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K. Kogi, T. Sasaki
2001 Volume 30 Issue 1-2 Pages
1-2
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Kazutaka KOGI
2001 Volume 30 Issue 1-2 Pages
3-8
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Reflecting diversifying shift systems, extensive effort is put into managing shiftwork and reducing safety and health risks. It is accepted that shiftworkers are exposed to particular risks inherent in their irregular work schedules. This raises the question of how and to what extent we can ensure healthy work life for shiftworkers. In answering the question, we need to identify effective measures to improve both shiftworking conditions and the health of shiftworkers. Based on recent experiences in managing shiftwork, we note three directions of such measures: (a) comprehensive action to avoid risk-enhancing conditions based on general guidelines, (b) risk control as to workload, worksite ergonomics and risk reduction, and (c) support for flexible and restful working life. International standards are obviously relevant to these three aspects. Our own experiences in applying a set of ergonomic checkpoints to plant maintenance shiftwork demonstrate the usefulness of focusing on flexible work schedules and on multiple job-related factors such as night workload, ergonomic environment, resting conditions and training. There is a strong need for participatory planning and implementation of multi-area improvements as well as for relying on flexible schedules and autonomic teamwork. We may conclude that healthy shiftwork and healthy shiftworkers are compatible with each other only when certain conditions are met. In achieving this end, we need to combine (a) comprehensive measures to improve work schedules and job life, (b) strict risk management and (c) locally adjusted participatory steps for continual improvement.
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Peter KNAUTH
2001 Volume 30 Issue 1-2 Pages
9-14
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Implementation barriers may be caused by deficiencies in the knowledge, skills, motivation, or support of those involved in the process of implementation of a new shift system. There is no 'one and only' way of planning and implementing a new shift system. However, if the following factors of success are taken into consideration there is a better chance that workers will accept a new shift system: worker participation, information, communication, training, promoter commitment, professional project management, tailor-made solutions and an adequate organizational framework. These factors are particularly relevant in addressing barriers to the implementation of new shift systems. The most important measures to cope with resistance to change of shift systems are: worker participation, information, communication, training, promoter commitment, professional project management, tailor-made solutions and an adequate organizational framework.
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Giovanni COSTA
2001 Volume 30 Issue 1-2 Pages
15-20
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Johannes GAERTNER
2001 Volume 30 Issue 1-2 Pages
21-26
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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This paper starts with a discussion of computer aided shift scheduling. After a brief review of earlier approaches, two conceptualizations of this field are introduced: First, shift scheduling as a field that ranges from extremely stable rosters at one pole to rather market-like approaches on the other pole. Unfortunately, already small alterations of a scheduling problem (e.g., the number of groups, the number of shifts) may call for rather different approaches and tools. Second, their environment shapes scheduling problems and scheduling has to be done within idiosyncratic organizational settings. This calls for the amalgamation of scheduling with other tasks (e.g., accounting) and for reflections whether better solutions might become possible by changes in the problem definition (e.g., other service levels, organizational changes). Therefore shift scheduling should be understood as a highly connected problem. Building upon these two conceptualizations, a few examples of software that ease scheduling in some areas of this field are given and future research questions are outlined.
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Giovanni COSTA, Torbjorn ÅKERSTEDT, Friedhelm NACHREINER, Federi ...
2001 Volume 30 Issue 1-2 Pages
27-33
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Demand for flexible work hours (FWH) is increasing in Europe aimed at increasing the number of production hours on one hand, and, on the other, reducing individual working hours and/or increasing autonomy and control on them. In view of the lack of knowledge of the effects of FWH on health and safety, we started a pilot project, funded by the Joint Programme for Working Life Research in Europe (SALTSA), aimed at: a) comparing the most relevant national legislation and how the EU Directive 93/104 "concerning certain aspects of working time" has been implemented in the member States; b) reporting prevalence and trend of FWH in Europe according to the three EU Surveys on Working Conditions carried out in the last decade; c) collecting practical examples of innovative FWH; d) evaluating their impact on health and safety in relation to work sectors, job demands, social life, aging and gender. Consequent actions are going to include information and consultancy for pertinent authorities and social parties involved, as well as training programmes for Union officials and similar groups concerning the organisation of FWH according to ergonomic principles.
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Irja KANDOLIN, Mikko HÄRMÄ, Minna TOIVANEN
2001 Volume 30 Issue 1-2 Pages
35-40
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Flexibility of working hours became more prevalent in the 1990s in Finland. According to a representative survey on Finnish wage and salary earners (n=1790) at the beginning of 2000, a great majority of male (76%) and female (65%) employees regularly worked overtime and/or had irregular working hours every month. These employees were flexible in meeting the needs of their companies/employers. Individual flexibility of working hours was far less common, only one third of male and female employees were able to regulate their working hours. A better balance between company-controlled and individual flexibility would, however, improve the well-being of employees. Employees working overtime without being allowed to regulate their working hours felt more symptoms of distress and had more conflicts in combining workplace and family roles than those who could individually determine their working hours flexibly. An investment in individually determined flexibility, for example by means of participatory planning, would improve the well-being of employees, and thus also improve the productivity of the organization.
