Introduction: Aging and the Multifaceted Influences on Adaptation to Working Time

This special issue of Chronobiology International presents a selection of papers originally delivered at the 18th International Symposium on Shift Work and Working Time, held at Yeppoon, Australia, in August 2007. The key theme of the symposium was “Aging and Working Time: Creating Safe Environments.” Older workers are widely believed to experience greater difficulty than younger workers adapting to shift work and irregular work schedules. However, while the three reviews of age effects published here (Costa & Di Milia, ; Folkard, ; Gander & Signal, ) identify evidence that older workers do indeed adapt less well, they also demonstrate that much more research is urgently required. The remaining papers address various aspects of the impact of work schedules on health, safety, sleep, and performance. They can be divided into three broad categories: circadian and other periodic factors; sleep, sleepiness, and fatigue; and other aspects of health and adjustment. This collection of papers showcases the best of contemporary research on the safety and health effects of working hours, continuing the tradition established by the two previous issues of the journal devoted to earlier symposia on shift work and working time.     

Flexible Working Hours,Health, and Well-Being in Europe: Some Considerations from a SALTSA Project

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the “company-based flexibility” and the “individual-oriented flexibility”; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and “irregular” working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic research and well-controlled actions in order to examine in detail what flexible working hours are considered, what and where are their positive effects, in particular, as concerns autonomy, and what regulation seem most reasonable.     

The 24-hour society between myth and reality

The 24-hour society appears to be an ineluctable process towards a social organisation where time constraints are no more "restricting" the human life. But, what kind of 24-hour society do we need? At what costs? Are they acceptable/sustainable? Shift work, night work, irregular and flexible working hours, together with new technologies, are the milestone of this epochal passage, of which shift workers are builders and victims at the same time. The borders between working and social times are no more fixed and rigidly determined: not only the link between work place and working hours is broken, but also the value of working time changes according to the different economic/productive/social effects it can make. What are the advantages and disadvantages for the individual, the companies, and the society? What is the cost/benefit ratio in terms of physical health; psychological well-being, family and social life? The research on irregular working hours and health shows us what can be the negative consequences of non-human-centered working times organisations. Coping properly with this process means avoiding a passive acceptance of it with consequent maladjustments at both individual and social level, but adopting effective preventive and compensative strategies aimed at building a more sustainable society, at acceptable costs and with the highest possible benefits.     

Payroll data based description of working hours in the Danish regions

ABSTRACT

The aim was to describe the organization of working hours in the Danish regions according to sex, age and calendar year. Based on the Danish Working Hour Database (DWHD), individuals were classified according to schedules: Permanent day (57.8%), evening (1.7%), or night (1.2%); day/evening (22.0%); day/night (6.6%); evening/night (0.6%); and day/evening/night (10.2%). More men (9.1%) than women (5.9%) worked day/night, whereas more women (10.9%) than men (7.4%) worked day/evening/night. More young than older employees worked day/evening/night, and fewer worked permanent day or night. From 2008 to 2015 we observed a trend towards more employees working permanent day and fewer employees working other schedules. Altogether DWHD provides a strong tool in research on working hours.     

Diurnal urinary 6-sulfatoxymelatonin levels among healthy Danish nurses during work and leisure time

The present study aims to examine the influence of evening and night shift work, compared to day shift work, on melatonin secretion in nurses in a field setting. Effects were examined during a workday and during a day off. Both fixed schedules and mixed or rotating schedules were studied. In total, 170 nurses were studied: 89 nurses worked fixed schedules, 27 nurses worked the day shift, 12 nurses worked the evening shift, 50 nurses worked the night shift, and 82 nurses worked mixed schedules, with data collected during a day (n=17), evening (n=14), or night shift (n=50). All spot urine samples were collected during 24 h from the participants on a work day and on a day off and were analyzed for 6-sulphatoxymelatonin. On the day of urine sampling, participants filled in the Karolinska Sleep Diary. Additional information was collected through a telephone interview. Data were analyzed using a mixed procedure with autoregressive covariance structure. The present study showed that shift work affected the concentrations of 6-sulphatoxymelatonin in the short term by lower excretion in urine from nurses working the night compared to day shift on a workday and on a day off as well. No significant differences were observed between a workday and a day off when doing day and evening shifts, irrespective of mixed and fixed schedules. Sleep length was reduced workdays (from 6.1-6.8 h) among all nurses, compared to days off (from 7.8-8.7 h).     

