Aging and Shift Work: A Complex Problem to Face

The baby boomer generation is well into the 50+ age bracket, making it one of the largest demographic age cohorts. Whereas this cohort would have previously considered retirement, the evidence suggests that it will remain in the workforce for a longer period in response to a number of social and economic drivers. Mandatory retirement has either been abolished or is under consideration. An increased and healthier life expectancy means that people may work longer for financial and/or psychological reasons. In addition, a global shortage of skilled labor will result in efforts to keep employees in the workplace for longer periods. These trends have a number of implications for working time. What are the health implications of an aging workforce? How do we sustain good work ability into the latter years? What do we know about aging and shift work? What actions are required in the workplace to assist aging workers? This paper is not a comprehensive review of the literature but serves to highlight the complexities in understanding the relationship between shift work and aging. We discuss aging and human function and, in particular, the impact of aging on the circadian system. In addition, we outline new policy directions in this area and raise several suggestions to assist the well‐being of aging workers.     

Shift Work,Safety, and Aging

It has long been recognized that older shift workers may have shorter and more disturbed day sleeps between successive night shifts than their younger colleagues. This has given rise to considerable concern over the safety of aging shift workers because of the increasing age of the work force and increases in retirement age. Because there have been no direct studies of the combined effects of shift work and age on safety, the present paper begins by reviewing the literature relating safety to features of shift systems. It then considers the general effect of age on occupational injury rates before examining existing evidence of the combined effects of shift work and age on performance capabilities. The results of the literature review indicate that when the a priori risk is constant, there is reasonably clear evidence that injury rates are higher at night, and that they increase over successive night shifts more rapidly than over successive day shifts. Further, although occupational injuries are less frequent in older workers, those that do occur tend to be more serious. Finally, there is some suggestive evidence from studies of objectively measured performance capabilities that older workers may be less able to both maintain their performance over the course of a night shift and cope with longer spans of successive night shifts. It is concluded that it seems possible, even though unproven as yet, that older workers may be at greater risk both to injury and accident on the night shift. There is a strong need for future epidemiological studies of the combined effects of shift work and age on injuries and accidents, and that these should attempt to separate the effects of age per se from those of generation.     

Shift work, safety, and aging

It has long been recognized that older shift workers may have shorter and more disturbed day sleeps between successive night shifts than their younger colleagues. This has given rise to considerable concern over the safety of aging shift workers because of the increasing age of the work force and increases in retirement age. Because there have been no direct studies of the combined effects of shift work and age on safety, the present paper begins by reviewing the literature relating safety to features of shift systems. It then considers the general effect of age on occupational injury rates before examining existing evidence of the combined effects of shift work and age on performance capabilities. The results of the literature review indicate that when the a priori risk is constant, there is reasonably clear evidence that injury rates are higher at night, and that they increase over successive night shifts more rapidly than over successive day shifts. Further, although occupational injuries are less frequent in older workers, those that do occur tend to be more serious. Finally, there is some suggestive evidence from studies of objectively measured performance capabilities that older workers may be less able to both maintain their performance over the course of a night shift and cope with longer spans of successive night shifts. It is concluded that it seems possible, even though unproven as yet, that older workers may be at greater risk both to injury and accident on the night shift. There is a strong need for future epidemiological studies of the combined effects of shift work and age on injuries and accidents, and that these should attempt to separate the effects of age per se from those of generation.     

Who is too old for shift work? Developing better criteria

Demographic and social trends in industrialized countries are expected to lead to increasing numbers of older shift workers, raising concerns about possible health and safety risks. For older night workers, the International Labour Organization has recommended options for transferring to day work or early retirement, but few States have adopted these measures. For commercial air transport pilots, the International Civil Aviation Organization has implemented a series of regulatory measures that could manage the risks associated with aging, including a mandatory retirement age, regular medical assessments for fitness to fly, and limits on the duration of duty and rest. Each of these approaches has strengths and weaknesses. The mandatory retirement age is effectively arbitrary, has been controversial, and was recently increased from 60 to 65 yrs for one member of a two-person cockpit crew. Medical assessments offer a more individualized approach, but to improve safety, they must address aspects of health and physical or mental function that affect work performance and safety outcomes. The traditional focus has been on cardiovascular risk factors, although cardiac incapacitation is not a cause of accidents in a two-person cockpit aircraft. On the other hand, while pilot fatigue is an acknowledged cause of accidents, there is currently no requirement to consider issues associated with fatigue or sleep problems in fitness-to-fly medical assessments. Older long-haul pilots show greater sleep fragmentation than their younger colleagues and those in the general population. Sleep becomes more fragmented with increasing age, but the functional significance of this remains unclear. Among younger adults, experimental sleep fragmentation leads to increased sleepiness and degradation of performance and mood. Greater sleep loss is reported by older long-haul pilots, as well as other older shift workers, compared to younger people working similar duty patterns. Experimental sleep restriction causes a degradation of performance and mood that is cumulative and dose-dependent. In addition, a recent large-scale flight simulation study indicates that the duration of sleep obtained by individual pilots is an independent predictor of crew performance in a two-person cockpit. Based on these considerations, we propose that fatigue and sleep-related issues should become a standard part of fitness-for-work medical assessments, particularly for older shift workers. A multi-layered approach is proposed, with a routine structured sleep history leading to referral to specialist sleep services where appropriate. Criteria for specialist referral and medical retirement should be related to the workplace risk represented by an older worker. Additional research is needed to develop and validate sleep-related criteria for assessing fitness for work. For example, a better understanding of the effects of sleep fragmentation on the waking function of older workers might lead to a fragmentation threshold for fitness for work. The potential negative effects of unemployment and early retirement also need to be taken into account when considering the options for managing the occupational health and safety needs of older shift workers.     