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Sophie PRUNIER-POULMAIRE, Charles GADBOIS
2001 Volume 30 Issue 1-2 Pages
41-46
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The reduction of the legal working week to 35 hours in France has generated wideranging social change. We examine the resulting changes in working-time patterns as well as their repercussions on the use of the time gained and on the quality of life and health. To compensate the reduction in the length of the working week, companies have modified the working-time patterns, by extending operation time (shiftwork, atypical schedules) and by matching the on-site workforce to production requirements (flexible working hours). They have sought to make more efficient use of working time: job intensification or job compression. The effects on the off-the-job life and health are linked to the shiftwork and atypical schedules designed to increase the company's operating time, and adjustments to the company's need for flexibilization impose working time/free time patterns that are at odds with biological rhythms and social life patterns. Changes to working-time patterns have unexpected consequences for work organization: heightened difficulties for the individual and the crew. These changes may generate a range of health problems related to overwork and stress. The way some companies have adapted may call into question the usefulness of work done by employees, thus damaging their social identity and mental well-being.
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Kerstin HÄNECKE, Hiltraud GRZECH-ŠUKALO, Corinna JAEGER
2001 Volume 30 Issue 1-2 Pages
47-52
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Examples of the design and implementation processes of flexible working time systems are derived from a counselling project in North Rhine-Westphalia, Germany. The practical cases shown represent a diversity of variable or flexible working time systems according to different branches and different anticipated aims to reach with flexibility. For companies flexibility should improve or at least consolidate their economic situation, and for employees flexibility should result in a beneficial effect on health, family and social life. Three examples of counselling practice are reported in this paper, each case representing a different approach to flexibility in working time. To avoid overtime an industrial production plant expanded the weekly operating time without increasing the employees working time. For this purpose shifts off had to be planned. To provide a continuous service one department of a service company changed from duty on call to regular shifts on weekends. Responsibility in handling the new working times was assigned to the team. In an old people's home working times were designed according to the irregular demands throughout the day, in combining full and part-time jobs adequately.
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Göran KECKLUND, Mirjam EKSTEDT, Torbjörn ÅKERSTEDT, An ...
2001 Volume 30 Issue 1-2 Pages
53-58
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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The aim of the present study was to investigate how "double-shifts" (15.5 hours) affects sleep, fatigue and self-rated health. The study was carried out on male construction workers of which 80% were long-distance commuters. The schedule involved two work periods and each work period involved two double shifts in a row. The subjects filled in a sleep/wake diary at 8 times across a year and a questionnaire at 3 times. They also wore an actigraph during one shift cycle. The results showed that sleepiness, and to a certain extent, mental fatigue increased during double shifts and accumulated across days. The short rest time (8.5 hours) between days caused insufficient sleep and approximately 5.5 hours of sleep was obtained between double shifts. Questionnaire data showed that complaints of insufficient sleep, exhaustion on awakening and pain symptoms increased across the year. It was concluded that a shift system involving double shifts has a negative effect on fatigue, recovery and health-related well-being.
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Lawrence SMITH, Paul NORMAN, Simon FOLKARD
2001 Volume 30 Issue 1-2 Pages
59-64
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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This research discusses the use and viability of the shiftwork locus of control construct alongside circadian type measures as a potential predictor of shiftwork-related outcomes. The shiftwork locus of control (SHLOC) scale, measures of circadian type and shiftwork-related outcome measures were completed by 100 shiftworkers on two occasions separated by seven months. The SHLOC scale measures shiftworkers' generalised beliefs about the levels of personal control they perceive in relation to four major functional domains commonly associated with shiftwork-related disruption. These domains include: sleep, social, health and work problems. The results of multivariate regression analysis showed the SHLOC scale to be predictive of the experience of shiftwork-related sleep and social-life problems while the circadian type measures were predictive of alertness at 7 months. The results suggest that a constellation of personality factors may be an important influence on an individual's tolerance to shiftwork
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Angela BAKER, Kathryn HEILER, Sally A. FERGUSON
2001 Volume 30 Issue 1-2 Pages
65-70
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The current study examined the impact on employee health and safety of changes to the roster system of an Australian coal mine. Absenteeism and incident frequency rate data were collected over a 33-month period that covered three different roster schedules, an 8-hour system, a 12-hour system and a 12-hour system incorporating unregulated overtime. The first change was implemented after consultation with the employee population, whereas the second was not. There were no significant negative effects of the 12-hour pattern, when compared to the 8-hour system. However, when unregulated and excessive overtime was introduced as part of the second round of changes, absenteeism rates were increased in one sector of the mine. The maintenance sector was subject to a significant increase in absenteeism rates, which may have been attributable to the excessive overtime required of the workers in that area. It is important that overtime be strictly monitored and that the employee population are involved in the process of roster change.