Flexible working hours, health, and well-being in Europe: some considerations from a SALTSA project

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the “company-based flexibility” and the “individual-oriented flexibility”; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and “irregular” working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic research and well-controlled actions in order to examine in detail what flexible working hours are considered, what and where are their positive effects, in particular, as concerns autonomy, and what regulation seem most reasonable.     

Factors Associated With Shift Work Disorder in Nurses Working With Rapid-Rotation Schedules in Japan: The Nurses’ Sleep Health Project

Workers who meet the criteria for shift work disorder (SWD) have elevated levels of risk for various health and behavioral problems. However, the impact of having SWD on shiftworkers engaged in rapid-rotation schedules is unknown. Moreover, the risk factors for the occurrence of SWD remain unclear. To clarify these issues, we conducted a questionnaire-based, cross-sectional survey on a sample of shiftworking nurses. Responses were obtained from 1202 nurses working at university hospitals in Tokyo, Japan, including 727 two-shift workers and 315 three-shift workers. The questionnaire included items relevant to age, gender, family structure, work environment, health-related quality of life (QOL), diurnal type, depressive symptoms, and SWD. Participants who reported insomnia and/or excessive sleepiness for at least 1 mo that was subjectively relevant to their shiftwork schedules were categorized as having SWD. The prevalence of SWD in the sampled shiftworking nurses was 24.4%; shiftworking nurses with SWD showed lower health-related QOL and more severe depressive symptoms, with greater rates of both actual accidents/errors and near misses, than those without SWD. The results of logistic regression analyses showed that more time spent working at night, frequent missing of nap opportunities during night work, and having an eveningness-oriented chronotype were significantly associated with SWD. The present study indicated that SWD might be associated with reduced health-related QOL and decreased work performance in shiftworking nurses on rapid-rotation schedules. The results also suggested that missing napping opportunities during night work, long nighttime working hours, and the delay of circadian rhythms are associated with the occurrence of SWD among shiftworking nurses on rapid-rotation schedules. (Author correspondence: yuinoue@tokyo-med.ac.jp)     

The interference of flexible working times with the circadian temperature rhythm--a predictor of impairment to health and well-being?

In order to analyze whether impairments to health and well-being under flexible working hours can be predicted from specific characteristics of the work schedules, periodic components in flexible working hours and their interference with the circadian temperature rhythm were analyzed applying univariate and bivariate spectrum analyses to both time series. The resulting indicators of spectral power and phase shift of these components were then related to reported health impairments using regression analysis. The results show that a suppression of both the 24 and the 168 h components in the work schedules (i.e., a lack of periodicity) can be used to predict reported health impairments, and that if there are relatively strong 24 and 168 h components left in the work schedules, their phase difference with the temperature rhythm (as an indicator of the interference between working time and the circadian rhythm) further predicts impairment. The results indicate that the periodicity of working hours and the amount of (circadian) desynchronization induced by flexible work schedules can be used for predicting the impairing effects of flexible work schedules on health and well-being. The results can thus be used for evaluating and designing flexible shift rosters.     

SHIFTWORK,WORK-FAMILY CONFLICT AMONG ITALIAN NURSES,AND PREVENTION EFFICACY

Shiftwork may be a demanding situation because it raises problems for reconciling work and nonwork activities; as such, this conflict may be mitigated by designing and implementing effective preventative actions at the workplace. There is a paucity of research directly examining the impact of work schedules and preventative measures at work on work-family conflict. Hence, the authors posed the following questions in their study: What is the impact of different work schedules on work-family conflict? Is a preventative culture associated with less work-family conflict? Is work-family conflict associated with specific health and well-being indicators and if so, how does work-family conflict affect well-being as compared with other potential determinants? A subset of 750 nurses (≈10% of total workforce) were randomly selected from a larger sample. Nurses completed the Italian version of the NEXT questionnaire plus newly developed items to create an index on occupational safety and health prevention at work. Data were explored using two data mining techniques, Random Forests and Bayesian Networks, and modeled using hierarchical linear regression models. In all, 664 (88.5% of sample) nurses answered the questionnaire. The authors found that different work schedules had a differential impact on work-family conflict. In addition, effective risk communication between workers and people in charge of safety and health, and participation in preventative activities, quantitative workload, performing tasks not belonging to the nursing profession, and the number of weekends/month spent at work were all strongly associated with work-family conflict. The variable “time schedules” also acted as an effect modifier in the relationship between effective communication and participation in preventative activities and work-family conflict. In addition, quantitative demands played a role as a mediator (30% of total effect) in the relationship between effective communication and participation in preventative activities and work-family conflict. Work-family conflict was significantly associated with burnout, sleep, and presenteeism; its association with burnout was higher than other precursors. Shift schedules that involved night work implied different workload demands, less effective communication, and participation in preventative activities than the other work schedules considered. The presence of a preventative culture directly reduced work-family conflict and indirectly via reduction of work demands. The authors conclude that the development of a preventative culture among irregular and night shiftworkers can be effective in reducing work-family conflict, while positively increasing well-being and job performance. (Author correspondence: donatella.camerino@unimi.it)     

