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Understanding the Window of Tolerance and Polyvagal Theory, Part 1

A deeper look into how our nervous system shapes stress, emotions, and connection

When stress feels overwhelming—big emotions, shutdowns, meltdowns, or feeling constantly on edge—it can help to understand what’s happening beneath the surface. Two frameworks commonly used in therapy to explain these experiences are the Window of Tolerance and Polyvagal Theory. These frameworks help us to understand how the nervous system responds to stress, safety, and connection—and how regulation can be supported.

This is part one of a three-part series about these two frameworks. First, let’s discuss the Window of Tolerance.

The Window of Tolerance: Finding the “Just Right” Zone

The Window of Tolerance, a concept introduced by psychiatrist Dr. Dan Siegel, describes the range of emotional and physiological arousal in which a person can function effectively. When someone is within their “window”, they are better able to think clearly, manage emotions, stay present, and engage with others.

When stress pushes someone outside this window, the nervous system may shift into:

  • Hyperarousal (above the window): anxiety, panic, irritability, anger, or difficulty concentrating
  • Hypoarousal (below the window): emotional numbness, shutdown, or withdrawal

This model explains why a child might go from calm to meltdown in seconds, or why a parent might feel “flooded” emotionally during conflict. For children, being outside their window might look like tantrums, defiance, freezing, or withdrawal. For adults, it can show up as overwhelm, snapping at loved ones, avoidance, or feeling emotionally “offline.” Importantly, moving in and out of the window is a normal human experience—especially during periods of stress or change. The goal is not to stay regulated all the time, but to support the ability to return to regulation more gently and consistently.

How to Increase Your Window of Tolerance

The good news is that the Window of Tolerance is not fixed. Over time, and with supportive experiences, people can expand their capacity to stay regulated during stress. Increasing your window does not mean eliminating difficult emotions — it means building more flexibility and resilience in the nervous system so stress feels more manageable.

  1. Build Awareness of Your Arousal States: The first step in expanding the window is noticing when you are approaching the edges of it.

Signs you may be moving toward hyperarousal include: racing thoughts, restlessness, muscle tension, or increased heart rate.

Signs you may be moving toward hyporarousal include: low energy/fatigue, feeling disconnected from self or others, lack of motivation, or difficulty speaking or thinking clearly.

Awareness allows for earlier intervention, which is often more effective than trying to regulate once the nervous system is already overwhelmed.

  1. Practice Regulation Skills That Match Your Nervous System State: Not all regulation looks the same. A key part of expanding the Window of Tolerance is learning to match the strategy to the nervous system state — knowing when the body needs calming (down-regulation) versus gentle activation (up-regulation) (Neff, 2023).

When someone is in a state of hyperarousal, the nervous system is already highly activated. In these moments, regulation focuses on slowing and settling the body.

Helpful down-regulation strategies include:

  • Slow, paced breathing (especially longer exhales)
  • Gentle stretching or grounding movement
  • Sensory calming (soft textures, warm beverages, dim lighting)
  • Orienting to the present moment by noticing sights, sounds, or physical contact with the ground

When someone is in hypoarousal (numb, shut down, fatigued, disconnected), the nervous system needs safe activation, not more stillness.

Helpful up-regulation strategies include:

  • Light physical movement (walking, shaking out the arms, stretching)
  • Temperature shifts (cool water on the face, fresh air)
  • Engaging music, rhythm, or humming
  • Visual engagement or connecting with another person

Rather than forcing a feeling of calm or increased energy, the goal is to gently guide the nervous system back toward the window, one support strategy and moment at a time.

  1. Strengthen Co-Regulation and Safe Relationships: The nervous system develops and heals in connection. Feeling understood, supported, and emotionally safe with others helps widen the window of tolerance over time.

For adults, this might include: supportive friendships or partnerships, therapy or group support, feeling emotionally attuned to by another person.

For children, caregivers play a central role. Calm, responsive adults help children return to regulation and gradually internalize those skills themselves.

  1. Reduce Ongoing Stressors When Possible: Chronic stress narrows the window of tolerance. While not all stressors can be removed, reducing unnecessary demands and building predictability can significantly support regulation. Small, realistic changes can have a meaningful nervous-system impact.

This may look like:

  • More consistent routines
  • Clear expectations and boundaries
  • Adequate sleep, nutrition, and rest
  • Allowing for recovery time after stressful events
  1. Work with a Trauma-Informed Therapist When Needed: For individuals with trauma histories, chronic stress, or neurodivergence, expanding the window of tolerance may require additional guided support. Trauma-informed therapies can help the body relearn safety at a pace that feels manageable.

Expanding the Window of Tolerance is not about pushing through distress or forcing calm. It is about learning to listen to the nervous system, respond with care, and build capacity gradually. Progress is often nonlinear — and that is normal.

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