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Atsuko IKEGAMI, Akira NIWA
2001 Volume 30 Issue 1-2 Pages
71-76
Published: December 15, 2001
Released on J-STAGE: July 01, 2011
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Scheduling nurses to staff shifts is a major problem in hospitals. The necessity of maintaining a certain level of service and skill in the makeup of every shift, while balancing the workload among the nurses involved, is incredibly difficult. It is often impossible to develop a schedule which satisfies all the requirements despite the time and resources spent in the effort. This paper summarizes all our published research on nurse scheduling to date. The difficulties realized by our two investigations in Japan are shown first, together with a resulting scheduling problem. The nurse scheduling model based on the results is then described. In this model, all constraints are divided into two essentially different types; that which maintains a certain level of skill for each shift (‘shift constraints’) and that which concerns the workload for each nurse (‘nurse constraints’). By classifying the constraints in this manner, we can determine what is affected by a specific constraint when the constraint is not satisfied. We developed efficient algorithms while taking advantage of the structure of this model. Finally, it is shown that our algorithm can solve this problem for a 2-shift system efficiently.
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Philip TUCKER, Johannes GAERTNER, Carl MASON
2001 Volume 30 Issue 1-2 Pages
77-82
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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As with many forms of flexible working, Annualized Hours (AR) systems offer potential benefits to both the employer and the employee. However, the flexibility requirements of employers and employees often conflict. Therefore, when a large food manufacturing organization decided to redesign its AH system, it employed an independent consultancy to act as neutral third party. The consultancy provided technical expertise and assistance in developing an AH system that optimised productivity and was acceptable to the workforce. Data are presented, obtained from focus groups conducted throughout the organization, describing some of the potential difficulties of implementing an AH system. Drawing upon these data, a number of new AH systems were proposed and modelled using specialist software tools. The design process is described, together with the advantages and difficulties associated with use of the software tools. It is concluded that the key elements in the process of designing AH systems are centred around issues of trust and communication; the involvement of a broad range of interested parties, through a process of carefully managed group facilitation; and the need for adequate technical support in the development and evaluation of AH systems.
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Lawrence SMITH, Carl MASON
2001 Volume 30 Issue 1-2 Pages
83-87
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The reduction of exposure to longer runs of successive night duties is often one of the aims of 'best practice' intervention.. The objective of this pilot study was to examine the effects of a change in rota upon sleepiness and fatigue, and potential age-related issues in relation to the change. Participants were 102 police officers, mean age 33.60 (sd 6.11), mean shiftwork experience 10.56 years (sd 6.84). Testing occurred at least one month before the change from the existing 'Ottawa' system to a new rota that split a run of 7 consecutive night shifts into blocks of 3 and 4 within the rota cycle, and 6 months after the change. Measures of critical flicker fusion, subjective fatigue and sleepiness, and stimulant intake were taken in relation to selected night shifts on both rotas. Older officers tended to report higher fatigue and sleepiness, and higher caffeine intake than the younger shiftworkers irrespective of rota or shift. The findings tend to suggest that the change of rota had little effect but that age may play a substantial role in responses to night work.
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Simon FOLKARD, Joanne HILL
2001 Volume 30 Issue 1-2 Pages
89-95
Published: December 15, 2001
Released on J-STAGE: July 01, 2011
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This paper examines the possibility that we may be able to use subjective measures of perceived risk in order to assess the relative safety of different shift systems. A large-scale survey of safety-critical engineers included three items relating to risk on each shift, namely alertness, likelihood of making a mistake and confidence in driving home after it. These three measures were found to load on a separate factor for each shift. Hierarchical regression analyses indicated that perceived night shift risk could be predicted on the basis of circadian type, the extent to which the engineers could control their work schedule, and a number of features of the scheduled shift system. In most cases the relationships observed were reasonably consistent with established trends in either performance capability or accident and injury frequency. However, there were exceptions to this indicating that results based on measures of perceived risk should be interpreted with the utmost caution.
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Friedhelm NACHREINER
2001 Volume 30 Issue 1-2 Pages
97-102
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Reviewing the literature on time on task effects on safety shows contradictory evidence, especially with regard to 12h shifts. It is argued that this might depend on methodological problems associated with the analysis of accident data, e.g. selectivity of samples, validity of data bases and study designs, especially for analyses at the company level. Analyses of aggregated data seem to indicate an exponential increase of accident risk with time on task beyond the normal working day. This is supported by some recent studies based on data from the Federal Republic of Germany.
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Donald I. TEPAS
2001 Volume 30 Issue 1-2 Pages
103-106
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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For commercial transportation operations, around-the-clock operations are not a recent development. Despite the tenure of these practices, many accidents related to hours worked continue to be a problem. Although efforts by shiftwork experts to solve these problems are often mode specific, the transportation field does suggest several alternative approaches, which may be relevant to general shiftwork problems outside the transportation area. Four contemporary approaches to transportation shiftwork are discussed: environmental design, equipment design, organizational design, and information access systems. Examples are presented within each of these approaches.
