Returning to Center – Navigating Your Nervous System’s Boundaries
- Brainz Magazine
- Dec 3, 2025
- 6 min read
Written by Aziza Sobh, Registered Psychotherapist
Aziza is a Registered Psychotherapist and Founder of Day by Day Psychotherapy, based in Burlington, Ontario. She is committed to supporting adolescents, adults, and couples in navigating a wide range of challenges. With an academic background in Kinesiology and Psychology, Aziza integrates a holistic approach into her practice.
What really happens after we feel angry, sad, embarrassed, or annoyed? For some people, emotions rise and fall like gentle waves, they take pride in being able to “control” what they feel, rarely sensing that their emotions control them. But what about the moments when the opposite happens? When your heart begins to race, your face flushes, and your body moves before your mind has time to catch up? When you say or do something impulsively, something you later replay with regret? These are the moments of dysregulation, when emotions, thoughts, and behaviours slip out of alignment. And it is here, in the contrast between staying grounded and losing our grip, that the true meaning of self regulation comes into focus.
Window of tolerance
When you hear the phrase “window of tolerance,” what comes to mind? If you immediately think of the optimal zone of arousal, you are right on track. Coined by Dr. Dan Siegel, the window of tolerance helps us understand how the brain and body react to distress, and more importantly, the zone in which we are most capable of thinking clearly, problem-solving, and staying grounded. To get a sense of your own window of tolerance, think back to the last time you felt angry. Did you yell, throw something, or feel physically agitated? Or did you shut down, withdraw, or “turtle” into yourself? These reactions offer clues about whether you were within your optimal zone or pushed outside of it.
The size of your window depends on how much emotional fluctuation you can tolerate, shifts in mood, energy, stress, and life’s everyday demands, while still staying in that optimal, regulated state. The wider the window, the more effectively you can adapt. The narrower it is, the easier it becomes to slip into overwhelm or shutdown.
Within this window, the nervous system feels regulated enough for you to stay grounded, present, and in control of your actions. When you are inside this zone, stress may still be present, but it feels manageable. You can tolerate discomfort, problem solve, and communicate without becoming overwhelmed or shutting down. However, when stressors exceed what your system can handle, you may be pushed outside of this window into hyperarousal, for example, fight or flight responses such as anger, panic, or agitation, or hypoarousal, shutdown, numbness, or withdrawal. The width of a person’s window of tolerance is shaped by factors such as past experiences, trauma history, coping skills, and current stress levels, and it can expand over time with practice, regulation tools, and supportive relationships.
Variables affecting your window of tolerance
When we think about our circle of control, only certain aspects of our functioning fall within it, and our baseline capacity is not one of them. This baseline is shaped largely by genetics and early brain development. Adverse experiences, especially in childhood, can further influence it by narrowing the window of tolerance and heightening the nervous system’s sensitivity to stress. The good news is that while we cannot change our starting point, we can expand our window over time. Through consistent self-regulation strategies, habits, and tools, it is possible to widen this window and remain more regulated, even when faced with adversity.
The state of hyperarousal
Hyperarousal occurs when someone is pushed above their window of tolerance into a heightened state of activation. Emotionally, this often shows up as feeling overwhelmed, anxious, irritable, panicked, or intensely angry. Your reactions feel too big for the situation, and it becomes difficult to think clearly or make grounded decisions.
Physiologically, the body shifts into a fight-or-flight response. Heart rate increases, breathing becomes rapid or shallow, muscles tense, and adrenaline surges through the system. You may feel restless, on edge, shaky, or unable to sit still. In this state, the nervous system is essentially signaling danger, even if the threat is not real or immediate. Because hyperarousal pulls you out of your optimal zone of functioning, it becomes harder to regulate emotions, access logic, or communicate effectively.