Diurnal Urinary 6‐Sulfatoxymelatonin Levels among Healthy Danish Nurses during Work and Leisure Time

The present study aims to examine the influence of evening and night shift work, compared to day shift work, on melatonin secretion in nurses in a field setting. Effects were examined during a workday and during a day off. Both fixed schedules and mixed or rotating schedules were studied. In total, 170 nurses were studied: 89 nurses worked fixed schedules, 27 nurses worked the day shift, 12 nurses worked the evening shift, 50 nurses worked the night shift, and 82 nurses worked mixed schedules, with data collected during a day (n=17), evening (n=14), or night shift (n=50). All spot urine samples were collected during 24 h from the participants on a work day and on a day off and were analyzed for 6‐sulphatoxymelatonin. On the day of urine sampling, participants filled in the Karolinska Sleep Diary. Additional information was collected through a telephone interview. Data were analyzed using a mixed procedure with autoregressive covariance structure. The present study showed that shift work affected the concentrations of 6‐sulphatoxymelatonin in the short term by lower excretion in urine from nurses working the night compared to day shift on a workday and on a day off as well. No significant differences were observed between a workday and a day off when doing day and evening shifts, irrespective of mixed and fixed schedules. Sleep length was reduced workdays (from 6.1–6.8 h) among all nurses, compared to days off (from 7.8–8.7 h).     

Work Ability of Health Care Shift Workers: What Matters?

This paper aims at identifying variables associated with inadequate work ability among nursing personnel at a public hospital, considering factors related to socio‐demographic, lifestyles, working conditions, and health outcomes. A cross‐sectional study was conducted in a university hospital in São Paulo, Brazil, as part of a larger research study on tolerance to 12 h night work. Nursing staff included registered nurses, nurse technicians, and nurse aides; in total, there were 996 healthcare workers (878 female; 118 male) at the time of the study. Some 696 workers (69.9%) of the population agreed to participate. Data collection (October 2004–July 2005) was based on a comprehensive questionnaire about living and working conditions (including incivility at work, work demands, work control, and support), mental and physical health symptoms (fatigue and sleep problems), and work ability. This report presents analyses of the adapted Brazilian version of the Work Ability Index (WAI) and associated variables. The study population worked one of the following shift schedules at this hospital: 12 h nights followed by 36 h off or 9 h or 6 h day (morning or afternoon) shifts. The mean age of the respondents was 34.9 (S.D.±10.4) years of age; 31.5% of the participants held two jobs. Statistical analyses using a hierarchical multiple logistic regression model were performed to evaluate the factors associated with inadequate (moderate and low scores) of the WAI. The significantly associated factors were socio‐demographic (income responsibility, sole breadwinner, raising kids, age group), working conditions (thermal discomfort, organization of the workplace, and verbal abuse), and health outcomes (high body mass index, obesity, sleep problems, and fatigue). In spite of limitations of the study design, results indicate that the nursing profession is associated with stressful working conditions, contributing to inadequate WAI. This is in addition to bad living conditions and precarious work. Intervention measures, either at the workplace or at individual levels, are necessary to prevent a decrease in work ability, even in this quite young working population.     