Who Is Too Old for Shift Work? Developing Better Criteria

Demographic and social trends in industrialized countries are expected to lead to increasing numbers of older shift workers, raising concerns about possible health and safety risks. For older night workers, the International Labour Organization has recommended options for transferring to day work or early retirement, but few States have adopted these measures. For commercial air transport pilots, the International Civil Aviation Organization has implemented a series of regulatory measures that could manage the risks associated with aging, including a mandatory retirement age, regular medical assessments for fitness to fly, and limits on the duration of duty and rest. Each of these approaches has strengths and weaknesses. The mandatory retirement age is effectively arbitrary, has been controversial, and was recently increased from 60 to 65 yrs for one member of a two‐person cockpit crew. Medical assessments offer a more individualized approach, but to improve safety, they must address aspects of health and physical or mental function that affect work performance and safety outcomes. The traditional focus has been on cardiovascular risk factors, although cardiac incapacitation is not a cause of accidents in a two‐person cockpit aircraft. On the other hand, while pilot fatigue is an acknowledged cause of accidents, there is currently no requirement to consider issues associated with fatigue or sleep problems in fitness‐to‐fly medical assessments. Older long‐haul pilots show greater sleep fragmentation than their younger colleagues and those in the general population. Sleep becomes more fragmented with increasing age, but the functional significance of this remains unclear. Among younger adults, experimental sleep fragmentation leads to increased sleepiness and degradation of performance and mood. Greater sleep loss is reported by older long‐haul pilots, as well as other older shift workers, compared to younger people working similar duty patterns. Experimental sleep restriction causes a degradation of performance and mood that is cumulative and dose‐dependent. In addition, a recent large‐scale flight simulation study indicates that the duration of sleep obtained by individual pilots is an independent predictor of crew performance in a two‐person cockpit. Based on these considerations, we propose that fatigue and sleep‐related issues should become a standard part of fitness‐for‐work medical assessments, particularly for older shift workers. A multi‐layered approach is proposed, with a routine structured sleep history leading to referral to specialist sleep services where appropriate. Criteria for specialist referral and medical retirement should be related to the workplace risk represented by an older worker. Additional research is needed to develop and validate sleep‐related criteria for assessing fitness for work. For example, a better understanding of the effects of sleep fragmentation on the waking function of older workers might lead to a fragmentation threshold for fitness for work. The potential negative effects of unemployment and early retirement also need to be taken into account when considering the options for managing the occupational health and safety needs of older shift workers.     

Langer leven, langer werken?De rol van gepercipieerde levensverwachting in het uittredeproces

Virtually all Western countries are seeking to bring retirement ages more in line with increases in longevity. The central question in this paper is whether individuals choose a retirement age that fits their life expectancy. This would be ideal from a public policy perspective. The present study aims to test empirically whether retirement planning varies with expectations of survival among a sample of older employees in the Netherlands. Two questions are addressed: (1) What are older employees' expectations of their remaining lifetime, and what factors influence this subjective life expectancy? (2) Are individuals who perceive longer life horizons (high subjective life expectancy) more inclined to retire later than people who expect to live shorter? Using data from a panel study on retirement behaviour in the Netherlands (N=1621 older employees aged 50-60), regression and survival models are estimated to examine the effect of subjective life expectancy on retirement planning and behaviour. The results indicate that subjective life expectancy is a factor that is taken into account in retirement decision making, at least as far as retirement intentions are concerned. Older employees with longer time horizons have a preference for later retirement. When it comes to actual behaviour, however, time horizon does not appear to play a role. The results suggest that particularly employees with a high perceived life expectancy and an intention to work longer do not succeed in carrying their intentions into effect.     

