Stress, Distress, and Functional Systems

 

Chapter 1. Hans Selye and the Biology of Stress

If the modern literature on trauma and stress has one persistent confusion, it begins with a word that everyone uses and few define carefully enough: stress. In everyday speech, stress means too much pressure, emotional overload, suffering, or exhaustion. In clinical language, it often refers to a broad mixture of external burden, internal tension, physiological activation, subjective distress, and even psychiatric risk. The word has become so elastic that it often names both the cause and the consequence, both the challenge and the collapse. This flexibility is convenient, but it comes at a cost. When one word is used for demand, reaction, strain, and pathology all at once, we lose the ability to think precisely about what is happening in the organism, what is happening in the person, and what kind of help is actually needed.

To recover that precision, we need to return to Hans Selye. This return is not an act of loyalty to a founding figure for its own sake. It is a conceptual necessity. Selye’s original contribution was not merely to popularize the term stress, but to define it in a way that still matters for any serious theory of adaptation. In his work, stress was not identical with emotional suffering, nor with trauma, nor with anxiety, nor with the subjective feeling of being overwhelmed. Stress was the nonspecific response of the organism to any demand placed upon it. That formulation is broader, more neutral, and more biologically disciplined than the way the word is often used today.

Several implications follow immediately from this definition. First, stress is not in itself pathology. An organism under demand must adapt; the very process of adaptation involves mobilization, reallocation of resources, altered priorities, and changes in physiology. Second, stress is not limited to unpleasant events. A challenge, an opportunity, a loss, an infection, a competition, grief, intense work, exhilaration, extreme cold, childbirth, surgery, and fear may all generate stress insofar as they place demands on the organism. Third, what varies is not whether stress exists, but what kind of demand is present, how long it lasts, what resources are available, and whether adaptation remains successful.

Our experimental work in rats with high and low innate resistance to hypoxic hypoxia shows that repeated immobilization stress increases lipid peroxidation and oxidative myocardial damage in all animals, but the injury is most pronounced in low‑resistance males, while high‑resistance rats demonstrate stronger antioxidant defenses. These results underscore that stress systems operate on a background of biological variability: innate resistance and sex shape how repeated stress translates into oxidative burden and organ damage, even when the nominal stressor is the same.

This point is so basic that it is easy to overlook. If stress is the organism’s response to demand, then the absence of stress would not mean perfect health but the absence of life‑relevant challenge. Selye later used the phrase “the salt of life” to capture this paradox: stress, in some form, is inseparable from living systems that must respond, adjust, and survive. The problem, therefore, is not stress as such. The problem is what happens when demands exceed adaptive capacity, when mobilization cannot be resolved, when the organism is driven too long, too hard, or in the wrong direction. That is the road toward distress.

Here, one of Selye’s most useful distinctions becomes essential again: the distinction between eustress and distress. Eustress refers to forms of stress that are mobilizing, growth‑compatible, and compatible with successful adaptation. Distress refers to forms of stress in which the burden becomes damaging, disorganizing, or pathologically costly. The exact border between them is not fixed by the external event alone. It depends on duration, intensity, predictability, control, recovery, biological vulnerability, and the wider context in which the organism must respond. Still, the conceptual difference matters greatly: stress is the broad adaptive response; distress is one of its pathological outcomes.

Modern usage often collapses this distinction. The result is a serious conceptual shortening. If stress already means pathology, then we have no clear word left for adaptive mobilization. We also lose the ability to describe situations in which the organism is highly activated yet functioning appropriately for the conditions. A surgeon during a complicated operation, a parent responding to a child in danger, a rescuer under time pressure, a student preparing intensely for an examination, a citizen in a bomb shelter listening for the all‑clear: all are in states of stress, but not all are in states of pathological breakdown. Some are mobilized toward effective action. Some are exhausted. Some are beginning to cross the threshold into distress. One concept is not enough to describe all these differences if it is used carelessly.

Selye’s second major contribution was to describe a general pattern in how organisms respond to prolonged demands: the general adaptation syndrome. In its classical form, this syndrome includes three phases: alarm, resistance, and exhaustion. Though later research complicated and refined the model, the basic insight remains powerful. Under challenge, the organism first enters an alarm phase: physiological systems mobilize, vigilance increases, and resources are rapidly recruited to meet the demand. If the demand continues, the organism enters a phase of resistance: activation remains elevated, but in a more organized and sustained form; the body and behavior attempt to stabilize adaptation under continuing load. If the burden persists too long, or if resources are insufficient, exhaustion follows: the organism’s adaptive systems become depleted, dysregulated, or increasingly unable to maintain effective response.

