Anxiety & The Nervous System: Understanding Polyvagal Theory and the Window of Tolerance
If you’ve ever felt your heart race before a big event, frozen up when faced with a stressful decision, or experienced a sense of calm after taking a deep breath, you’ve already witnessed your nervous system in action. Anxiety isn’t just “in your head”—it’s a full-body experience driven by the autonomic nervous system (ANS).
Polyvagal Theory, developed by Dr. Stephen Porges, helps us understand how our nervous system responds to stress and safety. It explains why anxiety can show up as fight-or-flight (sympathetic activation), shutdown (dorsal vagal response), or regulated calm (ventral vagal activation). Understanding these states—and how they relate to the window of tolerance—is key to managing anxiety in a way that works with your body, not against it.
Polyvagal Theory: Your Body’s Safety Mechanism
At its core, Polyvagal Theory describes how the Vagus Nerve, a long nerve running from your brainstem to your organs, regulates your response to safety and danger. Your autonomic nervous system shifts between three main states:
Fight or Flight: Sympathetic Activation
This is your high-energy, survival mode—your body’s way of responding to real or perceived threats. When your brain detects danger, adrenaline surges, your heart beats faster, your muscles tense, and you’re ready to fight or flee. This is common when we anticipate something threatening such as speaking in front of an audience. You might notice your hands get clammy, your breath shortens, and you feel restless. Your nervous system is telling you: Get ready!
When it becomes a problem: If you stay stuck in fight-or-flight, you may experience chronic anxiety, panic attacks, irritability, racing thoughts, or difficulty sleeping. Your nervous system is trying to keep you safe—but it’s running on overdrive.
Collapse: Dorsal Vagal Shutdown
When the nervous system perceives that fight or flight isn’t possible, it moves into what’s called feign death mode. This is the body’s emergency brake—an ancient survival response designed to conserve energy and protect you from overwhelm. Have you heard of the term, playing possum? Its pretty much the same for our body. For example, you may need to respond to an urgent email, but instead of typing, you stare blankly at the screen, frozen in indecision. Your body feels heavy, your brain foggy—you just can’t seem to act.
When it becomes a problem: If you frequently default to this state, you may experience numbness, dissociation, depression, fatigue, and avoidance. Your nervous system is shutting down, trying to keep you safe by disconnecting.
Rest & Repair: Ventral Vagal Regulation
This is the golden state of safety, connection, and emotional balance. When you feel calm and engaged, your nervous system is in ventral vagal activation—the state where healing happens. Your breath slows, muscles relax, and your brain can think clearly. For example, you may have noticed that you take a deep breath after a stressful moment and feel your body soften. This is your nervous system returning to homeostasis—a state of balance and regulation.
Why it matters: A well-functioning nervous system moves fluidly between states. It revs up when needed (to meet a challenge), slows down when necessary (to rest), but always returns to a baseline of safety.
The Window of Tolerance: Your Nervous System’s Capacity
Coined by Dr. Dan Siegel, the Window of Tolerance describes the zone where we feel capable, present, and emotionally regulated. Think of it as the sweet spot where you can handle life’s ups and downs without spiraling into anxiety or shutting down. But when stress overwhelms our nervous system, we get pushed outside this window:
🔺 Too much activation = Fight or Flight or Freeze (hyperarousal) → panic, racing thoughts, irritability.
🔻 Too much shutdown = Collapse (hypoarousal) → numbness, dissociation, depression.
The good news? Through Experiential Psychotherapy and Somatic Therapy, you can train your nervous system to stay in its optimal range more often. This means increasing your capacity to handle stress without feeling hijacked by anxiety or overwhelmed by shutdown. And it works, we do this all the time with our clients!
Last Words: Your Nervous System Isn’t Broken—It’s Protecting You
Anxiety is not just a mental health issue—it’s a nervous system response. When we shift from blaming ourselves for our reactions to understanding them, healing becomes possible.
With the right tools, your nervous system can learn that you are safe, even when life feels overwhelming. And that’s where real change begins. To learn more about how different types of therapy can help, visit our Therapy Methods page or reach out to see if we are a good fit for you.