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M.W. RAJARATNAM
2001 Volume 30 Issue 1-2 Pages
107-111
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Madeleine BOURDOUXHE, Georges TOULOUSE
2001 Volume 30 Issue 1-2 Pages
113-118
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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This paper presents selected results from a pilot research. The study of film technicians' work schedules and occupational hazards was based on a questionnaire administered to all 2200 film technicians (650 valid replies; response rate = 30%), interviews with producers and technicians on film-shooting organization and scheduling, courses in film technique, individual interviews with workers in trade at high risk, and review of the literature on freelancers, on the effects of intermittent work, and on risk factors for musculoskeletal injuries. Work schedules showed a tendency to extremely long work shifts (14 hours per day on average, and up to 19 hours in some trades). Occupational constraints and work schedules were found to relate to an increased risk of work-related injuries. Technicians identified fatigue associated with work schedules as the principal risk of accidents and one of the factors responsible for causing or aggravating their many musculoskeletal injuries. Work schedules were not the only cause of these injuries: stress - due to time constraints, work responsibilities and job insecurity - was also an important risk factor, consistent with the literature on musculoskeletal disorders. Physical workload was also problematic, particularly when demanding tasks had to be performed under severe time constraints.
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Hiltraud GRZECH-ŠUKALO, Kerstin HAENECKE, Corinna JAEGER
2001 Volume 30 Issue 1-2 Pages
119-124
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Since December 1998 a project of working time counselling named "Design of Modern Working Times" is supported by the federal state of North Rhine-Westphalia in Germany and the European Union; AWiS-consult is entrusted to carry out this project. The service offered to all companies, institutions, work committees, and employees interested covers information, assessment of existing working time schedules, development of alternative or new working time schedules, and accompanying implementation processes. Up to June 2001 nearly 300 inquiries were worked on, most of them from industry, service companies, and from the field of care and hospitals. Working time design in this project aims not only at work safety and health care but also at beneficial effects on employment. In a special campaign from May 2000 to May 2001, 61 companies were supported by AWiS-consult, with the result of more than 400 new employees and 16 companies with employment secured, so the combination of preventive health care and beneficial effects on employment by working time design can be assessed as successful.
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Gregory D. ROACH, Jill DORRIAN, Adam FLETCHER, Drew DAWSON
2001 Volume 30 Issue 1-2 Pages
125-130
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Laboratory studies have established that the performance impairments due to fatigue and alcohol consumption are quantitatively similar. However, the generalisability of this phenomenon is not clear because comparisons have not been made in realistic work settings with experienced shiftworkers. The aim of the current study was to quantify the effects of fatigue on performance in a simulated work environment (i.e. rail simulator) and compare them with the effects of alcohol consumption. It was hypothesised that fatigue would significantly impair driving performance, and that this impairment would be quantitatively similar to that associated with moderate levels of alcohol consumption. Twenty locomotive engineers participated in the study with a randomised cross-over design and three conditions: baseline, fatigue, and alcohol. During each 8-hour condition, participants completed four driving sessions in the rail simulator. The results indicate that fatigue caused participants to disengage from operating the simulator such that safety was traded off, not necessarily deliberately, against efficiency. The impairment in safety due to fatigue was in a range similar to the impairment associated with moderate levels of alcohol consumption. In summary, the study demonstrated that the effects of fatigue in a simulated work environment can be quantified and may be considerable.
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Alison ROGERS, Sharon HOLMES, Michael SPENCER
2001 Volume 30 Issue 1-2 Pages
131-136
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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A questionnaire study was conducted to obtain information from shiftworkers on the levels of tiredness experienced on the drive to and from work at different times of the day. The results demonstrated that, compared to non-shiftworkers, shiftworkers were more tired on the drive between their home and the workplace and more at risk of falling asleep behind the wheel. The main factors contributing to this increased level of sleepiness and associated driving impairment were the length of the sleep period prior to work, the type of shift and the travelling time. There was some evidence to suggest that on working days shiftworkers were more likely to be involved in an accident than non-shiftworkers. However, there were insufficient data to determine whether accidents were correlated with driver sleepiness.
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Nicole LAMOND, Jill DORRIAN, Gregory D. ROACH, Helen J. BURGESS, Alexa ...
2001 Volume 30 Issue 1-2 Pages
137-142
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The current study investigated changes in night-time performance, daytime sleep, and circadian phase during a week of simulated shift work. Fifteen young subjects participated in an adaptation and baseline night sleep, directly followed by seven night shifts. Subjects slept from approximately 0800hr until they naturally awoke. Polysomnographic data was collected for each sleep period. Saliva samples were collected at half hourly intervals, from 2000 hr to bedtime. Each night, performance was tested at hourly intervals. Analysis indicated that there was a significant increase in mean performance across the week. In general, sleep was not negatively affected. Rather, sleep quality appeared to improve across the week. However, total sleep time (TST) for each day sleep was slightly reduced from baseline, resulting in a small cumulative sleep debt of 3.53 (SD = 5.62) hours. Finally, the melatonin profile shifted across the week, resulting in a mean phase delay of 5.5 hours. These findings indicate that when sleep loss is minimized and a circadian phase shift occurs, adaptation of performance can occur during several consecutive night shifts.