The elegance of this model lies in its simplicity. It does not tell us everything about the mind, trauma, learning, or meaning, but it does give us a biologically disciplined starting point. Stress is not a feeling first of all; it is a mode of organismic adaptation. It has phases. It has costs. It has temporal structure. It involves a relationship between demand and response, not merely an event and a complaint. Once that is understood, several later confusions become easier to identify.

The first confusion is between the stressor and the stress response. A stressor is the demanding condition or event. Stress is the organism’s response to it. The stressor may be external or internal, physical or psychological, acute or chronic. A missile strike, a hospital shift, chronic pain, humiliation, a deadline, prolonged uncertainty, infection, displacement, and social rejection are not the same kinds of phenomena, yet each may function as a stressor if it places adaptive demands on the organism. Confusing the stressor with the stress response leads to muddled reasoning. We begin to talk as though “stress” were out there in the world, rather than a process that takes shape in the organism as it tries to meet the world.

The second confusion is between activation and damage. Heightened arousal is not automatically evidence of pathology. In many situations it is the appropriate form of mobilization. A heart rate increase, sharpened attention, narrowed focus, muscular readiness, suppression of irrelevant activity, and temporary sacrifice of comfort for urgent action are all entirely coherent features of adaptive stress. They become part of pathology when they overshoot, persist without recalibration, fail to shut down, or displace other essential functions for too long. If we label every high‑activation state as “bad stress,” we obscure the difference between adaptation and dysregulation.

The third confusion is between short‑term adaptation and long‑term viability. A response may be highly effective in the moment and costly over time. The organism can survive today by borrowing against tomorrow. Increased vigilance, suppression of sleep, emotional numbing, narrowed time horizon, rigid routines, and avoidance of uncertainty may all serve short‑term adaptation under danger. The same patterns, maintained too long, may degrade health, learning, intimacy, restoration, and future planning. Already at the level of biology, Selye’s model implies this tension: resistance can be lifesaving, but it cannot be treated as free.

This temporal aspect is especially important. We are interested not only in whether a system mobilizes, but in what happens to it over time. Stress begins as adaptation. Under some conditions it remains adaptive. Under others it becomes distress. Under still others it becomes chronified, crystallized, and reorganized into broader patterns of life and suffering. To see these later forms clearly, we must begin with the biological neutrality of stress itself.

It is worth pausing here to note what Selye’s framework can and cannot do. It can describe the organism’s generalized adaptive response. It can show that prolonged burden has phases and costs. It can help distinguish demand from breakdown. But it does not by itself explain how a particular person interprets a situation, why one threat becomes central and another does not, how memory shapes anticipation, why certain responses become habitual, or how night‑time phenomena such as insomnia and nightmares are organized in consciousness. For that, we will later need a more articulated systems language. Still, without Selye’s biologically grounded distinction between stress and distress, later theorizing easily loses its anchor.

Indeed, one of the difficulties of contemporary trauma discourse is that it often begins too late in the process. It begins at the level of symptoms, suffering, diagnosis, or dysfunction. Those are clinically important endpoints, but they are not the whole story. Before the diagnosis, there is adaptation. Before the symptom, there is mobilization. Before the pathology, there is a system trying to meet a demand. If we start only with breakdown, we miss the lawful sequence by which a once‑useful response may become too costly, too rigid, or too prolonged.

This is particularly relevant when we move from ordinary burden to trauma‑related conditions. In public and sometimes professional language, trauma is often treated as though it were the opposite of stress, something categorically separate. Yet trauma‑related phenomena can also be placed on a continuum of adaptation under demand, provided we do not flatten their specificity. Hypervigilance, rapid orienting, muscular readiness, sleep fragmentation, emergency prioritization, and suppression of non‑urgent functions are not inexplicable anomalies. They are recognizable stress organizations. The problem emerges when the conditions are prolonged, when recovery is incomplete, when the environment remains unsafe, or when systems built for acute survival become fixed beyond their original context.

At this point, the distinction between acute and chronic stress becomes indispensable. Acute stress is not necessarily mild; it may be intense, frightening, or extreme. What defines it is not its emotional color, but its relative boundedness in time. The organism mobilizes in response to a challenge that, in principle, comes to an end. Chronic stress, by contrast, describes conditions in which demands remain active over longer periods, recur repeatedly, or never fully resolve. Here the question is no longer only whether the organism can mount a response, but whether it can sustain one without collapse, disorganization, or costly reorganization of other life functions.

Selye’s model helps us see why chronic stress is not merely “more” stress. Time changes the meaning of the response. A system designed for urgent mobilization becomes problematic when it must function as a permanent background mode. Hormonal patterns, autonomic tone, sleep architecture, attentional priorities, immune balance, and emotional regulation are all affected when activation becomes enduring rather than episodic. In such cases, the organism is no longer simply reacting to a challenge; it is living in an altered adaptive regime. This shift will later prove essential when we discuss continuous traumatic stress and CCTSD.

