Time, & biopsychosocial theory

This page explores the biopsychosocial theory of illness from the perspective of time. This exploration leads to specific conclusions about the rehabilitation process for an individual patient and the design and provision of rehabilitation services. It also helps in understanding problems within existing healthcare services.

The relevance of time in healthcare and the design of services receives little attention. Only in the hyper-acute services, such as response to trauma and acute ischaemic events, does time receive attention. The rate of change over time in different systems within the model and diverse healthcare systems may help analyse problems with current services. It particularly may help in designing effective rehabilitation services.

Clinical aspects

This section will analyse how the seven basic systems set out in the biopsychosocial theory of illness are influenced by time. The remaining system, the temporal context, is excluded.

My first hypothesis is that the rate of change varies between the seven different systems. In the first part, I will consider each system and how the differences in the rate of change affect the presentation and management. The evidence provided will, I hope, convince you that the hypothesis is reasonable. In essence, I show that as one moves from disease to social participation, the time scales over which change occurs grow longer, logarithmically. My second hypothesis is that healthcare services need to be designed to match the rate of change seen in different aspects of illness. At present, they are not.

Most of this page concerns hospitals concerned with acute medical and surgical matters. However, there are sections on mental health and palliative care services. The page ends by considering how this analysis might inform the design and provision of rehabilitation services.

Pathology – disease

At the level of pathology, processes and changes occur in short time frames, from almost instant (seconds, such as a subarachnoid haemorrhage or myocardial infarction) to, usually, a few days (e.g. control of a bacterial infection). The patient or their family frequent reach a diagnosis themselves, and the first doctor to see them will achieve a diagnosis in 80% of cases. Final confirmation and achieving more detail may take longer.

The rapid rate of process and change in this system (organs within the body) is reflected in healthcare systems. We have emergency ambulances with paramedics to undertake emergency care, including treatments. There are acute hospital admission processes, intensive care units with 24-hour monitoring etc., set up to respond to the rapid changes.

In the hospital, bed occupancy is monitored 2-3 times a day, discharges are (unfortunately) often arranged at short notice, and only a minority of patients remain in an acute hospital for more than seven days for direct medical care. (see more discussion here)

Many patients need ongoing disease-specific treatment for chronic diseases that cannot be cured (reversed or eliminated) but can be controlled with greater or lesser success. These patients rarely need admission to the hospital for this. Although many are managed well by the general practitioner, there is an increase in disease-modifying treatments that require close expert management. Services for this are not yet well-designed.

The “delayed discharges” label illustrates this emphasis within hospitals on disease-centred short timeframes”. The hospital deems a person delayed discharge when disease-centred processes are complete. This categorisation occurs, whatever need remains for other interventions such as rehabilitation or for care to maintain safety and well-being. (see my post here)


At the level of impaired bodily structure or function, the patient’s experience of unusual (abnormal) bodily functioning, the time scale is generally slower, measured in hours, days or weeks. After any significant disease episode, it takes time for impairments to recover – a period of convalescence while symptoms such as muscle weakness, general fatigue, cognitive slowing etc., return towards normal.

The processes underlying bodily recovery and change are slower than those underlying recovery and change within individual organ tissues. The former are physiological and cross all physical systems which need to adapt. The latter are cellular and biochemical, within a single system, and generally faster.

Some healing processes take time, such as fractures, skin damage, or brain infarction, even at the organ level. The adaptation within the body to irreversible damage usually takes longer. This longer time will impact the recovery of activities, although sometimes this impact can be reduced. For example, an external fixator can lessen the effect of a tibial fracture upon walking.

Actions to reduce impairments also take time to have an effect. Drugs for many neurological impairments such as Parkinsonian symptoms, spasticity, and neuropathic pain may take several weeks to act and often need to be titrated to an effective dose. Treatments to increase muscle strength, reduce lymphedema, or extend contracted joints will all take weeks.

Symptoms, signs and body function are also often the primary measure by which patients and their doctors judge recovery. Sometimes the expected rate of recovery from impairment differs from the actual rate. This discrepancy between expectation and actuality may cause someone to think that they have some other problem if their expectation is for a faster than possible return to the previous function. Alternatively, they may interpret continuing impairment as requiring further rest and restriction, which may slow down improvement.

These timescales are inconsistent with hospital systems focused on disease. The timescales are also challenging to fit in with (UK) booked outpatient clinics, often booked months ahead. Yet, without appropriate monitoring, incorrect expectations may arise and compromise the patient’s well-being.


