Defining Trauma Concepts
By now, many of us have heard terms like regulation, dysregulation, “Big T” trauma, C-PTSD—sometimes on social media, instagram posts, TikTok. However, without more context, these terms can end up becoming confusing.
So let’s clarify.
I’ve compiled some definitions and frameworks that I most refer to in my practice with clients who are navigating trauma histories, complex chronic illness, neurodivergence, chronic fatigue, long-COVID, adoptive/foster family systems, and developmental trauma.
Defining Trauma
Definitions of trauma vary, of course.
Because I’m a trained Somatic Experiencing® practitioner, the framework I most often orient to is from Dr. Peter Levine, father of Somatic Experiencing®;
Levine defines trauma not as the event itself, but as the trapped protective mechanisms that remain when there are incomplete survival responses to a perceived threat. I want to emphasize here that the focus is less on the event itself and more how an individual’s nervous system responds to a real (or perceived) threat event.
Dr. Levine writes about this in Waking the Tiger—how animals often shake or tremble after a threat; Levine describes this as part of the process of releasing activation from a completed survival response. However, humans may inhibit (or override) these defensive responses due to cognitive, social, or environmental factors.
When these survival responses remain unresolved in our body, we refer to them as a “chronic” or “stuck.”
Modalities like Somatic Experiencing® are designed to help support the resolution of this particular kind of traumatic stress.
I write more about that here.
Different Types of Trauma
One way to understand different types of trauma is by looking at how they develop. We will do that below, but first I want to define the concept of the “Window of Tolerance” and what some might refer to as “Big T” and “little t” traumas.
Window of Tolerance
Daniel J. Siegel, MD, a contemporary psychiatrist, introduced the Window of Tolerance to mean the range of regulation (or “zone”) in our brain and nervous system where we can live optimally—e.g., process input, respond to life’s demands, integrate information, experiences and stimuli, and even remain centered, present, and regulated.
In other words, the Window is the input (or lack of input) your nervous system can tolerate before shifting to survival/defensive strategies.
On a practical level, when you’re “in your window,” you can connect with others, think clearly, and feel emotions (without getting overwhelmed). The key is that even if you (or a child, for instance) are more active in this state—playing, running, laughing, feeling excitement—you can still remain present and flexible.
However, for some folks—especially those with developmental trauma—a Window of Tolerance may have never adequately developed. And if there is no internalized stable sense of safety—or safe baseline—the system stays activated, as it has no baseline to return to a state of regulation; often, instead, the system may use what are called “defensive accommodations” or coping strategies in an attempt to regulate.
So here we have a nervous system that stays activated (or cycles between activation and shut down) without ever fully returning to regulation. If that continues for decades, we begin to see chronic health issues and compromised functioning. (I refer to this later in the section on allostatic load, and discuss it further in this post here.)
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A Quick Note on “Big T” and “Little T” Traumas:
When people hear the word trauma, they typically think of what has come to be defined as shock trauma or “Big T” trauma.
We often think of “Big T” trauma as potentially life-threatening— serious accidents, violence, war, natural disasters, or medical trauma.
And “little t” trauma as experiences that may not be life-threatening but can still be overwhelming— bullying, loss of an important relationship, or distressing life experiences.
These are not separate categories of trauma; they refer more to the perceived severity or impact of an experience.
Therefore “Big T” and “little t,” matter less than whether the experience overwhelmed the person’s nervous system, exceeding their ability to process and integrate what happened.
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Here we move on to understanding some different types of trauma.
Shock Trauma
Shock trauma often involves a single overwhelming event where a person is unexpectedly thrown out of their Window of Tolerance.
When this happens, the person’s system becomes overwhelmed. A sample sequence of events here may be that the person wasn’t first able to orient to the threat event (and therefore unable to prepare for it). Even if they could, they may have felt helpless, out of control, or as though they had lost their sense of agency in the face of that threat event. Their fight or flight defensive responses may have been insufficient to meet the threat, leaving the nervous system in a chronic state of freeze (or what we sometimes refer to as an “incomplete self-protective response”). Shame often develops alongside this and may also need to be addressed.