Another important feature of Selye’s work is that it was organismic rather than narrowly psychological. Stress is not confined to thought or feeling. It concerns the body as a whole, including endocrine, autonomic, metabolic, and immune processes. This is not a trivial point. Contemporary discussions sometimes swing between two reductions: either stress is treated as “all in the body,” stripped of meaning and subjectivity, or it is treated as “all in the mind,” stripped of physiology and adaptation. Selye’s concept resists both simplifications. It reminds us that the organism responds as an integrated whole, even if later chapters will need to differentiate more finely between bodily activation, predictive models, habits, and conscious experience.

At the same time, Selye’s biological framing must not be misunderstood as crude mechanistic determinism. To say that stress is an organismic response to demand is not to deny interpretation, culture, relationships, or history. It is to insist that whatever meanings and histories are involved, they eventually take shape through adaptive systems that mobilize the body and organize conduct. The same external demand may be metabolized differently depending on memory, expectation, perceived control, social support, bodily condition, and prior learning. Biology does not erase biography; it is one of the ways biography becomes embodied.

This brings us to an especially important transition. If stress is the organism’s response to demand, then stress must be understood not simply as a reaction, but as an organized process. Even in Selye’s early formulation, there is already an implicit systems view: demands arise, the organism mobilizes, resources are allocated, phases unfold, outcomes are compared with what survival requires, and adaptation either holds or fails. Later we will translate this broad biological intuition into the more explicit language of functional systems. There we will speak of reference points, internal models, and action‑learning loops. For now, it is enough to notice that stress is already more than raw arousal. It is organized adaptation in time.

Once this is accepted, several clinical consequences become clearer.

First, not every highly activated person should be understood as disordered. Some are mobilized appropriately for the demands they face. Clinical judgment must therefore ask not only, “How distressed is this person?” but also, “What demand is this system trying to meet, and how realistic is that demand in the present conditions?” This question becomes especially important in contexts of ongoing danger, where what appears pathological from a peacetime standpoint may remain partly adaptive.

Second, the goal of care cannot simply be to suppress activation. If activation is serving an adaptive function, blunt reduction may be unrealistic, mistimed, or even experienced by the organism as dangerous. The more relevant task is to distinguish adaptive mobilization from maladaptive fixation, and to support transitions from necessary stress toward tolerable, flexible, and recoverable forms of organization.

Third, suffering often increases when adaptive systems are misrecognized. A person living in prolonged threat may already be paying the cost of constant mobilization. If that mobilization is then interpreted only as weakness, irrationality, or personal failure, a second layer of burden is added: shame, confusion, and loss of trust in one’s own responses. One reason precise language matters is that it can protect people from being pathologized for surviving in conditions that are in fact pathogenic.

Fourth, any serious theory of trauma must retain a place for biology without reducing trauma to biology. Trauma does not float free from organismic adaptation. It enters sleep, muscle tone, endocrine response, arousal thresholds, attention, and energy allocation. But neither can it be fully explained by endocrine language alone. That is why this chapter comes first, but not last. Selye gives us the biological ground. Later chapters will extend that ground into functional systems, continuous trauma, habits, insomnia, and nightmares.

It is also useful, before closing this chapter, to make one more terminological clarification that will guide the rest of the book:

• A stressor is the demand placed on the organism.
• Stress is the organism’s nonspecific adaptive response to that demand.
• Eustress is stress functioning in a growth‑compatible, mobilizing, or successfully adaptive mode.
• Distress is stress functioning in an overwhelming, damaging, or disorganizing mode.
• A stress system, in the language of this book, is the broader organized architecture through which adaptation unfolds across body, behavior, anticipation, and time.
• A distress system is a stress system that has become pathologically narrowing, self‑reinforcing, or chronically costly.

This vocabulary does not solve every problem, but it prevents an important one. It keeps us from treating stress and distress as synonyms. That distinction, once lost, makes it difficult to understand how people can be under tremendous demand without yet being pathologically broken, and how the same adaptive systems can later become the basis of suffering.

Selye’s importance, then, is not that he gave us a complete theory of human suffering. He did not. His importance is that he gave us a disciplined starting point: living systems respond to demand; this response is lawful; it has phases; it can support life or wear it down; and pathology emerges not from “stress” in general, but from the fate of adaptation under particular conditions of time, intensity, and recovery. For the purposes of this book, that starting point is invaluable.

We will carry three of Selye’s lessons forward. The first is that adaptation comes before pathology. The second is that time changes the meaning of mobilization. The third is that stress must be distinguished from distress if we want to understand what is happening in war, chronic threat, trauma, sleep disturbance, and habit formation without conceptual confusion.

You can learn more by reading our e-book 

Mykola Iabluchanskyi together with Andriy Yabluchanskiy