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Maria NORDIN, Anders KNUTSSON
2001 Volume 30 Issue 1-2 Pages
143-147
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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The aims were to evaluate sleepiness and recovery during a schedule change, and during an 84-hours workweek. The control group (16 men) stayed on a six-week schedule, whereas the intervention group (12 men) transferred to a seven-week schedule. Sleepiness was estimated, using the KSS-scale, four times during the first and the third night in the fifth or sixth shift week. Recovery was assessed through four estimations on days one, three and five during the week off. Statistical testing was carried out using repeated measurement ANOVA. Sleepiness at night was affected by night (F=4.90, p<0.05) and hour (F=33.64, p<0.001) in both groups. The intervention group was sleepier during the first recovery day compared to the control group (F=4.02, p<0.05). Analysis of the 84-hour-week showed an effect of night (F=8.98, p<0.05) and hour (F=71.60, p<0.001) on night work, and day (F=22.49, p<0.01) and hour (F=6.66, p<0.05) on recovery. Sleepiness was more pronounced on the first recovery day (F=23.08, p<0.01). The seven-week schedule showed no effect that differed from that of the control group on sleepiness during the night shift. After the 84-hour workweek the workers recovered in about three days. The new schedules may affect the first recovery day negatively.
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Takayuki KAGEYAMA, Noriko NISHIKIDO, Toshio KOBAYASHI, Junko OGA, Miek ...
2001 Volume 30 Issue 1-2 Pages
149-154
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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A cross-sectional survey was carried out for the purpose of examining the association of work stress with insomnia among nurses working rotating shift systems. A self-administered questionnaire on sleep and mental health was distributed to 875 nurses at five hospitals in Japan. Out of the data from 785 (89.7%) respondents, those from 555 women engaged in rapidly and irregularly rotating shift systems as full-time nurses were examined. The prevalence of insomnia (29.2%) was three to four times higher than that in the general population. Among the insomniacs, 23% were current users of medically prescribed hypnotics. Multiple logistic analysis revealed that being 24 or less years old, working three or less night shifts per month, having six or less non-working days per month, receiving less support from colleagues and superiors, and taking care of severely ill patients were independent risk factors for insomnia. The number of hours of a night shift was found not associated with insomnia, taking the above variables into account. These results suggest that at least three factors, i.e., 1) young nurses not adapted to shiftwork, 2) the nurses requiring to remedy sleep deficits on non-working days, and 3) the work stress partly characteristic of nurses, have an adverse influence on their sleep.
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Frida Marina FISCHER
2001 Volume 30 Issue 1-2 Pages
155-160
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Pranab Kumar NAG, Anjali NAG
2001 Volume 30 Issue 1-2 Pages
161-166
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Valdo F. RODRIGUES, Frida Marina FISCHER, Mozar J. BRITO
2001 Volume 30 Issue 1-2 Pages
167-172
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Ton That KHAI, Tsuyoshi KAWAKAMI, Kazutaka KOGI
2001 Volume 30 Issue 1-2 Pages
173-178
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Adnyana MANUABA
2001 Volume 30 Issue 1-2 Pages
179-183
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Chalermchai CHAIKITTIPORN, Tsuyoshi KAWAKAMI, Kazutaka KOGI
2001 Volume 30 Issue 1-2 Pages
185-189
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Carlla SMITH, Robert GIBBY, Michael ZICKAR, Craig CROSSLEY, Chet ROBIE ...
2001 Volume 30 Issue 1-2 Pages
191-196
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Torbjorn ÅKERSTEDT, Birgitta OLSSON, Michael INGRE, Mikael HOLMG ...
2001 Volume 30 Issue 1-2 Pages
197-202
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Akinori NAKATA, Takashi HARATANI, Masaya TAKAHASHI, Norito KAWAKAMI, H ...
2001 Volume 30 Issue 1-2 Pages
203-209
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Sergio GARBARINO, Fabrizio DE CARLI, Barbara MASCIALINO, Manolo BEELKE ...
2001 Volume 30 Issue 1-2 Pages
211-216
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The aim of this study was to evaluate the effects of shiftwork on sleepiness, sleep disorders and sleep related accidents in a population of policemen. Data concerning age and physical characteristics, working conditions, sleep problems and accidents were collected by a questionnaire. Sleepiness was evaluated by the Epworth Sleepiness Scale (ESS) while the presence of sleep disorders was evaluated by a score (SD-score) drawn from indicators of insomnia, breathing disorders, periodic limb movements-restless leg syndrome and hypersomnia. The effects of age, gender, body mass index, working condition and seniority on ESS, SD-score and accidents were analysed by linear and logistic regression. Participants were 1280 policemen: 611 shiftworkers and 669 non-shiftworkers. The ESS scores were not higher in shiftworkers than in non-shiftworkers, but the SD-score was found to be significantly influenced by shiftwork condition and seniority. The occurrence of sleep-related accidents was found to have been significantly increased for shiftworkers and related to the presence of indicators of sleep disorders. The sleepiness could be underestimated or even overcome by the influence of stressing conditions. However our data should alert occupational health physicians for the diagnosis and prevention of possible lurking intrinsic sleep disorders likely to influence health problems and risk of accidents in shiftworkers.