Influence of flexibility and variability of working hours on health and well-being

Flexible working hours can have several meanings and can be arranged in a number of ways to suit the worker and/or employer. Two aspects of “flexible” arrangement of working hours were considered: one more subjected to company control and decision (variability) and one more connected to individual discretion and autonomy (flexibility). The aim of the study was to analyze these two dimensions in relation to health and well-being, taking into consideration the interaction with some relevant background variables related to demographics plus working and social conditions. The dataset of the Third European Survey on working conditions, conducted in 2000 and involving 21,505 workers, was used. Nineteen health disorders and four psycho-social conditions were tested by means of multiple logistic regression analysis, in which mutually adjusted odds ratios were calculated for age, gender, marital status, number of children, occupation, mode of employment, shift work, night work, time pressure, mental and physical workload, job satisfaction, and participation in work organization. The flexibility and variability of working hours appeared inversely related to health and psycho-social well-being: the most favorable effects were associated with higher flexibility and lower variability. The analysis of the interactions with the twelve intervening variables showed that physical work, age, and flexibility are the three most important factors affecting health and well-being. Flexibility resulted as the most important factor to influence work satisfaction; the second to affect family and social commitment and the ability to do the same job when 60 years old, as well as trauma, overall fatigue, irritability, and headache; and the third to influence heart disease, stomachache, anxiety, injury, and the feeling that health being at risk because of work. Variability was the third most important factor influencing family and social commitments. Moreover, shift and night work confirmed to have a significant influence on sleep, digestive and cardiovascular troubles, as well and health and safety at work. Time pressure also showed a relevant influence, both on individual stress and social life. Therefore, suitable arrangements of flexible working time, aimed at supporting workers' coping strategies, appear to have a clear beneficial effect on worker health and well-being, with positive consequences also at the company and social level, as evidenced by the higher “feeling to be able to work until 60 years of age”.     

20th International Symposium on Shiftwork and Working Time: Biological Mechanisms,Recovery, and Risk Management in the 24-h Society

This dedicated issue of Chronobiology International is devoted to the selected proceedings of the 20th International Symposium on Shift Work and Working Time held in Stockholm, Sweden, 28 June to 1 July 2011. It constitutes the fifth such issue of the journal since 2004 dedicated to the selected proceedings to the meetings of the Working Time Society. The key theme of the 20th Symposium was “Biological Mechanisms, Recovery, and Risk Management in the 24-h Society.” The collection of papers of this dedicated issue represents the best of contemporary research on the effects of night and rotating shift schedules on worker health and safety. The contents cover such topics as sleep restriction, injuries, health, and performance of night work and rotating shiftwork, plus light treatment as a countermeasure against the circadian disruption of shiftwork. The majority of the papers are observational field studies, including some of large sample size, and three studies are well-designed laboratory experiments. (Author correspondence: goran.kecklund@stress.su.se)     

DEPRESSED MOOD IN THE WORKING POPULATION: ASSOCIATIONS WITH WORK SCHEDULES AND WORKING HOURS

The impact of working time arrangements (WTA) on health has been studied extensively. Still, little is known about the interrelation between work schedules, working hours, and depressed mood. For work schedules, the underlying assumptions regarding depressed mood refer to a disturbance of social and biological rhythms, whereas for working hours, the assumptions relate to workload and work capacity. Conversely, depressed mood may urge an employee to adjust his/her work schedule and/or number of working hours/week (h/wk). The aim of this study was to assess the association between work schedule and working hours with depressed mood. Using baseline data from the Maastricht Cohort Study, depressed mood in day work was compared with depressed mood in different shiftwork schedules (n?=?8843). Within day work, several categories of working h/wk were studied in association with depressed mood (n?=?7217). The association between depressed mood and several aspects of overtime was assessed separately. Depressed mood was measured with a dichotomous item: “Did you feel down every day over the last two weeks?” Separate logistic regression analyses were conducted for men and women, with adjustments for potential confounders. The odds ratio (OR) for depressed mood was greater for men involved in shiftwork than for men only involved in day work (three-shift OR?=?2.05 [95% confidence interval, CI 1.52–2.77]; five-shift OR?=?1.34 [95% CI 1.00–1.80]; irregular-shift OR?=?1.79 [95% CI 1.27–2.53]). In female employees, five-shift work was associated with a higher prevalence of depressed mood (OR?=?5.96 [95% CI 2.83–12.56]). Regarding the number of working h/wk, men working <26?h/wk had a higher prevalence of depressed mood than men working 36–40?h/wk (OR?=?2.73 [95% CI 1.35–5.52]). After conducting trend analyses, a significant decreasing trend was found in men, whereas an increasing trend was found in women working a high number of hours. Furthermore, a dose-response relationship was present in men regarding the number of overtime h/wk. This study showed that different work schedules and working hours are associated with depressed mood. Shiftwork was related to a higher prevalence of depressed mood than day work. The association was more pronounced for male employees. Regarding the number of working h/wk, male and female employees showed an opposite trend in depressed mood. Because of the possibility of a healthy worker effect and the possibility of a reciprocal relationship between WTA and depressed mood, the reported relation might be underestimated. This study has illustrated that occupational physicians, who deal with depressed mood among workers, should carefully consider the impact of WTA. (Author coorespondence: Karolien.Driesen@epid.unimaas.nl)     

