R., Klein, W., Mota, C., Severino, M., & Leite, C. A. (2018). Vagal efferent pathways in the lungfish: Implications for the evolution of autonomic control. The Journal of Comparative Neurology, 526(17), 2844–2860. https://doi.org/10.1002/cne.24521
Neuhuber, W. L., & Berthoud, H. R. (2022). The mammalian vagus nerve: A structural and functional critique of the Polyvagal Theory. Biological Psychology, 169, 108266. https://doi.org/10.1016/j.biopsycho.2022.108266
Porges, S. W. (1995). Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A Polyvagal Theory. Psychophysiology, 32(4), 301–318. https://doi.org/10.1111/j.1469-8986.1995.tb01213.x
Porges, S. W. (2003). The Polyvagal Theory: Phylogenetic contributions to social behavior. Physiology & Behavior, 79(3), 503–513. https://doi.org/10.1016/S0031-9384(03)00156-2
Porges, S. W. (2007). The Polyvagal Perspective. Biological Psychology, 74(2), 116–143. https://doi.org/10.1016/j.biopsycho.2006.06.009
