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Wednesday, 12 January 2011 19:52


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Workload and Brain Function

Knowledge about human needs, abilities and constraints provides guidelines for shaping psychosocial work conditions so as to reduce stress and improve occupational health (Frankenhaeuser 1989). Brain research and behavioural research have identified the conditions under which people perform well and the conditions under which performance deteriorates. When the total inflow of impressions from the outside world falls below a critical level and work demands are too low, people tend to become inattentive and bored and to lose their initiative. Under conditions of excessive stimulus flow and too high demands, people lose their ability to integrate messages, thought processes become fragmented and judgement is impaired. This inverted U-relationship between workload and brain function is a fundamental biological principle with wide applications in working life. Stated in terms of efficiency at different workloads, it means that the optimal level of mental functioning is located at the midpoint of a scale ranging from very low to very high work demands. Within this middle zone the degree of challenge is “just right”, and the human brain functions efficiently. The location of the optimal zone varies among different people, but the crucial point is that large groups spend their lives outside the optimal zone that would provide opportunities for them to develop their full potential. Their abilities are constantly either underutilized or overtaxed.

A distinction should be made between quantitative overload, which means too much work within a given time period, and qualitative underload, which means that tasks are too repetitive, lacking variety and challenge (Levi, Frankenhaeuser and Gardell 1986).

Research has identified criteria for “healthy work” (Frankenhaeuser and Johansson 1986; Karasek and Theorell 1990). These criteria emphasize that workers should be given the opportunity to: (a) influence and control their work; (b) understand their contribution in a wider context; (c) experience a sense of togetherness and belonging at their place of work; and (d) develop their own abilities and vocational skill by continuous learning.

Monitoring Bodily Responses at Work

People are challenged by different work demands whose nature and strength are appraised via the brain. The appraisal process involves a weighing, as it were, of the severity of the demands against one’s own coping abilities. Any situation which is perceived as a threat or challenge requiring compensatory effort is accompanied by the transmission of signals from the brain to the adrenal medulla, which responds with an output of the catecholamines epinephrine and norepinephrine. These stress hormones make us mentally alert and physically fit. In the event that the situation induces feelings of uncertainty and helplessness, the brain messages also travel to the adrenal cortex, which secretes cortisol, a hormone which plays an important part in the body’s immune defence (Frankenhaeuser 1986).

With the development of biochemical techniques that permit the determination of exceedingly small amounts of hormones in blood, urine and saliva, stress hormones have come to play an increasingly important role in research on working life. In the short term, a rise in stress hormones is often beneficial and seldom a threat to health. But in the longer term, the picture may include damaging effects (Henry and Stephens 1977; Steptoe 1981). Frequent or long-lasting elevations of stress-hormone levels in the course of daily life may result in structural changes in the blood vessels which, in turn, may lead to cardiovascular disease. In other words, consistently high levels of stress hormones should be regarded as warning signals, telling us that the person may be under excessive pressure.

Biomedical recording techniques permit the monitoring of bodily responses at the workplace without interfering with the worker’s activities. Using such ambulatory-monitoring techniques, one can find out what makes the blood pressure rise, the heart beat faster, the muscles tense up. These are important pieces of information which, together with stress-hormone assays, have helped in identifying both aversive and protective factors related to job content and work organization. Thus, when searching the work environment for harmful and protective factors, one can use the people themselves as “measuring rods”. This is one way in which the study of human stress and coping may contribute to intervention and prevention at the workplace (Frankenhaeuser et al. 1989; Frankenhaeuser 1991).

Personal Control as a “Buffer”

Data from both epidemiological and experimental studies support the notion that personal control and decision latitude are important “buffering” factors which help people to simultaneously work hard, enjoy their jobs and remain healthy (Karasek and Theorell 1990). The chance of exercising control may “buffer” stress in two ways: first, by increasing job satisfaction, thus reducing bodily stress responses, and secondly, by helping people develop an active, participatory work role. A job that allows the worker to use his or her skills to the full will increase self-esteem. Such jobs, while demanding and taxing, may help to develop competencies that aid in coping with heavy workloads.

The pattern of stress hormones varies with the interplay of positive versus negative emotional responses evoked by the situation. When demands are experienced as a positive and manageable challenge, the adrenaline output is typically high, whereas the cortisol-producing system is put to rest. When negative feelings and uncertainty dominate, both cortisol and adrenaline increase. This would imply that the total load on the body, the “cost of achievement”, will be lower during demanding, enjoyable work than during less demanding but tedious work, and it would seem that the fact that cortisol tends to be low in controllable situations could account for the positive health effects of personal control. Such a neuroendocrine mechanism could explain the epidemiological data obtained from national surveys in different countries which show that high job demands and work overload have adverse health consequences mainly when combined with low control over job-related decisions (Frankenhaeuser 1991; Karasek and Theorell 1990; Levi, Frankenhaeuser and Gardell 1986).

Total Workload of Women and Men

In order to assess the relative workloads associated with men’s and women’s different life situations, it is necessary to modify the concept of work so as to include the notion of total workload, that is, the combined load of demands related to paid and unpaid work. This includes all forms of productive activities defined as “all the things that people do that contribute to the goods and services that other people use and value” (Kahn 1991). Thus, a person’s total workload includes regular employment and overtime at work as well as housework, child care, care of elderly and sick relatives and work in voluntary organizations and unions. According to this definition, employed women have a higher workload than men at all ages and all occupational levels (Frankenhaeuser 1993a, 1993b and 1996; Kahn 1991).

The fact that the division of labour between spouses in the home has remained the same, while the employment situation of women has changed radically, has led to a heavy workload for women, with little opportunity for them to relax in the evenings (Frankenhaeuser et al. 1989). Until a better insight has been gained into the causal links between workload, stress and health, it will remain necessary to regard prolonged stress responses, displayed in particular by women at the managerial level, as warning signals of possible long-term health risks (Frankenhaeuser, Lundberg and Chesney 1991).



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