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Lawrence SMITH, Carl MASON
2001 Volume 30 Issue 1-2 Pages
217-222
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Personality and experientially-based differences are suggested to moderate the negative effects of shiftworking. This investigation was one of a series of studies aimed at examining the relationship between internal locus of control (internality) and commonly reported outcomes of exposure to shiftworking. The study concentrated on whether or not shiftwork-specific internality appeared to be associated with better experiences for two groups of shiftworkers on different shift rotas. The Shiftwork Locus of Control (SHLOC) scale was completed by each group along with a range of outcome measures (including: sleep disturbance, alertness on shift, psychological well-being, disturbance of social and family life, and fatigue). The analyses controlled for for age, shiftwork experience and years of service effects. The results showed that for the majority of outcome variables, the higher internality was associated with significantly lower levels of shiftwork problems, especially when compared to the low internality group. The findings of this study further support the use of shiftwork-specific locus of control in shiftwork research as an indicator of potentially better tolerance, and possibly as part of an occupational heatlth monitoring process to aid the targeting of interventions.
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Alexandra L. HOLMES, Helen J. BURGESS, Kirsty McCULLOCH, Nicole LAMOND ...
2001 Volume 30 Issue 1-2 Pages
223-228
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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Shift workers encounter an increased risk of cardiovascular disease compared to their day working counterparts. To explore this phenomenon, the effects of one week of simulated night shift on cardiac sympathetic (SNS) and parasympathetic (PNS) activity were assessed. Ten (5m; 5f) healthy subjects aged 18-29 years attended an adaptation and baseline night before commencing one week of night shift (2300-0700h). Sleep was recorded using a standard polysomnogram and circadian phase was tracked using salivary melatonin data. During sleep, heart rate (HR), cardiac PNS activity (RMSSD) and cardiac SNS activity (pre-ejection period) were recorded. Night shift did not influence seep quality, but reduced sleep duration by a mean of 52±29 min. One week of night shift evoked a small chronic sleep debt of 5h 14±56 min and a cumulative circadian phase delay of 5h±14 min. Night shift had no significant effect on mean HR, but mean cardiac SNS activity during sleep was consistently higher and mean cardiac PNS activity during sleep declined gradually across the week. These results suggest that shiftwork has direct and unfavourableeffects on cardiac autonomic activity and that this might be one mechanism via which shiftwork increases the risk of cardiovascular disease. It is postulated that sleep losscould be one mediator of the association between shiftwork and cardiovascular health.
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Mina HA, Jaiyong KIM, Jungsun PARK, Ho Keun CHUNG
2001 Volume 30 Issue 1-2 Pages
229-233
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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This study examined the effects of shiftwork on the cardiovascular system. The blood pressure (BP) and heart rate variability (HRV) of 134 male workers, who worked 8- hour shifts with rapid rotation of shifts at 3-day intervals, were examined for all the three shifts. In addition, the job stress was measured by Karasek's JCQ 49-item questionnaire and the circadian type was assessed by the morningness-eveningness questionnaire. The smoking and alcohol drinking habits, marital status and past medical history were also obtained. The method of analyzing the measured data based on a mixed model was used to illustrate the association between the shiftwork duration and the BP or HRV. The average age of workers was 29 years (between 25- 44). Among them, 77.9% were current smokers, 50% showed the passive type of job strain in Karasek's model. The mean shiftwork duration was 5.21 years (range 5.4 months - 10 years). In the circadian type, none of them belonged to a definitely morning type or a definitely evening type. In the multivariate analysis adjusted by age, job strain, shift, circadian rhythm and smoking, the blood pressure showed significantly increasing trends according to shiftwork duration in both the systolic and diastolic BP. The heart rate variability also showed a significantly decreasing trend according to the shiftwork duration in both the parasympathetic and sympathetic functions (p<0.05). These results suggests that there are negative health effects arising from shiftwork on the cardiovascular system.
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Shuii SATO, Kazushi TAODA, Masanori KAWAMURA, Kinzou WAKARA, Yasuma FU ...
2001 Volume 30 Issue 1-2 Pages
235-240
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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We recorded ambulatory electrocardiograms of 6 long distance truck drivers during their work period in order to observe the affect of autonomic nervous function and symptoms while doing their work. We also recorded their work patterns every minute. The RRso value and the LFP/HFP ratio were calculated every two minutes based on R-R interval data. RR50 was significantly higher during taking naps than during other periods of work shifts, while, the LFP/HFP ratio showed significantly lower during taking naps than during other periods of work shifts. RRso in the morning was significantly higher than that in the afternoon. On the contrary, the LFP/HP ratio showed opposite tendency. Only on the times of driving, RRso was significantly higher in the morning than that in the afternoon. On the other hand, the LFP/HFP ratio showed an opposite tendency. These results show that the parasympathetic nervous activities were more dominant than sympathetic nervous activities in the morning during the subjects were doing long distance truck driving including midnight work. Driving while in high parasympathetic nervous activity levels may add to cardiovascular stress and lead to drowsiness. And this may result in disrupted attention. It is necessary to decrease work time and improve working conditions of truck drivers working long-hour shifts.