The state of hypoarousal
Hypoarousal occurs when someone is pushed below their window of tolerance into a state of underactivation or shutdown. Emotionally, this often presents as numbness, emptiness, disconnection, sadness, or withdrawal. Feelings may seem muted or absent, and it can be difficult to engage with others or respond to the environment.
Physiologically, the body shifts into a freeze or immobilization response. Heart rate may slow, breathing becomes shallow, energy levels drop, and muscles may feel heavy or limp. The nervous system essentially shuts down to protect itself from overwhelm. In this state, cognitive functioning and decision making are impaired, motivation decreases, and it becomes challenging to access emotions or take action, making it difficult to respond adaptively to stressors.
Dissociation often occurs when someone is pushed outside their window of tolerance, typically into hypoarousal or extreme stress, as a protective response to overwhelming emotions or experiences. In this state, a person may feel disconnected from their body, thoughts, or surroundings, emotionally numb, spaced out, or zoned out. Physiologically, the nervous system reduces activation to shield the individual from perceived threat, slowing heart rate, lowering energy, and creating a sense of detachment. While dissociation can serve as a temporary coping mechanism, it also signals that the window of tolerance has been exceeded, making it difficult to process emotions, respond adaptively, or stay present. Understanding dissociation in this context highlights the importance of self-regulation strategies to gently return to the optimal zone of arousal.
How to regulate when you are in hyperarousal
When you start to drift out of your optimal zone and enter hyperarousal, both emotional and physiological changes take place. The sympathetic nervous system is activated, triggering the body’s fight-or-flight response. To return to regulation, calming strategies are needed to help shift from this heightened activation into the parasympathetic nervous system, which fosters feelings of safety, rest, and calm. Building a toolkit of strategies that genuinely work for you is essential. This may include breathing and mindfulness practices, soothing sensory experiences, like tasting something comforting, smelling something pleasant, or listening to calming sounds, or engaging in gentle movement. Because it can be difficult to use these skills once you are already deep in the red zone, learning to recognize the early signs of hyperarousal allows you to intervene sooner, emphasizing prevention rather than damage control.
How to regulate when you are in hypoarousal
When you begin to slip below your optimal zone and enter hypoarousal, noticeable emotional and physiological shifts occur. The nervous system moves into a freeze or shutdown response, leading to numbness, disconnection, low energy, or feeling mentally foggy or distant. To support self-regulation, the goal is to gently re-engage the system and move toward activation. This often involves strategies that stimulate the body and mind, such as sensory input, like holding something textured or sipping something cold, grounding techniques, engaging in light movement, using energizing scents, or connecting with another person. Because it can be difficult to access these strategies when you are already deeply shut down, it is important to identify early cues of hypoarousal so you can intervene sooner. Recognizing these signs allows you to focus on prevention, helping you stay within your window of tolerance rather than working to recover after shutting down.
The takeaway on our nervous system
Understanding the window of tolerance gives us a powerful framework for recognizing our internal states and responding with greater compassion and effectiveness. Whether we find ourselves escalating into hyperarousal or slipping into hypoarousal, these shifts are not signs of weakness, they are natural nervous system responses to stress. By building awareness of our cues and cultivating self-regulation strategies that truly support us, we can gradually expand our capacity to remain grounded, present, and adaptable. Over time, this not only strengthens emotional resilience but also deepens our connection to ourselves and others. Ultimately, learning to navigate our window of tolerance is a practice of returning to balance, honoring our needs, and creating the conditions in which we can thrive.
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Read more from Aziza Sobh
Aziza Sobh, Registered Psychotherapist
Aziza Sobh is a Registered Psychotherapist and the Founder of Day by Day Psychotherapy, a private practice offering counselling services to individuals aged 13 and older and to couples. Holding dual degrees in Kinesiology and Psychology, Aziza is passionate about advancing understanding of the interplay between mental and physical health. With aspirations to pursue a doctorate, her work focuses on raising awareness of the long-term impact of mental health concerns on physical well-being, especially among women.
