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Shiftwork: health, sleep and performance
ABSTRACTS Henley-on-Thames', takes the reader on a walk around the English town, as seen from an interface designer's point of view.
Work design and organization 23.5.44 (125960)
Costa, G, Cesana, G, Kogi, K and Wedderburn, A (eds) Shiftwork: health, sleep and performance Peter Lang, Frankfurt am Main (1990) 656 pp Shiftwork research is an astonishingly wide-ranging topic in two ways. Firstly, it uses information from research in a very wide range of basic disciplines: from chronology and sleep research to sociology and dietetics, psychology and physiology. As a consequence of this, good researchers need to have some awareness of findings in disciplines other than their own, so that the one clear aim of the series of symposia on shiftwork is to meet this need. This volume comprises the proceedings of the ninth symposium. 23.5.45 (125984)
Samuel, A, Wegnmnn, H M, Vejvoda, M, Maass, H, Gundel, A and Schutz, M 'Influence of melatonin treatment on human circadian rhythmicity before and after a simulated 9-hr time shift' J Biol Rhythms Vol 6 No 3 (1991) pp 235-248 (39 refs) The hormone melatonin is currently proposed by some investigators to be an efficient means for decreasing the impairing effects of jet lag. Eight healthy male subjects, aged 20-32, underwent a 9 h advance shift in the isolation facility of the institute during two periods each of 15 days' duration. In a double-blind, crossover design, subjects took either melatonin or placebo at 1800 h local time for 3 d before the time shift and at 1400 h for 4 d afterwards. The time shift was simulated on days 7 and 8 by shortening the sleep period by 6 h and the following wake period by 3 h. Body temperature was recorded every 90 min, and urine was collected at 3 h intervals all day and night. Melatonin treatment enhanced the resynchronization speed of some, but not all, hormone and electrolyte excretion rates for several days after the time shift. The adaptation speed of the temperature rhythm significantly increased during one postshift day. In addition, the circadian temperature rhythm had a significantly higher amplitude under melatonin treatment than under placebo after the time displacement. For the placebo group, the rhythm of 6-hydroxymelatoninsulfate excretion exhibited an advance shift in five subjects, whereas the other three 356
showed a delay shift, and adjustment did not achieve more than one-half of the expected value within 8 d. A significantly different adjustment could be observed in the melatonin-treated group: seven subjects underwent an advance shift of the expected 9 h within an average of 8 d. The results suggest that melatonin treatment can accelerate resynchronization of the melatonin excretion rhythm after eastward timezone transitions. The improvement is not, however, sufficiently great that melatonin can be recommended for the alleviation of jet lag.
23.5.46 (125991)
Deigado, E, Bustos, T and Genaidy, AM 'Active microbreaks effects on musculoskeletal discomfort perceived in meatpacking plants' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety IIl Taylor & Francis, London (1991) pp 137-142 (2 refs) This study was conducted to examine whether a system of active microbreaks can reduce the discomfort perceived by employees in a meatpacking plant. Results indicated that active microbreaks significantly reduced the level of discomfort perceived by employees during the course of the working day. Thus, it is recommended that this intervention be tested to determine if it can reduce the frequency and severity of injuries and illnesses in the meatpacking industry.
23.5.47 (126008)
Maline, J and Dorval, P 'The analysis of crew working operations: an implement for improving fishing vessel design (Analyse du travail d'un equipage: prise en compte de l'activit6 des marins-pecheurs pour conqevoir leur espace de travail)' (in French) Tray Hum Vol 54 No 2 (1991) pp 165-184 (7 refs) Mechanisms determining the working activity of a trawler crew have been studied on board during three trips of 15 days each. The simultaneous occupation of space for different types of activity has been analysed according to the occurrence or not of incidents when gear handling. Though limited - having been carried out on one type of fishing vessel - this study defines several criteria for the evaluation of working places which are to be taken into account for the design of trawlers. Those criteria are all the more relevant because they are issued from the analysis of the way the working activity is operated by the crew, as a whole.