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Irena ISKRA-GOLEC
2001 Volume 30 Issue 1-2 Pages
241-244
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The study was designed to find out the cerebral hemispheres oscillations in stimuli processing during the 24-hour period of wakefulness in isolated subjects remaining in a monotonous environment. Stimuli processing speed from the 24-hour constant routine periods (06.00-06.00 h) of a larger experiment were analysed for the purpose of this paper. Parallel sets of words and pictures were exposed laterally using a purpose-designed computer program. The subjects reacted to pictures or words by pressing appropriate buttons. The significant dominant ultradian rhythms (around 4h) in the processing speed of words addressed to the right hemisphere were found and of pictures addressed to the left hemisphere. Longer significant dominant periodicities (around 12 h) appeared in the processing speed of words addressed to the left hemisphere and of pictures (around 8 h) addressed to the right hemisphere Ultradian rhythmicity of the central nervous system functioning is suggested.
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Thomas NESTHUS, Crystal CRUZ, Albert BOQUET, Cristy DETWILER, Kali HOL ...
2001 Volume 30 Issue 1-2 Pages
245-249
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The purpose of this study was to examine the circadian temperature rhythm in clockwise (CW) and counter-clockwise (CCW) rapidly rotating shift schedules. Arguments against the CCW rotation of shifts are that they result in shortened sleep and promote greater disruption of circadian rhythms. The 3-week study included a week of day shifts (0800-1600) and 2 weeks of shiftwork. The CW 2-2-1 schedule rotated from two early mornings (0600-1400) to two evenings (1400-2200) to one midnight shift (2200-0600) allowing 24 hours off at each shift rotation and a 48-hour weekend. The CCW schedule rotated from two evenings to two early mornings to one midnight shift allowing only 8 hours off at each shift rotation and an 80-hour weekend. Analysis of the 72-hr periods at the end of each workweek, including the midnight shifts and recovery periods during weeks 2 and 3 were compared to the same 72-hour period at the end of week 1 (baseline). A cosine function that fit the temperature curves by minimizing the sums of squares produced parameters that underwent analysis of covariance procedures. Significant differences were found between rotation conditions for amplitude and acrophase. An attenuation of amplitude and a delay in the acrophase was the found for the counter-clockwise condition. Features inherent in this schedule might explain these effects, particularly, the increased opportunity for "sleeping in" at the beginning of the week and an expanded (2-shift) workday at the end of the week.
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Hazuki YAMAUCHI, Mieko IWAMOTO, Noriaki HARADA
2001 Volume 30 Issue 1-2 Pages
251-254
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The purpose of this study was to assess the physiological effects of shift work on the urinary excretion rates of norepinephrine, 6-sulfatoxymelatonin and estriol in hospital nurses. Method: Twenty-four hour urine specimens were examined on a daytime/nighttime basis for each work shift of pregnant and non-pregnant subjects. The urinary norepinephrine and 6-sulfatoxymelatonin were measured by enzyme-linked immunosorbent assay and estriol by radio-immunoassay. Results: Urinary norepinephrine level during the night work was higher than the night levels of the days off and the day shift. Urinary 6-sulfatoxymelatonin level during the night work was lower than the night levels of the days off and the day shift. Urinary estriol level of pregnant subjects showed no differences among work shift and also between daytime and nighttime. Conclusions: Urinary excretion rates of norepinephrine and 6-sulfatoxymelatonin were affected by shift work both for non-pregnant and pregnant subjects. It was unlikely that urinary estriol levels in the pregnant subjects were significantly affected by shift work.
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Gregory D. ROACH, Helen BURGESS, Nicole LAMOND, Jill DORRIAN, Alexandr ...
2001 Volume 30 Issue 1-2 Pages
255-260
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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In most studies, the magnitude and rate of adaptation to various night work schedule is assessed using core body temperature as the marker of circadian phase. The ai: of the current study was to assess adaptation to a simulated night work schedule usir salivary dim light melatonin onset (DLMO) as an alternative circadian phase marke It was hypothesised that the night work schedule would result in a phase dela manifest in relatively later DLMO, but that this delay would be somewhat inhibit by exposure to natural light. Participants worked seven consecutive simulatf 8-hour night shifts (23:00-07:OOh). By night 7, there was a mean cumulative pha; delay of 5.5 hours, equivalent to an average delay of 0.8 hours per day. Th indicates that partial circadian adaptation occurred in response to the simulated nigJ work schedule. The radioimmunoassay used in the current study provides sensitive assessment of melatonin concentration in saliva that can be used 1 determine DLMO, and thus provides an alternative phase marker to core bod temperature, at least in laboratory studies.
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Irena ISKRA-GOLEC, Magdalena FAFROWICZ, Tadeusz MAREK, Giovanni COSTA, ...
2001 Volume 30 Issue 1-2 Pages
261-266
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Experiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post- treatment conditions.
