The origins of stress research

Hans Selye, the Hungarian pioneer of stress research, categorised stress in two ways. One he called eustress, which is the normal beneficial or good stress. The other he called distress, the bad kind (Selye, 1975). Indeed, stress is the result of any kind of change, from something fun and exciting to something potentially harmful or damaging. Enjoying the twists and jolts of a fairground ride produce a similar biological response to having to give a speech to a hundred strangers. People will also perceive these events differently; one might revel in the opportunity to engage in public speaking while another might tremble and panic at the thought of a fairground ride. Of course, few people feel relaxed when they give a speech or presentation, which is why this particular activity is used by researchers to induce anxiety (a procedure known as the Trier Social Stress Test, developed in 1993 at the University of Trier, Germany).

Stress is, therefore, psychological in part yet biological in nature. What I mean by this is that the actual stress response is an evolutionary adaptation designed to make sure humans stay alive. It involves a complex series of biological functions that impact external behaviour. On top of this, our perceptions (or attributions) play a role (Chapter 10), as do our past experiences of similar situations, which is why some people thrive in stressful situations while others flounder. Stress is, therefore, necessary, it makes us feel alert, it excites us and it drives us forwards, leading Selye to suggests that 'complete freedom from stress is death' (Fink, 2016).

The biology of stress

Our bodies actually treat stress in two different ways, dependent upon the nature of the stressor. We can think of these two systems as either the fast system or the slow system; the fast system deals with the immediate stressful situation and returns the body to its default position once it has passed. The slow system, on the other hand, attempts to deal with stressors that might last longer than a few minutes, such as bereavement, moving house or getting married (and yes, these are all considered highly stressful life events).

The fast system: fight or flight

Let us first examine the fast system, often referred to as fight or flight but with the rather less catchy official name of the Sympathetic Adrenomedullary System (or SAM). Say we perceive some kind of threat, perhaps a herd of stampeding bulls. As soon as we witness the threat a signal is sent to a part of a brain called the hypothalamus. The hypothalamus controls the autonomic nervous system, which then activates its sympathetic branch which then, in turn, sends impulses to the adrenal gland (situated just above the kidneys). The adrenal gland then releases a hormone called adrenaline into the bloodstream, targeting messages to different parts of the body. This is the get ready signal, the prepare for action call. Heart rate and respiration increase, providing the body with more oxygen, the liver releases energy into the muscles and the digestive system all but shuts down, causing our mouth to go dry. This is also why many people can't eat when they are in acute stressful situations. Some people have even described an electric shock feeling throughout their body.

This rapid rush of adrenaline allows us to outrun the herd of stampeding bulls and survive until another day. Once the danger has passed, the parasympathetic branch of the autonomic nervous system returns our body to the state it was in prior to the bull stampede.

The fast system, therefore, helps us to cope with acute, or short-term, stressors. The thing is, not all stressors come and go as rapidly as a herd of stampeding bulls.

The slow system

Stressful long-term events such as family disharmony, long-term abuse or a high-pressure job cause stress to last for much longer. This is where the slow system comes in, and it's not all good news. The slow system (the hypothalamic-pituitary adrenal system, or HPA) will activate if the stressor lasts longer than a few minutes. If, for example, the stampeding bulls persisted and we couldn't escape them so easily, our bodies would essentially run out of adrenaline and have to turn to the HPA system. In this instance, the stressor is still processed by the hypothalamus but hormones are sent directly into the bloodstream. The hypothalamus releases corticotropin-releasing hormone (CRH) into the pituitary gland, which in turn releases adrenocorticotropic hormone (ACTH), which then acts upon the adrenal gland, causing it to release a hormone called cortisol. Cortisol enables the body to respond and adapt to changing situations through its regulation of a number of biological functions, including glucose and electrolyte levels, function of the kidneys and liver, blood pressure and wound healing.

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