23.5.48 (126232)
Dadoy, M 'The role of job analysis in job evaluation (Role et place de l'analyse du travail dans les syst~mes d'evaluation de la qualification du travail)' (in French) Tray Hum Vol 54 No 2 (1991) pp 92112 (31 refs) Job analysis is required for job evaluation. What type of job analysis is used? What principles are the basis for setting wage rates? What is the role of work analysis in the social stratification? The purpose of job evaluation is to appreciate, not only the value of each worker, in relation to others on the labour market, but also the skills required for the job, in comparison with the skills needed for other jobs in the company. The idea is that personnel specifications can be identified by careful study of the job. The first step in this process is to obtain a thorough job description, ie a detailed statement of what must be done by the man on the job. Job description is not job analysis; it refers to instructions, theoretical working. This kind of job analysis can be a good tool, in a country such as the USA, where the labour market dominates the setting of wage rates. But what is the practice of job evaluation in France? Workplaces take the place of jobs. The employers' purpose is supposed to evaluate skills required by a particular workplace, because of the specificity of the working process in each company. In fact, French employers want to preserve the autonomy of their wages policy from the labour market's influence. They want individualized wages. So, it is logical that an analysis of the real activities and abilities of each operator takes the place of the job description. But, with this method, there are too many chances of not getting the desired wage range. Hierarchy is not the result of analysing the real working procedures and activities; hierarchy is the first principle; it is the real purpose. Methods for getting accurate information about personnel and their skills must be directed to one purpose: the division of manpower, wage range, social stratification. Then, only pseudo-analyses of working are applied. So, the only techniques practised are short interviews with operators, because it is well known that it is difficult for the operator to speak about work. The purpose of this paper is not to attack interviews. Interviews are a very good tool for obtaining relevant data about working, when they are very long and thorough, compared with many other approaches to work. But in job evaluation, as practised in France, short interviews are the better means for showing that hierarchy is 'natural'. Applied Ergonomics
Work design and organization 23.5.44 (125960)
Costa, G, Cesana, G, Kogi, K and Wedderburn, A (eds) Shiftwork: health, sleep and performance Peter Lang, Frankfurt am Main (1990) 656 pp Shiftwork research is an astonishingly wide-ranging topic in two ways. Firstly, it uses information from research in a very wide range of basic disciplines: from chronology and sleep research to sociology and dietetics, psychology and physiology. As a consequence of this, good researchers need to have some awareness of findings in disciplines other than their own, so that the one clear aim of the series of symposia on shiftwork is to meet this need. This volume comprises the proceedings of the ninth symposium. 23.5.45 (125984)
Samuel, A, Wegnmnn, H M, Vejvoda, M, Maass, H, Gundel, A and Schutz, M 'Influence of melatonin treatment on human circadian rhythmicity before and after a simulated 9-hr time shift' J Biol Rhythms Vol 6 No 3 (1991) pp 235-248 (39 refs) The hormone melatonin is currently proposed by some investigators to be an efficient means for decreasing the impairing effects of jet lag. Eight healthy male subjects, aged 20-32, underwent a 9 h advance shift in the isolation facility of the institute during two periods each of 15 days' duration. In a double-blind, crossover design, subjects took either melatonin or placebo at 1800 h local time for 3 d before the time shift and at 1400 h for 4 d afterwards. The time shift was simulated on days 7 and 8 by shortening the sleep period by 6 h and the following wake period by 3 h. Body temperature was recorded every 90 min, and urine was collected at 3 h intervals all day and night. Melatonin treatment enhanced the resynchronization speed of some, but not all, hormone and electrolyte excretion rates for several days after the time shift. The adaptation speed of the temperature rhythm significantly increased during one postshift day. In addition, the circadian temperature rhythm had a significantly higher amplitude under melatonin treatment than under placebo after the time displacement. For the placebo group, the rhythm of 6-hydroxymelatoninsulfate excretion exhibited an advance shift in five subjects, whereas the other three 356
showed a delay shift, and adjustment did not achieve more than one-half of the expected value within 8 d. A significantly different adjustment could be observed in the melatonin-treated group: seven subjects underwent an advance shift of the expected 9 h within an average of 8 d. The results suggest that melatonin treatment can accelerate resynchronization of the melatonin excretion rhythm after eastward timezone transitions. The improvement is not, however, sufficiently great that melatonin can be recommended for the alleviation of jet lag.
