At Yoga International, we welcome thoughtful scientific dialogue. We’re republishing this informed reflection to offer a clinician’s perspective on the recent critique of Polyvagal Theory and its relevance for therapists and nervous system–informed practitioners. Originally published on drarielleschwartz.substack.com. Re-published with permission.

As a clinical psychologist, I have spent the last 25 years teaching and applying the field of interpersonal neurobiology within psychotherapy. Within this work, I review neuroscientific research on the brain-body connection and explore how this science can benefit us within a psychotherapeutic context—supporting us to navigate stress and heal from depression, anxiety, or post-traumatic stress conditions.

With an interest in clinical application, I am drawn to those theories that help us understand behavior. Perhaps the one that stands out for me the most is the polyvagal theory, developed by Stephen Porges. While there are alternative vagal regulation models as compared to polyvagal theory (PVT) which I will briefly discuss here, I’d love to take this opportunity to share why PVT remains my preferred approach to supporting autonomic integrity in clinical practice.

Polyvagal Theory illuminates the physiological underpinnings of the mind–body relationship and helps us recognize that humans have evolved not only for defense, but for connection. Across all vagal regulation models, it is understood that the vagus nerve, along with the parasympathetic nervous system, supports regulation by inhibiting excessive sympathetic mobilization—reducing heart rate, slowing breath, supporting digestion, and facilitating restoration of bodily systems. Dysregulation of autonomic balance is widely linked to anxiety, depression, post-traumatic stress symptoms, inflammation, and other chronic health conditions.

As discussed in Schwartz (2025), alternative theoretical models also contribute meaningfully to our understanding of vagal regulation.

• The neurovisceral integration model (Thayer & Lane, 2000) proposes that autonomic regulation reflects attentional and regulatory capacities mediated by the prefrontal cortex, influencing emotional processing systems. Vagal tone, often indexed through heart rate variability, is understood as supporting flexible regulation. The parasympathetic system is viewed to be a regulating system for the sympathetic activation. When parasympathetic mechanisms are compromised, this can lead to emotional and physiological dysregulation such as seen with anxiety disorders (Smith et al., 2017).

• The biological behavioral model, developed by Grossman and Taylor (2007), emphasizes synchronization between cardiovascular and respiratory systems and questions aspects of polyvagal evolutionary framing.

• Vagal tank theory proposes three levels of cardiac vagal control analysis, which are resting, reactivity, and recovery suggesting that the physiological “tank” of the vagus nerve can become both depleted and replenished (Hottenrott et al. 2019; Laborde et al., 2017)

• Other models, including resonance frequency breathing (Lehrer & Gevirtz, 2014) and psychophysiological coherence (McCraty & Childre, 2010), and vagal tank theory (Laborde et al., 2018) explore regulatory dynamics through different lenses.

Importantly, these models are not mutually exclusive. They share recognition that autonomic regulation influences psychological functioning. However, these theories of vagal regulation suggest a metaphorical closed circuit in which the primary sources of dysregulation or regulation exist solely within the individual. Where polyvagal theory offers something distinctive is in its emphasis on the relational context of regulation—the understanding that autonomic state is shaped not only internally, but through cues of safety and danger in our social environment. In other words, our vagal tone is intricately connected to our relational, social and cultural exchanges in the world.

When seen through the lens of polyvagal theory, the nervous system can no longer be considered to be a closed circuit of autonomic regulation between heart, breath, and brain; instead, we are an open circuit that dynamically receives and responds to the world around us. We are in relationship to our surrounding environment that is at times a source of regulation through experiences of relational safety or a source of dysregulation when we have relational experiences of betrayal, maltreatment, abuse, or abandonment. In other words, we can draw upon the wise words of 17th century theologian and poet, John Donne, who stated “no man is an island” (Donne, 1987).

Grossman et al. (2026) argue that polyvagal theory is “untenable,” focusing primarily on whether respiratory sinus arrhythmia is a precise measure of central vagal outflow, questioning distinctions between vagal nuclei, and challenging aspects of evolutionary language. These are legitimate scientific discussions. Refinement of measurement and anatomical interpretation is part of how science advances.