At the level of activities and disability, the rate of change is much slower. In the presence of continuing impairment, a person needs to learn new ‘behaviours’ and new ways of doing activities. All learning requires time, and learning a complex skill (or relearning it) takes much longer. Consider how long it takes an infant to learn to walk or talk. Or how long it takes to learn to cook well or operate a complicated machine such as a car. The time scale is measured in weeks to many months, occasionally longer.

Three processes influence change in the performance of activities. The first is the natural change associated with ageing. This natural change is a crucial factor in children, perhaps up to 20-25 years. With no well-demarcated starting age in the older population, there is a decline in resilience and some other phenomena such as endurance. However, this phase can only be recognised after it has started. These facts influence rehabilitation but are not themselves alterable.

The second is a natural reduction in impairment as recovery after acute tissue damage occurs. As basic skills recover, so activities become possible or more straightforward. Much rehabilitation immediately after an acute-onset disability is based on the natural recovery process. It focuses on preventing complications and ensuring recovered skills are recognised and used. Recovery may last many weeks.

The third is relearning (or learning if not previously known) how to perform an activity in the presence of whatever skills are preserved and are missing. Relearning is the bulk of rehabilitation late after an acute onset disability and any congenital or progressive disabling disease. This process may take many months.

The much slower change at the activity level contributes significantly to the phenomenon of ‘delayed discharge’. The disease is cured, but it takes much longer for the disability to reduce and for the person to adapt. Unfortunately, most hospitals consider that their principal, if not the only purpose, is the diagnosis and specific treatment of disease. They do not consider rehabilitation to be within their remit, however much the person might benefit from rehabilitation.

Social participation

At the level of social participation, it takes much longer for matters to change. Friendships may take months to form, social networks evolve over the years, as anyone who moves to a new town knows. Only in certain circumstances, such as institutions (e.g. a school, university or some workplaces), do social networks grow more quickly.

This slow rate of change poses a challenge for rehabilitation. The lack of social contact – loneliness – is a significant problem, but it arises after services have withdrawn, even rehabilitation services.


When someone’s previous social networks are lost due to illness, change in social participation is influenced to a great extent by social context. Changes in social context are also slow. It takes years to alter social attitudes, such as the attitude towards smoking or discrimination. The culture within the person’s previous networks may not change, and if it does, it will usually be slow. Meeting new people, developing relationships and entering new networks takes years.

Changes in physical context are also often slow for an individual patient. Even the provision of a wheelchair can take an inordinate time, primarily because of bureaucracy (social context). Adaptations to buildings inevitably take time. Acceptance of changes in physical context by the patient may also be slow. For example, some people are reluctant to use a wheelchair, hearing aids, or a walking stick.

Last, personal context also changes very slowly, if at all. A proportion of ‘personal context’ is simply part of the person, just as the shape of their face or the length of their arms is how that person is. It is their ‘personality’, although this may alter slowly over time or in response to massive events. For example, a near-death experience may transform someone’s approach to life. More mundanely, personal context can be altered deliberately, for instance, through cognitive-behavioural therapy or education, but these take time.

In summary, most changes in context are also slow, sometimes in decades. The main exception is simple alterations to the physical context that do not involve any bureaucracy or significant funding.

Mental Health

It will have been evident that most of the material written above applied to medical and surgical services, especially but not only acute services. Mental health services are different precisely because there is no identifiable disease to be treated. Most treatments in psychiatry focus on impairments, the symptoms and disturbed body functions (brain functions) associated with the disorder and/or the patient’s activities and/or their social functioning.

Therefore, it is expected that people whose mental illness is so severe that hospital admission is needed will have much longer hospital stays. In those patients whose distress is the primary concern, the need is to control symptoms. The treatment team may control symptoms through pharmacological or non-pharmacological means, but it will take weeks in either case because that is how long it takes to achieve change at the level of impairment.

Many patients will be admitted to a mental health hospital primarily because their behaviour threatens their safety or the safety of others. For example, someone may be so withdrawn that they neglect their well-being or might be a high risk of suicide. Others might threaten other people secondary to mania or paranoia. Whatever the aetiology, changing behaviour is likely to take well over a month because changing behaviour is a slow process.

A significant proportion of people with severe mental health problems have difficulties in social participation. Whether this is secondary to a disorder or causally related to a condition, it will often be necessary to try and improve engagement in social activities and the extent of a person’s social network. As the earlier analysis shows, this also takes a long time.