23.5.46 (125991)
Deigado, E, Bustos, T and Genaidy, AM 'Active microbreaks effects on musculoskeletal discomfort perceived in meatpacking plants' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety IIl Taylor & Francis, London (1991) pp 137-142 (2 refs) This study was conducted to examine whether a system of active microbreaks can reduce the discomfort perceived by employees in a meatpacking plant. Results indicated that active microbreaks significantly reduced the level of discomfort perceived by employees during the course of the working day. Thus, it is recommended that this intervention be tested to determine if it can reduce the frequency and severity of injuries and illnesses in the meatpacking industry.
23.5.47 (126008)
Maline, J and Dorval, P 'The analysis of crew working operations: an implement for improving fishing vessel design (Analyse du travail d'un equipage: prise en compte de l'activit6 des marins-pecheurs pour conqevoir leur espace de travail)' (in French) Tray Hum Vol 54 No 2 (1991) pp 165-184 (7 refs) Mechanisms determining the working activity of a trawler crew have been studied on board during three trips of 15 days each. The simultaneous occupation of space for different types of activity has been analysed according to the occurrence or not of incidents when gear handling. Though limited - having been carried out on one type of fishing vessel - this study defines several criteria for the evaluation of working places which are to be taken into account for the design of trawlers. Those criteria are all the more relevant because they are issued from the analysis of the way the working activity is operated by the crew, as a whole.
23.5.48 (126232)
Dadoy, M 'The role of job analysis in job evaluation (Role et place de l'analyse du travail dans les syst~mes d'evaluation de la qualification du travail)' (in French) Tray Hum Vol 54 No 2 (1991) pp 92112 (31 refs) Job analysis is required for job evaluation. What type of job analysis is used? What principles are the basis for setting wage rates? What is the role of work analysis in the social stratification? The purpose of job evaluation is to appreciate, not only the value of each worker, in relation to others on the labour market, but also the skills required for the job, in comparison with the skills needed for other jobs in the company. The idea is that personnel specifications can be identified by careful study of the job. The first step in this process is to obtain a thorough job description, ie a detailed statement of what must be done by the man on the job. Job description is not job analysis; it refers to instructions, theoretical working. This kind of job analysis can be a good tool, in a country such as the USA, where the labour market dominates the setting of wage rates. But what is the practice of job evaluation in France? Workplaces take the place of jobs. The employers' purpose is supposed to evaluate skills required by a particular workplace, because of the specificity of the working process in each company. In fact, French employers want to preserve the autonomy of their wages policy from the labour market's influence. They want individualized wages. So, it is logical that an analysis of the real activities and abilities of each operator takes the place of the job description. But, with this method, there are too many chances of not getting the desired wage range. Hierarchy is not the result of analysing the real working procedures and activities; hierarchy is the first principle; it is the real purpose. Methods for getting accurate information about personnel and their skills must be directed to one purpose: the division of manpower, wage range, social stratification. Then, only pseudo-analyses of working are applied. So, the only techniques practised are short interviews with operators, because it is well known that it is difficult for the operator to speak about work. The purpose of this paper is not to attack interviews. Interviews are a very good tool for obtaining relevant data about working, when they are very long and thorough, compared with many other approaches to work. But in job evaluation, as practised in France, short interviews are the better means for showing that hierarchy is 'natural'. Applied Ergonomics