It is important to clarify what is being critiqued by Grossman et al. (2026). The central clinical proposition of polyvagal theory—that autonomic state functions as an organizing platform shaping perception, emotion, and relational behavior—was not empirically disproven in the critique. Rather, the debate centers on interpretation of physiological mechanisms and evolutionary framing. When the theory is engaged as it is formally articulated in the peer-reviewed literature, the claim of “untenability” becomes less clear. Portions of the critique appear to address a reconstructed version—at times a misrepresentation—of the theory’s foundational claims rather than its stated principles. Distinguishing between disagreement over mechanisms and refutation of core propositions is essential for an informed evaluation.

As a clinician, I am not indifferent to mechanism. Rather, I recognize that mechanistic refinement and clinical application operate at different but complementary levels. I am engaged in the application of vagal regulation because there is ample research that indicates that stimulation of the vagus nerve has significant benefits on our mental and emotional health (Dufey, et al., 2023; Magnon, et al., 2021; Johnson et al., 2018; Vanderhasselt et al., 2022). Vagus nerve stimulation has shown promising effects on reducing symptoms associated with epilepsy, migraine headaches, rheumatoid arthritis, anxiety, and depression (Goggins, 2022).

In the therapy room, I do not measure RSA; I observe patterns of mobilization, collapse, and connection. I see how physiological state shapes access to cognition, emotion, and relationship. Polyvagal theory provided me with a coherent framework for understanding why cognitive insight alone often fails when a nervous system is in defensive dominance. In such states, higher-order cortical processes are functionally constrained. Simply put, reactions occur before conscious thought and are sometimes do not respond to cognitive interventions. Regulation must precede reflection.

Moreover, I have clinically witnessed the power of co-regulation that occurs across nervous systems. The social engagement system, which includes vagal pathways along with other cranial nerves involved in facial expression, vocalization, and listening, provides a biologically grounded explanation for co-regulation. Polyvagal theory proposes that our neural structures receive passive, nonconscious neuroception of cues of threat as well as cues of safety (Porges, 2022). The vagal circuitry that extends into the face, neck, and throat form a “social engagement system” because of the biological need for social connection that is essential for our survival. In order to bond and attach, we must be able to calm down our primitive defense structures when in a safe environment. This is accomplished by inhibiting the sympathetic nervous system, reducing activation of the HPA axis, and subduing fight-or-flight reactions.

The social engagement system involves a coordination of neural circuitry between the heart, the throat, and the head that allows us to promote feelings of connection and safety through our facial expressions and voice tone. Furthermore, the vagus nerve works in conjunction with cranial nerves V, VII, IX, and XI to integrate sensory and motor feedback from the muscles of the jaw, face, tongue, and neck to coordinate social communications. The vagal circuit also extends into the middle ear muscles, allowing us to listen to and hear the calm and regulating voice tone of another. Through this exchange we are able to sense the loving cadence of a lullaby and the warmth of a smile. This felt sense of safety resonates in the heart and lungs, leading to smooth and rhythmic patterns in heart rate and respiration.

Not only does the social engagement system help us perceive whether another person is calm and safe, but also our face–heart connection will allow us to determine whether another person is a source of threat or danger. It is commonly understood that post-traumatic stress is associated with states of fight and flight reactivity that are driven by the activation of sympathetic nervous system. In such moments, the loss of vagal tone will initiate the activation of our sympathetic fight or flight reaction for the purpose of survival. However, a subset of individuals with a dissociative subtype of post-traumatic stress experience predominant symptoms of depersonalization, derealization, fatigue, malaise, and urge to hide or retreat from social engagement (Lanius, et al., 2022). When we feel trapped and are unable to leave a real or perceived life threatening situation we might move into a freeze or feigned death response (Kozlowska et al., 2015). In this case, the vagus nerve, which is commonly associated with down regulation and immobilization of the body into a relaxation response, initiates another form of immobilization associated with a vaso-vagal syncope, feigned death, or faint response. Recognizing that the vagus nerve can sometimes initiate a “rest and digest” response and other times a vasovagal syncope or faint response presents a paradox of the parasympathetic nervous system. The polyvagal theory is one model to help us better understand this paradox. The so-called “paradox” of parasympathetic involvement in both calming and shutdown states remains a meaningful clinical phenomenon. Polyvagal theory offers one coherent explanatory model for these observations, even as scientific dialogue continues regarding anatomical precision.

