PHYSICAL STRESSORS	EMOTIONAL STRESSORS
Undergoing surgery	Diagnosis of a chronic disease
Insomnia	Marriage
Loss of eyesight	Travel overseas
Heat stress	Redundancy
Physical trauma	Relationship breakup
Pain	Moving house
Illness	Winning the lottery

Stress prompts the individual into action. The precipitating stressor may be a major life event like a disaster or catastrophe such as a tsunami, or a minor life event such as daily hassles like being late for an appointment because you were caught up in traffic. Additionally the precipitating event can be viewed as negative, harmful and threatening, or challenging and exciting by the individual. Moreover, the same event may be perceived differently by different people as evidenced by the scenario in the following Classroom activity

CLASSROOM ACTIVITY

Imagine you are given a voucher for a parachute jump from an aeroplane as a birthday present.

Would you be excited by the prospect of this adventurous opportunity or terrified at the very thought of doing this?

Pair up with a student whose perception is opposite to yours (negative or positive) and discuss the reason for your view.

Listen to the other person’s explanation to gain an understanding of their view.

Consider why one event might produce different reactions in different people.

Stress as a response, stimulus or process

Stress is a topic of interest not only to health professionals but also to the general public as evidenced by the number of publications on the topic in the pop psychology literature such as in self-help books and health and lifestyle magazines. Furthermore, stress is the most investigated phenomenon in health psychology research with regard to examining the relationship between psychology and disease (Lyons & Chamberlain 2006). Despite this not all researchers use the concept in the same way. Research that investigates the relationship between stress and health fall into three main categories that view stress as one of the following:

• response – the individual’s physical and psychological reaction to the stressor

• stimulus – a stressor in the environment that precipitates a stress reaction

• process – a transaction between the individual and the environment.

Stress as a response

Stress as a response refers to the individual’s physiological and psychological reactions to a perceived threat or stressor, such as the student who discovers that the hard disc on their computer is corrupted and they do not have another copy of an assignment that is due that day. Physical symptoms include dry mouth, palpitations, appetite changes and insomnia, while psychological responses can include anxiety and forgetfulness and, in extreme circumstances, burnout or post-traumatic stress disorder (PTSD). Physiologists in the first half of the 20th century such as Cannon and Selye were the first researchers to describe the stress response and pioneered research in this field.

Walter Cannon (1932) was a physiologist and early stress researcher who first described the fight or flight response – a primitive inborn protective mechanism to defend the organism against harm. The response is a physical reaction by an organism (including humans) to a perception of threat. Cannon observed that when an organism was threatened the sympathetic nervous system and the endocrine system were aroused preparing the organism to respond to the anticipated danger by either reacting aggressively (fight) or by fleeing (flight).

The physiological mechanism of this involves arousal of the sympathetic nervous system that stimulates the adrenal glands to secrete catecholamines (adrenaline and noradrenaline) which then elevate blood pressure, increase the heart rate, divert blood supply from internal organs to muscles and limbs and dilate pupils to enable the organism to take action in the face of a threat (see Fig 10.1). Activation of the endocrine system prompts the secretion of cortisol by the adrenal glands that provides a quick burst of energy, heightened alertness and memory and increases the organism’s pain threshold. Together they enable the organism to confront or withdraw from the threat.

The fight or flight response is adaptive when arousal enables the individual to take action: to either address or escape the threat. However, prolonged arousal, which is unrelenting, or for which adaptation does not occur, is potentially harmful and can lead to long-term health consequences. For example, when caught speeding by a radar and pulled over by a police officer, neither fight nor flight is an adaptive response.

In the landmark Whitehall I and II studies, British civil servants in lower level jobs experienced greater stress due to having less control of their workload than higher level employees (Marmot et al 1997). Further, the final report of the World Health Organization’s (WHO) Commission of Social Determinants of Health states that ‘stress at work is associated with a 50% excess risk of coronary heart disease and there is consistent evidence that high job demand, low control and effort–reward imbalance are risk factors for mental and physical health problems (WHO 2008 p 8).

Research focus

Marmot M, Kogevinas M, Elston M 1987 Social economic status and disease. Annual Review of Public Health Vol 8, pp 111–135

Bosma H, Marmot M, Hemingway H et al 1997 Low job control and risk of coronary heart disease in Whitehall II (prospective cohort) study. British Medical Journal Vol 314, pp 558–565

Whitehall I and II

The first Whitehall study (1967–1976) examined the health of male British civil servants aged between 20 and 64 years. The findings of Whitehall I identified that there was an inverse gradient between the position participants held in the hierarchy of the civil service and mortality. In other words people in senior positions lived longer than those in the lower employment grades. Low-grade workers experienced higher rates of coronary heart disease and three times the mortality rates of workers in the highest grades and this finding was statistically significant. Additionally, the researchers also identified social determinants that were associated with these adverse health outcomes.

Whitehall II followed up on the findings of Whitehall I with a prospective cohort study of over 10,000 men and women, aged 35–55 years, employed in the British civil service between 1985 and 1998 with the purpose of identifying the relationship between occupational and psychosocial factors in the workplace and risk for coronary heart disease for both men and women. The researchers concluded that ‘low control in the work environment is associated with an increased risk of future coronary heart disease among men and women employed in government offices’ (Bosma et al 1997 p 558).

CLASSROOM ACTIVITY

In small groups consider the health profession that your present education is preparing you for such as physiotherapy, paramedic practice, nursing, social work etc.

