Biopsychosocial disequilibrium
Last updated: November 14, 2025
How can we tell when something is wrong with us? In a popular post (6,800 views over four years), Disease, illness, sickness, and disability, I discuss different ideas related to being unwell. I did not explain how someone knows they are unwell. The answer might seem obvious: you develop symptoms, but why and how? There are many health conditions where the reason for feeling unwell is unclear, such as depression, early signs of some cancers, and early signs of most autoimmune disorders. Additionally, some symptoms, like chronic low back pain, are not linked to a clear structural abnormality but are strongly connected to psychosocial factors such as financial stress, divorce, or employment issues. People with these conditions are undoubtedly unwell, but their feelings are not connected to a specific bodily structural or functional problem. How should we analyse and understand this?
Table of Contents
Introduction: equilibrium & disequilibrium
How can you tell when you are unwell? Most people ‘feel unwell’, which usually means experiencing an unusual sensation or feeling. For example, someone might feel hot and sweaty, tired and ‘out of sorts’, or have a weak arm. People also consider whether the feeling has another cause, such as running quickly, which makes one hot and sweaty, or a poor night’s sleep, leading to tiredness.
Similarly, one may feel tense with a tight sensation in the stomach and a dry mouth, and generally feel unwell. Suppose you are waiting for the result of an examination or an interview. In that case, these feelings are often attributed to ‘nerves’ or anxiety, and you do not believe you have any underlying disease. Nevertheless, your experienced feelings are of being unwell.
Generally, we all learn how we feel when everything is well and, conversely, recognise when something is wrong. We then analyse why we do not feel right, as we expect to feel. If we find a reason, we may be reassured and wait for the expected resolution of the feeling. If our analysis indicates a significant cause that requires action, we will take the necessary steps. If our analysis cannot identify a cause, we are likely to conduct further investigation.
I will examine this in more detail. I hypothesise that any person experiencing persistent disequilibrium will notice unusual sensations or feelings, prompting them to identify a suspected cause and attempt to restore balance. This concept applies to all forms of disequilibrium; however, because there are only a limited number of possible feelings, the specific location and cause of the disequilibrium may be unclear. Terms used to describe these feelings include malaise (“Malaise is a general feeling of discomfort, illness, or lack of well-being.”) and malady, and, as experienced by those who feel them, “There is something wrong (with me).”
Homeostasis - behaviour.
I have already discussed homeostasis in my General Theory of Rehabilitation, where I suggest that a health condition disrupts a previous stable state to such an extent that the individual needs assistance to restore a stable balance, mainly focusing on fulfilling their motivational need. The page on homeostasis covers mechanisms.
I am now viewing the issue from the perspective of someone whose equilibrium is disturbed by any change in their life.
Homeostasis refers to the process of keeping variables within a range of acceptable values. These values can be absolute, such as the concentration of glucose in the blood, or relative, such as the proportion of attention allocated to finding food.
The automatic aspects of homeostasis are often subconscious and, for physiological variables such as blood sodium levels, mainly involve biochemical or physiological processes. However, even for physiological variables, behavioural actions can be crucial. For example, dehydration induces thirst, encouraging a person to find and drink water, and persistent hypoglycaemia prompts seeking and consuming food; the individual may not be aware of the underlying reason for their behaviour.
Thus, control over behaviour is a crucial part of all human homeostasis.
Allostasis – adaptive homeostasis.
In 1988, Peter Sterling and Joseph Eyer introduced a new concept, allostasis, to explain the observed link between stressors such as divorce and mortality. The original report was published in a book, in a chapter: Allostasis: a new paradigm to explain arousal pathology. They based their findings on extensive epidemiological and biological evidence.
Peter Sterling has explained the development in Allostasis: A model of predictive regulation, and the title highlights the crucial expansion beyond straightforward feedback. He opens saying, “The premise of the standard regulatory model, ‘homeostasis, is flawed: the goal of regulation is not to preserve constancy of the internal milieu. Rather, it is to continually adjust the milieu to promote survival and reproduction. Regulatory mechanisms need to be efficient, but homeostasis (error-correction by feedback) is inherently inefficient. Thus, although feedbacks are certainly ubiquitous, they could not possibly serve as the primary regulatory mechanism.”
The key point is that living beings must adapt to environmental changes to survive, but adaptation does not always require remaining the same. In other words, simple homeostasis, as originally conceived, keeps variables within a set range, but survival is more likely if the organism adjusts its response to the situation.
For example, bodily temperature is usually maintained around 37°C, but the response to infection is better when the body temperature rises to 38 or 39 °C. This change depends on changing the set point for the feedback mechanism.
Peter Sterling emphasises other differences and some vital implications.