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Jeffrey N. WHITMORE, Jonathan FRENCH, Joseph R. FISCHER
2001 Volume 30 Issue 1-2 Pages
267-272
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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This study compared the effects of a brief pulse (60-minute) of three full spectrum light intensities (1000, 500 and 30 lux) and two green light intensities (1000 and 500 lux) administered between 0200 and 0300 hrs. Ten participants were involved in this repeated measures study. Each participant experienced one condition every week for five weekends. Sessions began at 1800 hours and ended at 0600 hours the following day. Outside of the 60-minute exposure period, each session was spent in 30 lux white light. Oral temperature, salivary melatonin, cognitive performance and subjective mood were sampled throughout the sessions. Analysis revealed that all of the experimental light conditions significantly reduced salivary melatonin concentrations immediately following the pulse. This effect was not maintained beyond the duration of the light pulse. There was no significant effect on oral temperature. There were also no significant effects on cognitive performance and subjective mood, though some positive trends were observed. These results argue that brief, moderate intensity, pulses of either green or full spectrum light are sufficient to suppress the normal nocturnal rise in melatonin. However, the level of suppression obtained does not translate into significant improvement in cognitive performance or subjective mood.
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Tracey SLETTEN, Helen BURGESS, Natasha SAVIC, Saul GILBERT, Drew DAWSO ...
2001 Volume 30 Issue 1-2 Pages
273-278
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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Although melatonin has an important physiological role in the facilitation of sleep, its precise mechanism of action is not clear. To investigate the potential contribution of melatonin to influence cardiac autonomic activity in the evening, 16 young healthy subjects participated in a repeated measures design where cardiac autonomic activity, heart rate and blood pressure were examined during three experimental conditions. An initial baseline condition involved dim light exposure (<10 lux), permitting the normal nocturnal rise in endogenous melatonin. In other sessions, subjects were exposed to bright light (>3000 lux) to suppress melatonin secretion and administered a placebo or melatonin (5 mg) capsule at the estimated time of increase in endogenous melatonin (wake time + 14 hours). Heart rate, pre-ejection period (a measure of cardiac sympathetic activity) and respiratory sinus arrhythmia (a measure of parasympathetic activity) were not significantly altered in response to the three melatonin levels. While melatonin had no effect on diastolic blood pressure, systolic blood pressure was maximally decreased by 6 ± 1.93 mmHg (mean ± SEM, p<0.005) 150 minutes after exogenous melatonin. The results indicate that melatonin does not directly modulate cardiac autonomic activity, but may rather act directly on the cardiovascular system.
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Adam FLETCHER, Drew DAWSON
2001 Volume 30 Issue 1-2 Pages
279-285
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The authors have previously published the development and empirical validation of a work-related fatigue model. However, published work has not involved data from napping studies. The aim of this paper is to determine how closely the model predicts changes in subjective and objective measures from data published from napping studies. The regression results between the model outputs and logical reasoning, multiple sleep latency test scores, self-rated alertness, profile of mood state fatigue, visual vigilance and reaction time were all strong to very strong (R
2 = 0.4-0.9). Only digit symbol substitution revealed moderate (R
2 = 0.1-0.2) regression values. The outputs of the model reflect changes due to naps of varying duration and timing measured at varying periods following a nap. Together with the outputs from previous investigations, these results further support the potential use of the fatigue model in operational settings. This appears to be true in settings that utilise napping as well as those that do not.
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Mikko HÄRMÄ, Irja KANDOLIN
2001 Volume 30 Issue 1-2 Pages
287-293
Published: December 15, 2001
Released on J-STAGE: June 28, 2010
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The working population is aging fast in most European countries and in the USA. The health and well-being of an elderly shift worker depends on the interaction of several individual, medical, psychosocial and job-related factors. These factors are related to the biological ageing process, but also to changes in one's individual life situation and the needs of the ageing shift worker. The evidence of good age-specific solutions in working hours is limited, but the few published intervention studies support the use of individual flexibility, rapid forward rotating shift systems, and earlier shift start-end times in three-shift work. In addition to the development of shift schedules, the counter-measures to improve the health and well-being of ageing shift workers should be focused on the improvement of occupational health care and the promotion of appropriate coping mechanisms for the aging.
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Charles GADBOIS
2001 Volume 30 Issue 1-2 Pages
295-300
Published: December 15, 2001
Released on J-STAGE: February 23, 2011
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It is now recognized that the effects of nightwork result jointly from desynchronization of circadian rhythms and from the job content. In scheduling nightwork, use should be made of the shift systems most compatible with the biological rhythms and social patterns of the workers concerned, and specific measures should be implemented to reduce demands on nightworkers. Job content is of particular importance in the hospital sector, where demands vary greatly from one department to another. Above all, the tasks accomplished by those on nightshift differ markedly from those of daytime workers: nightwork is limited to scheduled health care jobs that cannot be deferred until the morning, and to management of incidents. Yet staffing levels at night are reduced. Certain daytime resources are lacking at night, and the working conditions, generally defined with reference to the activities of daytime personnel fail to take into account the specific features of nightwork which are largely ignored by the management. On the basis of various studies conducted in French hospitals (extensive questionnaire surveys, ergonomic analyses in different departments), these features of nightwork and the corresponding need for appropriate responses, in terms of shift systems and job content, are reviewed and discussed.
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