For psychotherapists and clients, the polyvagal theory has resonated with our observations of these two types of post-traumatic stress presentations and has provided a profoundly compassionate lens through which we can better understand mental and physical symptoms. The scientific method invites challenge. Questioning hypotheses is not a threat to a theory; it is part of its maturation. At the same time, critiques are strongest when they engage a theory as it is formally described rather than as it is inferred. When readers are informed that some of Grossman’s criticisms rest upon interpretations that differ from the theory’s stated premises, the debate becomes one of scientific interpretation rather than categorical invalidation. If you are just learning of Grossman’s critique of polyvagal theory, it is also good to know the historical context of this debate which began nearly 20 years ago when Grossman & Taylor’s (2007) paper misrepresents the theory in ways that were corrected in Porges (2007). In Porges (2007), he explicitly documents those misrepresentations and addresses them directly. The 2026 Grossman paper largely continues the same line of argumentation. These issues have been addressed repeatedly in subsequent peer-reviewed publications, including Porges’ (2023) “Vagal Paradox” paper as well as in the historical “audit” included in the appendix of his recent rebuttal.

While the critique offered by Grossman et al. brings up important questions about the scientific basis for the claims presented within the polyvagal theory; they have failed to propose an alternative explanation for the paradox of the parasympathetic nervous system or clinical presentations of traumatized clients.

Moreover, the working mechanisms of applied polyvagal theory provides us tangible tools with which we can enhance our wellbeing. I’ll elucidate some of the key principles here:

• Neuroception: We are wired to respond to cues of threat in our environment, and this occurs without conscious awareness. Porges refers to this process as neuroception, which he defines as the innate ability of the nervous system to detect cues of safety, danger, and life threat. While this process can occur automatically, we can also bring conscious awareness to the body to notice the state of activation so that we can better regulate our nervous system.

• Vagus nerve Regulation: Whether through the use of electroceutical devices, conscious breathing, self-applied touch to the ears, cold-water exposure, or yoga we can stimulate the vagus nerve to enhance our wellbeing (Kaniusas, et al., 2019; Pagaduan, et al., 2019). Healthy vagal tone is considered to be a rhythmic alternation between the sympathetic and parasympathetic branches of the autonomic nervous system. When we integrate practices that help repattern the nervous system we can interrupt the downward spiral of stress reactivity to not only reduce symptoms but enhance overall well-being. Through repetition, we consciously rewire our nervous systems to support our resilience and our capacity to be present and effectively respond to stress or environmental challenge.

• Co-regulation: We can offer a calm, soothing, and regulating presence from one person to another through the use of our voice tone, facial expressions, and body language. Louis Cozolino (2014) describes this interpersonal exchange as crossing a “social synapse,” which allows us to sense and respond to another person.

At this time in the world, with active threats of climate change and ongoing sociopolitical stressors along with a global mental health crisis, we need a path forward to help us navigate these challenges with equanimity and resilience. In my professional experience, polyvagal theory continues to provide such a framework. I have personally experienced and witnessed how applied polyvagal theory provides people with tangible tools to enhance our physical, emotional, and spiritual well-being.

When we have access to the internal states that help us feel centered and grounded we are better able to show up in our relationships and in the world at large as a positive presence. I recall an impactful moment sitting with Dr. Porges at an international conference in which he was asked what he has learned as a result of the polyvagal theory. His response was that it taught him about the benevolence of human beings and this gives him hope. For me, being part of the community of scholars applying the polyvagal theory has brought together thousands of people in loving connection. It is for this reason, that I stand behind this body of work.

I encourage readers to carefully examine Grossman et al.’s (2026) article, Porges’ (2026) published response, and the Polyvagal Institute’s overview addressing common critiques. Reviewing these sources together allows for a more informed and balanced evaluation of the arguments and helps distinguish between areas of scientific debate and areas where the theory’s core principles remain intact.

Scientific discourse advances through clarity, careful reading, and thoughtful dialogue. As clinicians, we remain committed to alleviating suffering while remaining open to refinement and continued learning.

Additional Resources:

Grossman et al. (2026) article

Porges’ (2026) response

The Polyvagal Institute public response

References:

• Cozolino, L. (2014). The neuroscience of human relationships: Attachment and the developing social brain (2nd ed.). New York: Norton.