If there is a safe baseline or Window of Tolerance to which the person can return after the threat event (an event that was too much, too soon, too fast), then shock trauma can often be resolved through therapies like Somatic Experiencing®.
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Another category of trauma that is important but often overlooked is relational trauma.
Relational Trauma
Where shock trauma is about what happened, relational trauma is often about what didn’t happen—between people and within relationships.
With shock trauma, we often get “too much, too fast, too soon.” And while relational trauma can certainly be that as in cases of abuse, violence, betrayal, or unpredictable threat, more often it develops through patterns of deprivation or “not enough”—not enough support, safety, protection, connection, attunement, and responsiveness.
As a result, it can leave a person feeling erased, betrayed, uncared for, rejected, abandoned, unseen, and unheard. Our nervous system develops and regulates in relationship; they’re an essential nutrient in our development as humans.
Relationships aren’t just about feeling good or feeling loved. They can provide regulation and contribute to our sense of safety in the world. Our livelihood literally depends on them!
Relational trauma can also happen inside many different types of relationships; for example, long-term romantic partnerships, marriages, friendships, with bosses, parents, caregivers, or siblings.
When relational trauma happens early in our development and involves parents or caregivers, it is often referred to as attachment trauma because these early caregiving relationships can disrupt the development of secure attachment.
Attachment trauma occurs within the very relationships our nervous system depends on not only for regulation but a sense of safety. When the people we look to for connection, protection, or attunement are also sources of threat, unpredictability, neglect, or betrayal, the nervous system faces a difficult bind: we cannot simply leave those relationships, especially as children.
The nervous system eventually adapts to these patterns, and they shape how we experience ourselves, other people, and the world.
While Developmental Trauma can be a category of its own, it can also encompass relational trauma because, as I’ve said here, our early relationships help shape the brain and nervous system.
Developmental Trauma
When developmental trauma occurs, that safe baseline or Window of Tolerance may never have been adequately developed.
Conditions for developmental trauma vary, but can include stressed and dysregulated caregivers, adoption (even under the best of circumstances), birth trauma, neglect, interruptions during our time in utero, medical intervention in the first couple of years of life.
I include generational trauma in this category because unresolved trauma can be passed through generations, shaping the relational patterns, attachment, and nervous systems of caregivers and children.
Our nervous systems don’t develop in isolation; they develop through repeated experiences of co-regulation with others.
A safe base provides the conditions needed for healthy nervous system development. The unconscious back and forth that happens between mom and baby — the eye contact, tone of voice, cooing and movement, feeding, nurturing, and physical connection — cultivates the foundation of that infant’s nervous system. There are periods of arousal or activation when the baby has a need or discomfort, and when that need is met by the caregiver, it forms the basis for resilience and regulation. It also begins to create the foundations for ventral regulation and myelination.
(I talk more about developmental trauma here)
Before we look at how trauma affects the brain and nervous system, it helps to understand what happens when the nervous system encounters a threat—and what happens when it is unable to return to a state of safety afterward.
Complex Trauma
Complex trauma is usually understood as combined events and experiences involving shock trauma and/or other forms (sexual, developmental, medical, relational) occurring over time.
Complex trauma can also involve prolonged and repeated experiences that are difficult or impossible to escape, such as childhood neglect, abuse, living with an unavailable or unpredictable caregiver, bullying, or ongoing exposure to threat.
This can be more complex to address than a single shock trauma that occurs in someone who has a stable baseline, supportive relationships, and the ability to return to regulation.
Complex trauma often involves multiple layers of impact, affecting different systems—including attachment and relational systems, as well as physiological systems that influence the body and health.
If we are able to move out of these situations into healthier environments and receive support and healing, the nervous system may have more opportunity to recover and reorganize.
The Brain in Trauma and the Development of PTSD and Complex-PTSD
When trauma happens, our brains (particularly our amygdala) set off survival alarms. This is to help keep us alive! These signals are adaptive and necessary so that the nervous system and stress hormones (like noradrenaline and cortisol) can mobilize the body to help us flee from or fight.
After the threat has passed, this process can often settle relatively quickly. The prefrontal cortex (our executive functioning or “thinking brain”) helps regain perspective, the hippocampus helps organize the memory and communicate that the event is in the past, and the nervous system can return to baseline.