Exploring sleepiness and entrainment on permanent shift schedules in a physiologically based model

The effects of permanent shift work on entrainment and sleepiness are examined using a mathematical model that combines a model of sleep-wake switch in the brain with a model of the human circadian pacemaker entrained by light and nonphotic inputs. The model is applied to 8-hour permanent shift schedules to understand the basic mechanisms underlying changes of entrainment and sleepiness. Average sleepiness is shown to increase during the first days on the night and evening schedules, that is, shift start times between 0000 to 0700 h and 1500 to 2200 h, respectively. After the initial increase, sleepiness decreases and stabilizes via circadian re-entrainment to the cues provided by the shifts. The increase in sleepiness until entrainment is achieved is strongly correlated with the phase difference between a circadian oscillator entrained to the ambient light and one entrained to the shift schedule. The higher this phase difference, the larger the initial increase in sleepiness. When entrainment is achieved, sleepiness stabilizes and is the same for different shift onsets within the night or evening schedules. The simulations reveal the presence of a critical shift onset around 2300 h that separates schedules, leading to phase advance (night shifts) and phase delay (evening shifts) of the circadian pacemaker. Shifts starting around this time take longest to entrain and are expected to be the worst for long-term sleepiness and well-being of the workers. Surprisingly, we have found that the circadian pacemaker entrains faster to night schedules than to evening ones. This is explained by the longer photoperiod on night schedules compared to evening. In practice, this phenomenon is difficult to see due to days off on which workers switch to free sleep-wake activity. With weekends, the model predicts that entrainment is never achieved on evening and night schedules unless the workers follow the same sleep routine during weekends as during work days. Overall, the model supports experimental observations, providing new insights into the mechanisms and allowing the examination of conditions that are not accessible experimentally.     

Factors Affecting Work Ability in Day and Shift‐Working Nurses

Satisfactory work ability is sustained and promoted by good physical and mental health and by favorable working conditions. This study examined whether favorable and rewarding work‐related factors increased the work ability among European nurses. The study sample was drawn from the Nurses' Early Exit Study and consisted of 7,516 nursing staff from seven European countries working in state‐owned and private hospitals. In all, 10.8% were day, 4.2% were permanent night, 20.9% were shift without night shift, and 64.1% were shift workers with night shifts. Participants were administered a composite questionnaire at baseline (Time 0) and 1 yr later (Time 1). The Work Ability Index (WAI) at Time 1 was used as the outcome measure, while work schedule, sleep, rewards (esteem and career), satisfaction with pay, work involvement and motivation, and satisfaction with working hours at Time 0 were included as potential determinants of work ability. Univariate and multivariate analyses were conducted after adjusting for a number of confounders (i.e., country, age, sex, type of employment, family status, and other job opportunities in the same area). Work schedule was not related to Time 1 changes in WAI. Higher sleep quality and quantity and more favorable psychosocial factors significantly increased work ability levels. Higher sleep quality and quantity did not mediate the effect of work schedule on work ability. No relevant interaction effects on work ability were observed between work schedule and the other factors considered at Time 0. As a whole, sleep and satisfaction with working time were gradually reduced from day work to permanent night work. However, scores on work involvement, motivation, and satisfaction with pay and rewards were the highest in permanent night workers and the lowest in rotating shift workers that included night shifts.     