Homeostasis pertains to individual variables, each of which requires its own feedback mechanism. Variables are often interconnected and influence each other. These features can lead to serious, if not deadly, complications if each variable is controlled by a separate mechanism. An allostatic approach acknowledges that more complex control systems exist, which support the stability of the entire system rather than just a single variable.
The nervous system is the primary mechanism that enables the more intricate allostatic control processes.
With evolution, the nervous system also developed the ability to anticipate, allowing it to adjust the set point of a variable for future needs. For example, detecting a potential predator suggests that one might need to fight or flee. Even if one initially observes, preparatory changes in cardiorespiratory parameters occur, including an increase in pulse and breathing rate.
In complex beings like humans, the regulation of many functions is maintained to ensure reactions are efficient and harmonised within the system, enabling anticipation of potential changes before they occur. These allostatic features enhance survival.
Regulation or control?
Douglas Ramsay and Stephen Woods, in their 2014 review, ‘Clarifying the Roles of Homeostasis in Physiological Regulation,’ helpfully distinguish control (within fixed parameters) from regulation (adapting to the immediate or anticipated future state) of a variable. They suggest that numerous regulatory loops are involved within the nervous system and body.
Crucially, using thermoregulation as an example, they suggest that living organisms “represent, not a perfect product of engineering, but a patchwork of odd sets pieced together when and where opportunities arose” [From Jacob, 1977]. In other words, a central single regulatory centre is unlikely. Instead, a network of control mechanisms has evolved to optimise control over a variable.
They conclude, “Based on contemporary views of regulation, and the discussion above, we believe that a balance-point model should be applied to both homeostasis and allostasis.”
They also discuss how allostatic mechanisms can become maladaptive, and one example interests me. Pain stimuli trigger a response that is suppressed by opiates. As tolerance develops and opiate intake increases, the same pain response would be expected. In practice, experiments show sign-reversal as opiate use rises; administering pain may eventually lead to a decrease in certain variables that typically increase. This offers a potential explanation for the reduction in pain observed in people with chronic pain when their opioid doses are decreased.
A further concept indicative of maladaptation by control mechanisms is that of allostatic load. The underlying idea is that bodily changes resulting from changes in the present situation or anticipated changes can become harmful if sustained for too long. Kathryn Seeley and colleagues reviewed this in relation to animals (The application of allostasis and allostatic load in animal species: A scoping review.) and Jenny Guidi and colleagues reviewed the concept in relation to human health (Allostatic Load and Its Impact on Health: A Systematic Review).
The concept of ‘allostatic load’ arising from chronic stress leading to maladaptive reactions is interesting, but peripheral to this post.
Biopsychosocial equilibrium.
Homeostasis and allostasis are feedback control mechanisms applicable to any bodily variable; allostasis can be considered an evolutionary advance on basic homeostasis
The concept that automatic regulation of physiological and other variables extends beyond basic physiology has been recognised for a century. Walter Cannon, in his seminal paper, reviews the early history, and I have provided a summary.
The idea that living organisms utilise feedback mechanisms was initially suggested in 1877, although it may have been proposed earlier. However, in 2020, George Billman stated that homeostasis was still “The Underappreciated and Far Too Often Ignored Central Organising Principle of Physiology”; he also reviews the development of ideas relating to physiology, feedback, and homeostasis. My page on homeostasis provides additional evidence concerning automatic control over psychological and social variables.
Automatic control over physiological variables is entirely accepted. Still, there is also extensive research into control mechanisms within the brain for psychological and social factors, and I provide some evidence in my paper on the General Theory of Rehabilitation, where you will also find a reference to a Central Homeostatic Network; this would be better named the Central Allostatic Network.
Health is increasingly being framed as successful adaptation to a person’s environment, a term that includes not only physical factors but also social and personal factors.
For example, after identifying nine essential features any definition must satisfy, Fabio Leonardi considers health to be “the capability to react to all kinds of environmental events having the desired emotional, cognitive, and behavioral responses and avoiding those undesirable ones.” (See: The Definition of Health: Towards New Perspectives.)
Johannes Bircher gave a similar definition: “Health is a dynamic state of wellbeing characterized by a physical, mental and social potential, which satisfies the demands of a life commensurate with age, culture, and personal responsibility.” In his paper, Towards a dynamic definition of health and disease, he considered treatment, and his conclusion is provocative: “Treatment strategies should always consider three therapeutic routes: improvements of the biologically given and of the personally acquired partial potentials and adaptations of the demands of life.”
He is suggesting that altering external stressors is an integral part of healthcare management. I will enlarge on this later.
