نقش تجربه در کار شب: درسهایی حاصل از دو مطالعه ارگونومیک

The purpose of this article is to analyze some connections between experience, health and work, especially in the field of night work. As a result of the baby boom, the proportion of elderly workers is steadily increasing, while at the same time many workers are reaching retirement age and being replaced by younger people. And, in the same time, there is an overall gradual increase in shift work and night work. To our knowledge, worker experience has not been extensively studied in this context. This was our focus in studying work activity in two very different situations, in a hospital and in a steel industry. In these two studies we observed that the experienced workers endeavor to plan ahead, especially at night. They do this to limit fatigue and to avoid emergencies and ensure that work is stress-free and as far as possible under control. But experience not only brings workers to plan ahead, it also enables them to do so, thanks to the resources it confers: gaining familiarity with tasks and acquiring the ability to identify critical situations, gaining knowledge about themselves and awareness of situations that cause difficulty; and gaining a better overview of the collective aspects of their work and of ways to share tasks or obtain assistance. They are able to undertake these strategies thanks to specific skills and capacities they have built along their professional career, which notably leads them to find the best trade-off between several goals, possibly contradictory. Such experience is especially valuable at night, when the worker is tired, and when there are fewer supervisors present. This experience can only be gained, however, if the work environment fosters its acquisition and provides an opportunity to make use of it, especially during the night shift and especially with respect to planning tasks ahead of time.

Our purpose of this article is to analyze some connections between experience, health and work, especially in the field of night work. Actually, numerous researches already deal with regulation processes implying age and experience-related effects (Laville et al., 2004), but schedule issues are not often taken into account in their results. Conversely, studies about age-related effects of shift and night work (Costa, 1996, Touitou et al., 1997 and Marquié et al., 1999) do not usually pay attention to the specificity of work activity at such a period; nor do they highlight how experience, in particular experience “in” night work, may allow to build efficient strategies in order to protect one’s health and safety. Yet it is easy to bring out the social focus of research on the merged topics of irregular work schedules (especially night work) and experience. At this point it is important to delve into the implications of two ongoing developments. The first is demographic change (Auer and Fortuny, 2000). As a result of the baby boom – the upturn in the birth rate in the 1950s and 1960s, followed by a decline, the proportion of elderly workers is steadily increasing, while at the same time many workers are reaching retirement age and being replaced by younger people. The second development involves the way in which work schedules are designed: there is an overall gradual increase in shift work and night work. These changes in worker age and working hours predictably have two consequences. One is an increase in night work among aging workers. Such a trend is already observable in France (Bué and Rougerie, 1999). Some of these workers just remain on these schedules because it is an intrinsic component of their job, for example in press companies (Lortie et al., 1979) or customs (Prunier-Poulmaire et al., 1998). Some others “discover” night work in the second part of their career, mainly among non-skilled workers for which this type of constraint appears presently as the only “solution” to get a job (Gadbois, 2002). The other consequence is that in more and more frequent situations, workers of different generations work side by side, whatever the hour, and in particular at night. These encounters might help skills transmission and learning. It might on the contrary increase possible conflicts between generations, in particular when the most harmful tasks are being allocated to young employees; it might also tend to push away the elderly if they are seen as less hardy or less efficient in shift or night work. To shed light on this topic, a vast body of knowledge is available – notably findings from ergonomic research. We are, for example, able to assess the effects of age on night-shift tolerance (Barbini et al., 2007), with the prevalence of sleep disturbances, accumulated fatigue and sometimes health issues increasing with age (Brugere et al., 1997). But to our knowledge, worker experience has been less extensively studied in this context. This was our focus in studying work activity in two very different situations, which we shall go back over in this article. We shall first present the general framework of this reflection. Then we shall describe separately some methods and results of each study, then get on to a common discussion.

We are comparing two studies here that are essentially quite different. Work is, for example, in many ways more physically taxing in a steel mill than in a hospital (where nevertheless physical stress is not negligible). The uncertainty factors – and we saw the major role that they play, especially at night – are not the same in the two cases: the steel manufacturing process is to some extent unpredictable, but obviously the condition of hospital patients and the care they require are even more difficult to reliably anticipate and plan for. Last but not least, work in the factory is fast-paced and subject to tight and very precise scheduling (a coil comes off the rolling-mill every three minutes on average, but sometimes at much faster intervals if the coil is short), whereas most hospital tasks – except for emergency situations – can be postponed for several minutes without serious consequences. Nevertheless a number of essential findings proved to be the same in both studies. We see that the experienced workers endeavor to plan ahead, especially at night. They do this with two objectives in mind – to limit fatigue (especially in the middle of the night, when it peaks) and to avoid emergencies and ensure that work is stress-free and as far as possible under control. Experience not only causes workers to plan ahead, it also enables them to do so, thanks to the resources it confers. With experience, workers gain familiarity with tasks and acquire the ability to identify critical situations that are likely to occur; they gain knowledge about themselves and awareness of situations that cause difficulty and should therefore be avoided; they gain a better overview of the collective aspects of their work and of ways to share tasks or obtain assistance. They are able to undertake these strategies thanks to specific skills and capacities they have built along their professional career, which notably leads them to find the best trade-off between several goals, possibly contradictory: do well and do fast; (at hospital) converse with the previous team and start visits in the rooms without waiting; (at the rolling-mill) watch closely the coils and exchange information with the mill chief. With this aim in mind they may elaborate new goals, or at least new balances between goals, in order to overcome tensions and discrepancies. Therefore they will adjust their way of doing, broaden their own field of interventions (at the rolling-mill: “negotiating” with the mill technician), and even break or at least reinterpret some rules (at the hospital: move the moment of a treatment, so that the patient will sleep a little more). Such experience is especially valuable at night, when the worker is tired, and when there are fewer supervisors present. This experience can only be gained, however, if the work environment (equipment, access to relevant information, composition and stability of teams, opportunities to discuss work with others, training programs, etc.) fosters its acquisition and provides an opportunity to make use of it, especially during the night shift and especially with respect to planning tasks ahead of time. These findings generate tangible ideas for ergonomic intervention, which we shall not go into in this article. As far as orientations for further research are concerned, we think it would be interesting and beneficial to study shift work, more specifically night work, and the issues they involve in terms of health and performance at work, in the context of two other time dimensions. One dimension is more immediate: time constraints at a particular moment, emergencies and forward planning. The other is more long-term: career development and the acquisition of experience with advancing age.