• Donne, J. (1987). Devotions upon emergent occasions. Oxford University Press, USA.

• Dufey, M., et al. (2023) “What the heart brings to therapy: A systematic review on heart rate variability contributions to psychotherapy research.” Revista de Psicopatología y Psicología Clínica 28.3.

• Goggins, E., Mitani, S., & Tanaka, S. (2022). Clinical perspectives on vagus nerve stimulation: Present and future. Clinical Science, 136(9), 695–709.

• Grossman, P., Ackland, G. L., Allen, A. M., Berntson, G. G., Booth, L. C., Burghardt, G. M., ... & Leite, C. AC, Macefield, VG,… & Zucker, I. H.(2026). Why the polyvagal theory is untenable. An international expert evaluation of the polyvagal theory and commentary upon Porges, SW (2025). Polyvagal theory: current status, clinical applications, and future directions. Clin. Neuropsychiatry, 22(3), 169-184.

• 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.

• Hottenrott, L., Ketelhut, S., & Hottenrott, K. (2019). Commentary: vagal tank theory: the three Rs of cardiac vagal control functioning–resting, reactivity, and recovery. Frontiers in Neuroscience, 13, 1300.

• Johnson, R. L., Wilson, C. G. (2018). A review of vagus nerve stimulation as a therapeutic intervention. Journal of inflammation research: 203-213.

• Kaniusas, E., Kampusch, S., Tittgemeyer, M., Panetsos, F., Gines, R. F., Papa, M., . . . & Széles, J. C. (2019). Current directions in the auricular vagus nerve stimulation I–a physiological perspective. Frontiers in Neuroscience, 854.

• Kozlowska, K., Walker, P., McLean, L., & Carrive, P. (2015). Fear and the defense cascade: Clinical implications and management. Harvard Review of Psychiatry. 23(4), 263–287.

• Laborde, S., Mosley, E., & Mertgen, A. (2018). Vagal tank theory: the three rs of cardiac vagal control functioning–resting, reactivity, and recovery. Frontiers in neuroscience, 12, 458.

• Lanius, R. A., Brand, B., Vermetten, E., Frewen, P. A., & Spiegel, D. (2012). The dissociative subtype of posttraumatic stress disorder: Rationale, clinical and neurobiological evidence, and implications. Depression and Anxiety, 29, 701–708.

• Lehrer, P. M., & Gevirtz, R. (2014). Heart rate variability biofeedback: how and why does it work?. Frontiers in psychology, 756.

• Magnon, V., Dutheil, F., & Vallet, G. T. (2021). Benefits from one session of deep and slow breathing on vagal tone and anxiety in young and older adults. Scientific Reports, 11(1), 1–10.

• McCraty, R., & Childre, D. (2010). Coherence: bridging personal, social, and global health. Altern Ther Health Med, 16(4), 10-24.

• Pagaduan, J., Wu, S. S., Kameneva, T., & Lambert, E. (2019). Acute effects of reso­nance frequency breathing on cardiovascular regulation. Physiological reports, 7(22), e14295.

• Porges, S. W. (2022). Polyvagal theory: A science of safety. Frontiers in Integrative Neuroscience, 16, 27.

• Porges, S. W. (2023). The vagal paradox: A polyvagal solution. Comprehensive psychoneuroendocrinology, 16, 100200.

• Schwartz, A. (2025) Neuroception within Trauma Recovery: Sensing the Embodied, Social Self in Grassman, H.; Stupiggia, M.; & Porges, S. W. Somatic-Oriented Therapies. New York, W.W. Norton

• Smith, R., Thayer, J. F., Khalsa, S. S., & Lane, R. D. (2017). The hierarchical basis of neurovisceral integration. Neuroscience & biobehavioral reviews, 75, 274-296.

• Vanderhasselt, M. A., & Ottaviani, C. (2022). Combining top-down and bottom-up interventions targeting the vagus nerve to increase resilience. Neuroscience & Biobehavioral Reviews, 132, 725-729.

*Polyvagal Theory is influential and clinically popular, but some core physiological/evolutionary claims are under active scientific dispute (Grossman et al., 2026; Porges, 2026). We teach it as a framework, not a settled biological map.