Laura Menatti et al (2022) examined health and the environment from both philosophical and public health viewpoints. (see: Health and environment from adaptation to adaptivity: a situated relational account.) Their publication reviews history and highlights that Hippocrates referenced the environment, which has been considered a core aspect of health for a long time.
They highlight that all animals react to environmental change, and emphasise that the crucial concept is adaptivity, not adaptation. Adaptivity is “the capability of a system, such as an organism, to remain viable in its environment by regulating itself, and it is usually related to physiology and behaviour.”
Could being healthy be equated to achieving and sustaining a state of biopsychosocial equilibrium?
This is one possible conclusion that can be drawn from my discussion so far. The person will have allostatic mechanisms aimed at maintaining a stable, balanced set of parameters, which include, but are not limited to, organ and bodily structures and functions, as well as the person’s interactions with their physical and social environment, and their individual motivating factors.
Biopsychosocial disequilibrium.
Supposing my hypothesis is correct, one would expect the person to have a system for attracting attention to disequilibrium and, likely, a tendency towards future disequilibrium. We already understand that our attention is drawn to physiological disequilibrium.
Given that social status and interaction are at least as important to humans, one would expect the evolution of a mechanism that enforces attention to psychosocial instability. A mechanism already exists for biological (physiological) factors, and evolution would probably adapt and utilise an existing system.
This analysis leads to one possible interpretation of many disorders that are not definitely due to any identified pathology:
- A person whose psychosocial balance is unstable will experience some symptoms, drawing attention to the disequilibrium
- These symptoms will be related to or derived from those associated with physiological instability
- The symptoms are also likely to be influenced by the individual’s previous or existing symptomatology.
The person experiencing the symptoms will be unwell, not in a healthy state.
The main challenge is to interpret the presenting symptoms accurately. One might correctly conclude they have a malady; they are in a state of biopsychosocial imbalance and are no longer adapted to their circumstance.
Most people initially attribute symptoms to a traditional organ-based disease, mainly because the symptoms are possibly secondary to organ malfunction. Most healthcare professions share this assumption.
The vital cognitive and attitudinal skills needed by all parties (patient, family, friends, and professionals) are to understand that many factors will impact wellness, including non-physical factors even if an organ pathology is present, and that few illnesses (the person’s experience) present with symptoms that only arise from the pathology.
Therefore, both healthcare professionals and the patient must consider all factors that might contribute to the feeling of unwellness, and should rarely, if ever, accept a single, isolated cause.
Clinical implications of biopsychosocial disequilibrium
This analysis has implications for all healthcare professionals and policymakers.
People seek healthcare professionals for an analysis (diagnosis) of their symptoms and to address feelings of unwellness. Therefore, all clinicians must remain vigilant to biological, psychological, environmental, and social factors that could be a primary or significant contributing cause of unwellness. They should not assume that any single disease or issue is the main or only cause without considering other common factors.
Therefore, all clinicians must be thoroughly familiar with the holistic biopsychosocial model of illness and the common psychological and social factors that contribute to or worsen biopsychosocial imbalance.
Conversely, patients must be informed that not all symptoms are caused by physical illness and that considering psychological or social factors could help improve their health more than focusing solely on any underlying disease. This approach does not deny their illness or symptoms.
Managing organisations, service managers, and policymakers must all recognise that a clinical service should adopt a holistic approach to all patients when making a diagnosis and must not then overlook issues that are likely to cause or worsen the presenting symptoms. The service may not be responsible for providing specialised healthcare, but it is entirely responsible for making an accurate initial diagnosis and, if appropriate, transferring clinical care to another specialist service.
These and other matters are explicitly discussed by Johannes Bircher (see above). The consequences he lists are:
- Deciding if someone is healthy is simplified, though strict criteria are lacking
- The healthcare professional and the patient share responsibility, and both can contribute to improving health
- In every case, whatever the diagnosis, the patient and professional must discuss:
- Increasing any biological potential functions
- Increasing personal potential abilities
- Altering the demands of life
- Health funding should consider
- a person’s responsibility, the moral hazard of their elective, chosen lifestyle and activities
- the limits on responsibility for lifestyle and other changes
- better public health measures, an issue emphasised by Laura Menatti et al (2022)
Conclusion
The idea of biopsychosocial equilibrium, which I introduced in the General Theory of Rehabilitation and expanded upon in a post on Malady, could assist in rethinking certain clinical and policy challenges in healthcare. These are not novel concepts, though I may have broadened their scope. They are particularly relevant to rehabilitation because Rehabilitation Thinking is a skill well-suited for tackling these challenges. Additionally, the idea of biopsychosocial disequilibrium will be applicable in other specialised biopsychosocial healthcare fields such as General Practice (Family Medicine) or geriatrics.