Polyvagal Theory, Capacity, Embodiment Heidi Oh Polyvagal Theory, Capacity, Embodiment Heidi Oh

Play Is a Nervous System Experience

Explore how play regulates the nervous system through Polyvagal Theory, the window of tolerance, and embodied safety — and why play supports trauma recovery.

In the context of nervous system regulation and trauma healing, play isn’t just a metaphor —

it’s a biological experience. Bodies register play through the autonomic nervous system (ANS), engaging mechanisms that promote safety, social connection, and functional flexibility rather than survival defense. These physiological effects of play are rooted in our neurobiology, particularly through pathways described by Polyvagal Theory and the concept of the window of tolerance.

Play and the Social Engagement System

Central to Polyvagal Theory — a framework developed by neuroscientist Stephen Porges — is the idea that mammals evolved a specialized branch of the vagus nerve that supports safe social interaction and physiological regulation. This is often called the ventral vagal system, part of what some researchers describe as the social engagement system, which links facial expression, vocalization, attention, and autonomic state into a coordinated network geared toward safety and connection.

When the ventral vagal pathways are active, the body is more capable of calm engagement and flexibility. Activities that stimulate face-to-face interaction, gentle movement, rhythm, and shared attention — many hallmarks of play — engage these circuits. These patterns of activation signal safety beneath conscious awareness, lowering defensive states and making regulation more accessible. Unlike cognitive reassurance — “I know I’m safe” — these physiological cues are processed through what Porges calls neuroception: the nervous system’s subconscious evaluation of safety in the environment.

Window of Tolerance and Play

Another neuroscience-informed concept relevant here is the window of tolerance, a model that describes the range of nervous system activation in which a person can function effectively — emotionally, cognitively, socially, and physically. Inside that window, the nervous system can adapt to stressors without becoming overwhelmed or shutting down. Outside it, people may experience hyperarousal (anxiety, panic, defensiveness) or hypoarousal (numbness, dissociation).

Play tends to expand this window by allowing the nervous system to experience manageable shifts in activation in the presence of safety, predictability, and social engagement. Through repeated cycles of activation and recovery — such as laughing, movement, anticipation, pause, and cooperation — the system gains lived experience of returning to regulation. Over time, these experiences can broaden the range of inputs the nervous system can tolerate before tipping into dysregulation.

Play as Bodily Feedback, Not Just Fun

This perspective reframes play from being “just enjoyable” to being a form of physiological input. Through cues like rhythmic movement, facial expression, vocal tone shifts, and reciprocal engagement, play provides the kind of bottom-up sensory feedback that the nervous system uses to calibrate regulation. In other words, play is how the body practices safety. When nervous systems lack safe, patterned experience, regulation becomes harder; when they have repeated patterns of safe activation and recovery, regulation becomes easier.

This helps explain why many people find that structured, serious interventions help their understanding but don’t fully shift how they feel in their bodies. The body learns through experience — not just explanation.

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Polyvagal Theory, Nervous System Regulation, Evidence Based Heidi Oh Polyvagal Theory, Nervous System Regulation, Evidence Based Heidi Oh

Play As a Nervous System Intervention

Explore how play functions as a nervous system intervention in trauma healing, supporting regulation, flexibility, and physiological safety through somatic principles.

Trauma isn’t “just in your head.” It lives in the body

— specifically in how the nervous system organizes defense responses long after a stressor has passed. When the body repeatedly perceives threat without sufficient safety or recovery, protective survival responses (fight, flight, freeze) can remain active even in non-threatening situations. This chronic autonomic activation contributes to anxiety, emotional dysregulation, and a restricted ability to engage socially or experience pleasure. Neurological research shows these patterns are not primarily cognitive; they are rooted in physiological processes that require experience, not just insight, to change.

The Nervous System and Regulation

Central to autonomic regulation is the vagus nerve, a major component of the parasympathetic nervous system that helps slow heart rate and promote recovery after stress. Healthy vagal function — often indexed by heart rate variability (HRV) — is correlated with better emotional and physiological regulation. Research links altered vagal regulation with childhood adversity and chronic stress, suggesting that how the nervous system responds to challenge is a critical component of long-term psychological and physical health.

Stephen Porges’ Polyvagal Theory, while debated in some neuroanatomical details, offers a widely used framework for understanding how autonomic states support social engagement or defensive survival responses. It emphasizes that physiological safety — not just cognitive belief in safety — is necessary for regulation and connection.

Why Play Matters

Play may seem “light,” but it involves dynamic physiological patterns that are exactly what a dysregulated nervous system needs to retrain itself. Play naturally mixes:

  • Activation — through movement and novelty

  • Recovery — through safe end points and social engagement

This cycle allows the autonomic nervous system to experience manageable activation followed by return to calm, thereby strengthening its flexibility. Some practitioners describe this as “exercising the vagal brake,” meaning play helps the nervous system learn how to shift between states of arousal and regulation more fluidly.

While most research on play’s effects comes from developmental studies — showing that free play is linked with improved baseline vagal tone in children — the physiological mechanisms (activation followed by recovery through safe engagement) are not exclusive to childhood. Similar pathways underlie adult nervous system regulation, even if the form of play looks different.

Takeaway

Play is not recreational fluff — it’s a biological experience that contributes to autonomic regulation by repeatedly providing safe activation and recovery. As a nervous system intervention, it supports flexibility, recovery after stress, and stronger social engagement pathways.

  • Free social play in children predicts higher levels of respiratory sinus arrhythmia (a marker of parasympathetic/vagal activity), suggesting play supports autonomic regulation.
    Gleason, T. et al. (2021). Opportunities for free play and young children’s autonomic regulation.
    https://pubmed.ncbi.nlm.nih.gov/34196394/

  • Reviews associations between early adversity and vagal functioning, indicating alterations in autonomic regulation linked with stress exposure.
    Systematic review on childhood adversity and vagal activity.
    https://www.sciencedirect.com/science/article/pii/S0149763422004092

  • Polyvagal Theory describes vagal tone (as indexed by RSA) as a physiological marker of parasympathetic regulation relevant to social engagement and stress response.
    Polyvagal theory (summary).
    https://en.wikipedia.org/wiki/Polyvagal_theory

  • Heart rate variability (HRV), including RSA measures, is widely used in psychophysiological research to index cardiac vagal (parasympathetic) influence and self-regulatory capacity.
    Laborde, S., et al. (2017). Heart Rate Variability and Cardiac Vagal Tone in Psychophysiology.
    https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2017.00213/full

  • In an animal study, natural play behavior elevated HRV (a marker of parasympathetic activation) during and immediately after play, signaling a positive autonomic effect of play behavior in mammals.
    Steinerová, K. (2025). Play behavior increases heart rate variability in pigs.
    https://pmc.ncbi.nlm.nih.gov/articles/PMC11812062/

  • Play supports learning, exploration, social skills, and emotional development, including neural pathway integration — foundational concepts relevant to nervous system processes.
    Learning through play. Wikipedia overview.
    https://en.wikipedia.org/wiki/Learning_through_play

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