Identify potential work-related stressors for this professional group and classify them as able to be controlled by the health professional or over which health professionals have low control.

Discuss how events classified as being low control can be made less stressful.

If possible, interview a health professional working in the field and ask them to identify controllable and uncontrollable stressors in their work life.

Compare and discuss the stressors identified by the health professional with those on the list your student group drew up.

GENERAL ADAPTATION SYNDROME (GAS)

Hans Selye (1956) was another pioneer stress researcher who identified the relationship between stress and illness in a model he called the general adaptation syndrome (GAS). The GAS provides a biomedical explanation of the stress response and how it influences health outcomes. The theory identifies a pattern of reaction to a threat or challenge and proposes that stress is the individual’s non-specific response to the specific environmental stressor. Selye defined this as a demand on the body that induces the stress response; that is, the individual is required to adapt (Selye 1956). GAS is non-specific in that the response is the same regardless of stimuli; that is, whether the stressor is physical or emotional or whether it is viewed as positive or negative.

The GAS includes three phases:

• alarm reaction – in which the organism is alerted to a perceived threat

• resistance stage – in which the body attempts to regain equilibrium and adapt to the stressor

• exhaustion stage – occurs when the body’s attempts to resist the stressor are unsuccessful.

When a threat is perceived the body’s reaction is one of alarm and the individual is mobilised to take action. In this phase nervous system arousal and alterations to hormone levels prepare the individual for action. Initially this includes the activation of the autonomic nervous system leading to adrenaline and noradrenaline being secreted by the adrenal medulla. Subsequently, the pituitary gland produces adrenocorticotrophic hormone that stimulates the release of corticosteroids by the adrenal cortex.

With continued exposure to the threat resistance occurs. In this phase hormones remain raised and the immune system aroused as the individual takes further action to cope with the stressor. The exhaustion phase follows if the individual is unsuccessful in adapting to or overcoming the threat. Exhaustion weakens the body’s defences making the individual vulnerable to disease due to depleted physiological resources.

Despite the influence of Seyle’s stress response model on stress research it does not escape criticism. Namely, that it describes a physiological process and overlooks the role of cognitive appraisal as identified by Lazarus and Folkman (1984); second, not all individuals respond in the same physiological way to stress; and third, Selye’s model refers to responses to actual stress whereas an individual can experience the stress response to an anticipated stressor (Taylor 2009 p 148). For example, in agoraphobia the person fears the anxiety they might experience if they leave their ‘safe place’.

In summary, the stress response is an automatic reaction that enables the individual to take action in order to adapt to, or make changes in response to, a perceived or actual threat or stressor. The stress response is most effective for stressors that are of short-term duration and where adaptation is possible. However, should adaptation not be achievable or the stress prolonged the individual is at risk of developing health problems as a consequence.

Stress as a stimulus

Another approach to stress research is to view it as a stimulus that produces a reaction. According to Yerkes and Dodson (1908) stress is the stimulus that prompts action and the amount of stress experienced predicts how well the individual performs The stimulus can be a major life event such as those as identified by Holmes and Rahe in 1967 (see Table 7.4). Alternatively the stimulus may be an accumulation of minor life events or hassles as described by Kanner and colleagues in a study that compared the stress from daily hassles and uplifts with the stress produced by major life events (Kanner et al 1981).

YERKES–DODSON LAW

Yerkes and Dodson (1908) hypothesised that a relationship exists between arousal and performance and that stress is a stimulus that prompts the individual to take action. According to the Yerkes–Dodson law, when stressed (aroused) the individual’s performance increases to a maximum point after which performance reduces. The relationship is represented graphically as an inverted ‘U’ (see Fig 10.2).

Figure 10.2 Yerkes–Dodson law

The model proposes that there is an optimal level of arousal (stress) at which the individual is challenged and thereby performs at their best. With too little arousal the individual is not sufficiently motivated to take action in response to the stimulus and hence performance is minimal. Increasing arousal energises the individual to take the action required to achieve a goal such as study to pass an exam. However, excessive arousal can result in the individual being overloaded and, consequently, performance deteriorates such as the student who is highly anxious about a forthcoming exam and loses concentration or becomes ill.

Major life events

The theory that major life events are a stimulus for stress emerged from the research of Holmes and Rahe who hypothesised that major or frequent changes in one’s life predisposes the individual to illness due to the cumulative effect of the life stressors. This hypothesis was proposed by the researchers after they observed that tuberculosis (TB) infection commonly followed a major crisis or multiple life crises. They subsequently developed a tool to measure the impact of life changes on health and to predict individual vulnerability to illness: the social readjustment rating scale (SRRS) (Holmes & Rahe 1967).

This tool consists of 43 items: 17 are rated as desirable such as going on vacation; 18 are rated as undesirable such as the death of a close friend; and eight are classified as neutral such as ‘major change in responsibilities at work’. Such a change may be the consequence of a promotion that is desirable but it could be the result of a restructure and reduction of staff at your workplace which would be undesirable as there would be fewer people to undertake the workload.

Items in the SRRS are given a weighting that reflects the magnitude of the stressful stimulus (see Table 10.2). For example, the death of a spouse was found to be the most stressful life event and was given a score of 100. A score of 150–299 for the preceding year places the individual at moderate risk for illness, whereas a score of 300 in the preceding six months or more than 500 in the preceding year places the individual at high risk of developing a stress-related illness.

Table 10.2 Scully et al’s updated social readjustment rating scale