Understanding the Window of Tolerance: Making Sense of Stress and Trauma Responses
In clinical work, it’s often surprising how many people have never heard of the Window of Tolerance. Not in a blaming way at all, but more as a reflection of how little this concept is talked about outside of therapy spaces.
At the same time, it’s one of the most helpful frameworks for understanding why we feel and react the way we do under stress.
What Is the Window of Tolerance?
The Window of Tolerance is a concept originally introduced by Dan Siegel. It refers to the range in which our nervous system is able to stay regulated, present, and connected.
When we are within our window, we can:
Think clearly
Stay emotionally grounded
Respond (rather than react)
Tolerate stress and discomfort without becoming overwhelmed
It doesn’t mean we feel calm all the time. It means we can experience emotions, even difficult ones, while still feeling a sense of stability and control, and trust that we can return to baseline.
Everyone’s window looks a little different. Some people naturally have a wider window, while others may have a narrower one, especially if they’ve experienced chronic stress or trauma.
What Impacts the Size of Our Window?
There are many factors that can influence how wide or narrow someone’s window of tolerance is. These include:
Early life experiences and attachment relationships
Exposure to trauma or chronic stress
Current life stressors (work, relationships, health)
Sleep, nutrition, and physical health
Level of social support
Learned coping strategies and emotional awareness
Over time, repeated stress without adequate support can narrow the window, making it easier to become overwhelmed or shut down.
The encouraging piece is that the window is not fixed. With support and practice, it can expand.
Can You Widen Your Window?
Yes, and this is an important part of many therapeutic approaches.
Some of the ways people begin to widen their window of tolerance include:
Building awareness of triggers and early signs of activation
Developing a more supportive relationship with emotions
Practicing grounding and regulation strategies
Increasing body awareness (often through mindfulness or somatic work)
Strengthening safe, supportive relationships
Processing past experiences in a safe and gradual way
Over time, this work can increase confidence in your ability to regulate, which often reduces the fear of becoming overwhelmed in the first place.
What Happens Outside the Window?
When we move outside of our window of tolerance, we enter a state of nervous system dysregulation. This typically shows up in two primary ways: hyperarousal and hypoarousal.
Hyperarousal: The Fight or Flight Response
Above the window is a state called hyperarousal, where the nervous system becomes activated and prepares for action.
This is the classic fight or flight response, associated with increased heart rate, faster breathing, and a surge of energy. Blood flow shifts to support movement, preparing the body to respond quickly to perceived danger.
Emotionally and behaviourally, this can look like:
Anxiety or panic
Irritability or anger
Feeling on edge or hypervigilant
Racing thoughts
Urges to act quickly or impulsively
In some cases, patterns like overworking or substance use as a way to manage the intensity
This response is incredibly adaptive when there is a real threat.
A common example used in therapy is encountering a bear while walking in the forest. In that moment, you want your nervous system to activate quickly, without hesitation, to help you get to safety.
The challenge is that our nervous system, particularly the amygdala, acts like a kind of internal “watchdog.” It scans for danger based on past experiences. Sometimes, it can signal threat even when we are objectively safe.
When that happens, we may feel anxious, reactive, or on edge in situations that don’t actually require that level of response.
Hypoarousal: The Freeze Response
Below the window is hypoarousal, which is essentially the opposite state.
Instead of speeding up, the nervous system slows things down. Heart rate can decrease, energy drops, and the body may move into a kind of protective shutdown. This is often referred to as the freeze response.
People may experience:
Numbness or disconnection
Feeling “checked out” or on autopilot
Low energy or heaviness
Difficulty thinking clearly
Dissociation
From a biological perspective, this response can involve the release of the body’s natural pain-dampening systems, which helps protect us in situations where escape is not possible.
This response is also adaptive. When fight or flight aren’t available or would make things worse, freezing can be the safest option.
This is why many individuals who grew up in unsafe or unpredictable environments learned to rely on this response. It helped them cope at the time, even if it no longer serves them in the present.
The Fawn Response
Another response that has gained more recognition over time is the fawn response. While not part of the original fight or flight model, it has been more recently described in trauma literature, including by Pete Walker.
The fawn response involves prioritizing others’ needs and minimizing your own in order to stay safe. It can look like people-pleasing, over-accommodating, or avoiding conflict at the expense of your own boundaries.
It’s important to understand that this, too, is a stress response. It develops because, at some point, it was safer to appease than to resist.
Like the other responses, it becomes problematic when it is overused in situations where it is no longer necessary.
Why These Responses Can Become Exhausting
These nervous system responses are not the problem in themselves. In fact, they are designed to protect us. The difficulty arises when they are activated too often, or in situations where there is no real threat. Over time, this can be incredibly taxing on the body and mind.
Chronic dysregulation can contribute to:
Ongoing anxiety or burnout
Difficulty concentrating
Sleep disruptions
Emotional reactivity or shutdown
Strain in relationships
It can also leave us feeling depleted, making it harder to respond effectively when we actually need to.
How Our Nervous System Learns
Our nervous system is constantly learning from experience.
A simple analogy is touching a hot stove. You feel pain, pull your hand away, and your system learns quickly to avoid that situation in the future. This is adaptive and protective. The challenge arises when the system begins to generalize too broadly, as if every stove might be hot. In those cases, the window of tolerance can shrink, and the nervous system may remain on high alert or move quickly into shutdown, even when the environment is safe.
Can We Retrain the Nervous System?
To some extent, yes.
We cannot guarantee safety in every future moment, and we can’t prevent all difficult or threatening experiences. What we can do is help the nervous system recognize when we are safe right now.
This often involves small, repeated moments of checking in and orienting to the present. For example, if we return to the forest analogy, imagine having had a previous frightening encounter. It would make sense for your body to feel activated the next time you walk that same path.
Part of the work becomes gently reminding your system: “I am safe in this moment.”
Not convincing it that nothing bad will ever happen again, but helping it distinguish between past danger and present safety. Over time, these repeated experiences of safety can help expand the window and reduce unnecessary activation.
A Balanced Perspective
It’s important to acknowledge that your nervous system is not working against you. It is doing exactly what it was designed to do, based on what it has learned.
The goal is not to eliminate these responses, but to develop a more flexible system, one that can respond when needed and settle when it’s safe to do so.
With awareness, practice, and often the support of therapy, it is possible to feel more grounded, more in control, and less at the mercy of these automatic reactions.
If this resonates, it may be helpful to explore this further with one of our Calgary therapists at Eclipse Psychology. Understanding your own nervous system patterns is often a powerful first step toward meaningful and lasting change.