However, with the development of PTSD, that recovery process may be disrupted. The amygdala may remain activated, or the nervous system may struggle to return to a safe baseline—especially in the context of chronic stress, complex trauma, or developmental trauma.
Complex PTSD (C-PTSD) can refer to patterns that develop when the nervous system has been exposed to prolonged or repeated trauma, particularly when there are ongoing stressors and limited opportunities to return to safety and regulation. (I explain this more later when I talk about developmental trauma.)
We might refer to this as “complex PTSD” rather than “complex-PTSD.” The term refers to a pattern of trauma-related symptoms that can develop after prolonged or repeated trauma exposure and may include difficulties with regulation, relationships, self-concept, and a sense of safety.
False or “Faux” Window of Tolerance
While this concept is not the opposite of a real window, nor was it part of Dr. Siegel’s original model, the False Window of Tolerance is an important concept to understand.
One of my teachers, Stephen Terrell, along with his co-author Kathy Kain, in the book Nurturing Resilience, describe the concept of a False (or Faux) Window of Tolerance as a state of disguised dysregulation where a person appears calm, productive, well-regulated, functioning, or controlled on the surface, while the nervous system is actually relying on chronic survival adaptations to maintain that appearance.
It is a kind of defensive mechanism that mimics stability while the nervous system is actually operating outside its true, healthy capacity. Very often, it can lead to burnout and a host of chronic health issues (such as chronic fatigue, sudden collapse or health crises), panic attacks, and depression.
Over time, this requires tremendous energy to sustain and can contribute to burnout, physical health problems, emotional exhaustion, anxiety, depression, or an eventual collapse into dysregulation when the nervous system can no longer maintain the effort.
Allostatic Load
When the body is exposed to prolonged or repeated stress—especially when someone is frequently outside their Window of Tolerance—we begin to see the effects of what is called allostatic load.
In 1993, Bruce S. McEwen (a neuroendocrinologist) and Eliot Stellar (a neuroscientist) coined the term allostatic load in their landmark paper titled "Stress and the Individual: Mechanisms Leading to Disease," published in the Archives of Internal Medicine. Allostatic load describes the cumulative, multi-system "wear and tear" on the body and brain that results from chronic or repeated exposure to stress.
Later, Stephen Porges—father of Polyvagal Theory—referred to allostatic load as the “cost of doing business,” which is apt because every adaptation the body makes in the service of survival carries an energetic and physiological cost. The problem isn't that the body adapts to stress—it's that it has to keep adapting without enough opportunity to recover.
McEwen and Stellar’s work points out that allostatic load may develop through repeated exposure to stress, difficulty adapting to repeated stress, difficulty turning off the stress response after the threat has passed, or a stress response that is insufficient to meet the demands of the situation, which can lead to other systems having to compensate.
A classic example is cortisol. Cortisol is one of the body's primary stress hormones and helps regulate inflammation and mobilize energy during stress. After prolonged or repeated stress, however, the body's cortisol response can become dysregulated. When it no longer responds adequately to the demands of a stressor, other physiological systems—particularly the immune system—must compensate, potentially contributing to persistent or dysregulated inflammation.
Common contributors to allostatic load include chronic psychological stress, unresolved trauma, developmental trauma, caregiving, chronic pain, social isolation, poverty, environmental stressors, poor sleep, inadequate nutrition, inflammation, illness, and substance use.
Over time, chronic activation—and the resulting allostatic load—can impact nearly every system of the body:
Endocrine system: altered cortisol and other stress hormones.
Brain: attention, memory, and emotional regulation
Autonomic nervous system: regulation of arousal and recovery.
Immune system: chronic inflammation or immune dysfunction.
Cardiovascular system: elevated blood pressure and cardiovascular risk.
Metabolism: insulin resistance, altered appetite, and weight changes.
Musculoskeletal system: chronic muscle tension, pain, and fatigue.
This is one reason trauma can have such widespread physical effects without trauma being "all in the mind."
I write more about trauma healing, including how approaches like Somatic Experiencing®, the Safe and Sound Protocol, and other nervous-system-based therapies can support healing and regulation, in my next post.