Last, it is evident that the management of functional disorders is centred on changing beliefs, increasing activities and increasing a person’s ability to manage their symptoms. There is no disease to cure. Although some patients are admitted to the hospital, most are not. In either case, management takes considerable time, as would be predicted from the need to alter impairments and activities and, in some instances, social context.

Therefore the general relationships established between each system and timeframes in the context of illness arising from disease hold entirely true in the fields of mental health and functional illness. The relationships support the initial hypotheses.

Palliative care

Palliative care encompasses both end-of-life care and control of symptoms. The latter is usually, but not only in the context of dying.

The biopsychosocial theory of illness does not give any particular insights into the time course in palliative care. The end-of-life phase of an illness is time-limited, but it is difficult to predict its duration. Indeed, good palliative care medical care may well lead both to a better quality of life and a longer life, such that specific end-of-life care is no longer appropriate or needed. In the care home I work in, several people admitted for end-of-life care have survived years, with one returning home and another re-engaged in social activities,

Concerning the explicitly palliative aspects of palliative care services, it is often intractable pain that leads to the involvement of the service. The service is likely to be needed indefinitely because the pain is often associated with progressive disease.

In other words, palliative care is often needed because of progressive disease, usually towards the end of life. Still, the inherent uncertainties in medical prognostication mean that the time course is unknown. Once started, palliative medicine involvement at some level will usually continue until death.

Service implications

This analysis has suggested that change in different systems occurs at different rates, getting slower as one moves from the biological systems (cells and organs) through the body’s functioning and out into goal-directed activities, with aspects of social participation being slowest. In terms of contexts, the rates of change are much more variable in the physical context but are generally slow in the personal context and glacially slow in the social context. What does this mean for service design and delivery?

Historical prelude

History usually explains why something is as it is. Before analysing current services in the light of the analysis above, a look back into history might help.

Before Roman Times, most health problems were covered by a sick person being in touch with a healer. There were no services. The Romans organised their military exceptionally well. They built a surgical service for wounded soldiers and slaves based around valetudinaria, which included a triage centre and acute and longer-term care.

A millennium, hospices (a word derived from Latin hospitum, a place for hospitality) were developed for the ill and weary needing rest or protection. Hospices slowly transformed into hospitals for the more acutely unwell. In the nineteenth century, sanatoria were developed for many people with long-term illnesses such as tuberculosis or mental illness.

As medicine progressed, hospitals became more and more focused on the acute diagnosis and, where available, treatment of disease. Long-term care no longer occurred in hospitals. Huge institutions were built for people with (presumed) mental health problems, and sanatoria primarily for people with TB persisted.

This brief review illustrates that the distinction between immediate diagnostic and treatment organisations and long-term care organisations has existed for two millennia. Only in Roman times, when one organisation (the army) was responsible for both acute and long-term care of their soldiers, was there a close integration between early and late care. It also illustrates that hospitals, now focused on acute care, evolved from institutions once responsible for the long-term sick.

Organisational timescales

The organisational focus is on short-term, high-speed diagnosis and treatment within health. Just under 90% of the NHS budget goes on secondary care in hospitals. In medical hospitals, the lengths of stay are measured in days; in mental health settings, lengths of stay are longer but still measured only in weeks; and in the few identified rehabilitation settings and services that exist, the length of stay or service involvement is measured in weeks to a low number of months.

Secondary care does provide outpatient services. The great majority are single visits for some specific purpose. Some services, such as oncology or rehabilitation (usually just a single therapy), may have a treatment programme. It is relatively rare to continue a long-term commitment to a patient – renal dialysis is one obvious exception.

In summary, the organisation of secondary care health services is predicated on single, defined, relatively short episodes of care. It is also predicated on patients with long-term care needs transferring to community services, such as general practice, other community health services, social services and nursing homes. Moreover, they are predicated on the active involvement of secondary care specialist expertise not being routinely available ‘on demand’ or ‘as needed’ to people in the community.

The problem in services

The problem is probably obvious but will be set out.

Patients present with a problem needing diagnosis and treatment. Diagnosing and treating this problem takes only a few hours or days in general. It fits in well with the timescales of hospitals; they have tailored their timescale to that required to make a diagnosis and give specific treatment. At that point, the person ‘no longer needs medical care’, even if unconscious. Medical care has been redefined as “specialist medical expertise exclusively related to diagnosis and cure or control of a disease”.