Effects of new ways of working on work hours and work location,health and job-related outcomes

ABSTRACT

New ways of working (NWW) is a type of work organization that is characterized by temporal and spatial flexibility, often combined with extensive use of information and communication technologies (ICT) and performance-based management. In a three-wave intervention study, we examined the effects of NWW on both the organization of work (changes in control over time and place of work; working hours and work location; and other key job characteristics), and on employees’ outcomes (work–nonwork balance; health and well-being; and job-related outcomes). We applied a quasi-experimental design within a large Dutch financial company (N = 2,912). We studied an intervention group (n = 2,391) and made comparisons with a reference group (n = 521). There were three study waves: (i) one/two months before, and (ii) 4 months and (iii) 10 months after implementation of NWW. Repeated measures analyses of covariance (involving 361 participants from the intervention group and 80 participants from the reference group) showed a large and significant shift from hours worked at the office to hours worked at home after implementation of NWW. Accordingly, commuting time was reduced. Employees remained working on week days and during day time. Psychosocial work-characteristics, work–nonwork balance, stress, fatigue, and job-related outcomes remained favourable and largely unaffected, but the health score in the intervention group decreased (medium effect). These findings suggest that the implementation of NWW does not necessarily lead to changes in psychosocial work characteristics, well-being or job-related outcomes.     

CHANGES IN WORKING TIME ARRANGEMENTS OVER TIME AS A CONSEQUENCE OF WORK-FAMILY CONFLICT

Existing longitudinal studies on the relationship between working time arrangements (WTA) and work-family conflict have mainly focused on the normal causal relationship, that is, the impact of WTA on work-family conflict over time. So far, however, the reversed relationship, that is, the effect of work-family conflict on adjustments in WTA over time, has hardly been studied. Because work-family conflict is highly prevalent in the working population, further insight in this reverse relationship is invaluable to gain insight into secondary selection processes. The aim of this study is to investigate whether work-family conflict is prospectively related to adjustments in work schedules, working hours, and overtime work, and to explore sex differences and different time lags in this relation. Data of the prospective Maastricht Cohort Study were used. To study the effect of work-family conflict on a change from shift- to day work over 32 months of follow-up, male three-shift (n?=?727), five-shift (n?=?932), and irregular-shift (n?=?451) workers were selected. To study effects of work-family conflict on reduction of working hours over 12 and 24 months of follow-up, respectively, only day workers (males and females) were selected, capturing 5809 full-time workers (≥36?h/wk) and 1387 part-time workers (<36?h/wk) at baseline. To examine effects of work-family conflict on refraining from overtime work over 12 months of follow-up, only day workers reporting frequent overtime work at baseline were selected (3145 full-time and 492 part-time workers). Cox regression analyses were performed with adjustments for age, educational level, and presence of a long-term illness. Work-family conflict was associated with a significantly increased risk of changing from shift- to day work over 32 months of follow-up in three-shift workers (relative risk [RR]?=?1.77, 95% confidence interval [CI] 1.19–2.63) but not in five-shift workers (RR?=?1.32, 95% CI 0.78–2.24) and irregular-shift workers (RR?=?0.81, 95% CI 0.50–1.31). Within day workers, work-family conflict among full-time workers was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up in women (RR?=?2.80, 95% CI 1.42–5.54) but not men (RR?=?1.34, 95% CI 0.81–2.22). In part-time workers, work-family conflict was associated with a significantly increased risk of reducing working hours during 1 yr of follow-up both in women (RR?=?1.99, 95% CI 1.04–3.82) and men (RR?=?4.03, 95% CI 1.28–12.68). Whereas the effects of work-family conflict on a reduction of working hours somewhat decreased among female full-time workers after 2 yr of follow-up (RR?=?2.13, 95% CI 1.24–3.66), among male full-time workers the effects increased and reached statistical significance (RR?=?1.53, 95% CI 1.05–2.21). Work-family conflict was not significantly associated with refraining from overtime work over 1 yr of follow-up. This study shows that work-family conflict has important consequences in terms of adjustments in work schedules and working hours over time, with considerable sex differences. The study thereby clearly illustrates secondary selection processes both in shift- and day workers, with significant implications for labor force participation, emphasizing the need for prevention of work-family conflict (Author correspondence: Nicole.Jansen@epid.unimaas.nl).     

The French 35-hour workweek: a wide-ranging social change

The reduction of the legal working week to 35 hours in France has generated wide-ranging 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.