Changes in all other levels of a person’s illness are measured in anything from weeks to 12-24 months, or still longer. Many patients need both care to maintain safety and well-being and active rehabilitation. Only the combination will maximise their autonomy in activities and social re-integration, sometimes into new social settings.

The absence of rehabilitation expertise, by which I mean a multi-disciplinary team that works as a team (see page here), exacerbates the problem by failing to identify a person’s prognosis and needs accurately.

The situation is further worsened by the minimal availability of expert rehabilitation services for people outside hospitals – in care homes, community hospitals, and their own homes. Moreover, the existing services are uncoordinated, and all run in different ways with different rules. (see here)

Even medical, disease-focused services have considerable difficulties with the current organisational arrangements. Disease management is increasingly long-term and often requires monitoring and adjusting by people with expertise. So far this need has been met by specialist nurses (not always actually nurses) who work across the boundaries, but this is not necessarily satisfactory for all people.

Funding arrangements have stifled innovation, and not only in the UK. The rapid changes in medical practice associated with Covid-19 demonstrate how severely bureaucracy and commissioning have prevented evolution of services to meet patient needs effectively and efficiently.

The ideal rehabilitation service

For many illnesses, and for most people admitted to hospital, disability is present from the outset

Therefore, management of the disability by an expert rehabilitation service should start from the outset. There are many a priori reasons why this should happen:

  • immobility cause muscle wasting, rapidly, and it takes a long-time to recover muscle bulk;
  • loss of practice at self-care is associated with loss of self-esteem and self-confidence;
  • absence of any planning leads to depression and dependence upon care;
  • and so on.

Early mobilisation is beneficial in the Intensive Care Unit (here), and early specialist rehabilitation assessment of swallowing reduces risk of pneumonia. (here). Very early mobilisation while acutely unwell may carry risk; active mobilisation in the first 24 hours after stroke may be risky. (here)

The implications for the structure of services and the structure of hospitals is clear. All hospital buildings must be designed and built to facilitate patients in retaining or regaining their ability to move and look after themselves even in intensive care. Moreover, all patients need to be seen by a rehabilitation service as soon as possible after admission. Third, the culture of the care environment must facilitate independence despite risks, which are often perceived and not actual.

Any patient who has a disability 48 hours after hospital admission should be seen by a rehabilitation service and have an initial rehabilitation plan, which may be quite short but, in more severe cases, could extend to a Rehabilitation Prescription, shown here. This plan should proceed in parallel with the disease diagnosis and management plan and, naturally, the needs imposed by the disease will have priority. Two benefits arise. Rehabilitation will lower the risk risk of secondary harm and disability arising, and it will increase the speed of recovery.

Patients will only remain in hospital until their care and safety needs can be met outside a hospital setting (see discussion on transferring patients out of a service here). Yet, when people with a persisting disability leave hospital (whether an acute medical hospital or a rehabilitation hospital), they will usually need continuing rehabilitation input to increase further their ability to function at home, in the community, or in work.

Unfortunately at present most people with significant disability at the point of leaving an acute hospital are likely to move through two or three different settings, and often twice as many therapy (or rehabilitation) services. Many patients will have very little active rehabilitation over and above an assessment.

Every move carries risk, but this would be minimised if the same team remained involved with a person as they move. Moves not only carry risk of harm, but they slow down or reverse progress, often for over a week, thus prolonging the episode of care (not to speak of any distress it may cause the person).

Therefore, a single service should be responsible for a patient’s rehabilitation from the time of onset or hospital admission until they are (once more) stable in their preferred long-term accommodation and no longer needing active input from the rehabilitation service. The only reason for changing services should be if the person is moving or needs to move to a different geographic locality.

Finally, even when someone’s situation has stabilised, if they have significant ongoing disability and care needs, they remain at risk of needing rehabilitation input. For example, if they develop an incidental other illness, or a carer changes and the new carer needs training, or if the underlying condition progresses, or if a family member leaves, or if the house needs changing, and so on and on. This they should be able to re-access the same service.

In conclusion, just as a patient expects to be cared for by the same expert medical service over time, wherever they are, so a patient should expect to see the same expert rehabilitation service wherever they are. At present this is not possible because organisationally and contractually the services are chaotic and incoherent. Even the few rehabilitation services available are short-term, whereas disability timescales are measured in months or longer. Medical services are now organising for long-term expert medical responsibility for and involvement with a patient. It is time that rehabilitation services were also organised to allow consistent expert rehabilitation for as long as it is needed.

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