No “honeymoon phase”: whose health benefits from retirement and when

Does retirement lead to a short, transitory health boost, followed by a stable longer-run effect? The short-run effect has been hypothesized to be a kind of honeymoon effect, that is followed by a longer-run effect that may be either positive or negative. We examine the time path of the health effect of retirement and study effect heterogeneities between individuals along several dimensions. Moreover, we study a broad range of health outcomes, all in order to come to an understanding of the effect patterns that lie behind the diverse findings reported in previous research. For identification we use a fixed effects instrumental variable approach in which the normal and early retirement age thresholds serve as instruments. Using data for 10 countries from the Survey of Health, Retirement and Ageing in Europe (SHARE), we find that retiring both at the normal and early retirement eligibility ages significantly improves all the health aspects we consider. Other than hypothesized, results do not show a honeymoon phase-like transitory health boost. Instead, especially blue-collar workers go through an adjustment period after retiring, in which their health worsens. Afterwards, health stabilizes and improves, so that retirement has a health preserving effect in the longer run. This beneficial health effect of retirement occurs across all occupational groups, across a range of health outcomes, and for both sexes, though there are a number of heterogeneities between groups regarding which health outcomes are particularly affected.     

Support measures to improve night and shift work conditions in Thailand: a case study in a glass factory

The present study aimed to examine the working conditions of shift workers in a multinational enterprise in Thailand and to identify practical support measures for improvements. A multinational, glass-manufacturing factory employing 1,500 workers was selected as the research site. Three shift systems in three teams were adopted. A direct observation study and a fatigue feeling monitoring study were carried out to compare the differences between different shifts. A 10-day time-budget study was conducted for 30 shift workers to know their work and sleep patterns. The direct observation study identified safety and health risks during the night work periods. The risks included insufficient lighting, height gaps on the floor, excessive exposure to heat, inappropriate workstations, and sleepiness and fatigue feelings among shift workers. Working consecutive double shifts and overtime work was often seen. An advisory meeting was held based on the study findings to assist managers and workers in improving their working conditions. A follow-up visit six months later confirmed that the glass factory implemented several improvements to help night and shift workers. It was concluded that the direct observation methods associated with the time-budget study were helpful for identifying practical action points and strengthening workplace initiatives.     

Integrating evolutionary and molecular genetics of aging

Aging or senescence is an age-dependent decline in physiological function, demographically manifest as decreased survival and fecundity with increasing age. Since aging is disadvantageous it should not evolve by natural selection. So why do organisms age and die? In the 1940s and 1950s evolutionary geneticists resolved this paradox by positing that aging evolves because selection is inefficient at maintaining function late in life. By the 1980s and 1990s this evolutionary theory of aging had received firm empirical support, but little was known about the mechanisms of aging. Around the same time biologists began to apply the tools of molecular genetics to aging and successfully identified mutations that affect longevity. Today, the molecular genetics of aging is a burgeoning field, but progress in evolutionary genetics of aging has largely stalled. Here we argue that some of the most exciting and unresolved questions about aging require an integration of molecular and evolutionary approaches. Is aging a universal process? Why do species age at different rates? Are the mechanisms of aging conserved or lineage-specific? Are longevity genes identified in the laboratory under selection in natural populations? What is the genetic basis of plasticity in aging in response to environmental cues and is this plasticity adaptive? What are the mechanisms underlying trade-offs between early fitness traits and life span? To answer these questions evolutionary biologists must adopt the tools of molecular biology, while molecular biologists must put their experiments into an evolutionary framework. The time is ripe for a synthesis of molecular biogerontology and the evolutionary biology of aging.     

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.     

Shift-specific associations between age,chronotype and sleep duration

The objective of this study was to examine the association of age with chronotype and sleep duration in day workers and rotating shift workers, including night shift work. Between October 2012 and February 2015, a cross-sectional study was conducted in a German chemical company. Using the “Munich ChronoType Questionnaire” (MCTQ), data about sleep onset and sleep offset during workdays and work-free days were retrieved and the chronotype was computed during regular voluntary occupational health check-ups. Associations between age and chronotype, as well as sleep duration, were assessed using linear regression analyses. Potential effect modification by the working time system was examined. Within the study period, 4,040 employees (82.3% and 17.7% were engaged in day work and rotating shift work, respectively) completed the questionnaire. Study participants were on average 41.8 years old (Min = 18.0, Max = 65.0, SD = 10.2) and predominantly male (75.4%). Mean chronotype and overall sleep duration was 03:22 (SD = 54 min) and 7.2 h (SD = 1.0 h) respectively. Older age was associated with earlier chronotype and reduced overall sleep duration in both day workers and rotating shift workers (p < 0.001 for all models). Compared to day workers, employees whom engaged in rotating shift work were later chronotypes and had overall a longer sleep duration. With older age, the difference between day and rotating shift workers regarding chronotype increased, while the difference regarding overall sleep duration decreased (p_interaction<0.005 for both models). This finding could indicate that both changes in circadian physiology and exposure to certain work schedules contribute to the age-related changes. Older rotating shift workers, with early chronotypes may have issues with night shifts, while day work and morning shifts may be best compatible to earlier chronotypes. Differences in sleep timing across age groups, might indicate that the same work hours will affect shift workers differently, dependent on their age, suggesting that more flexible and chronotype-adapted work hours could provide useful; especially for older employees. Sleep education in the form of courses and health campaigns could be a way to raise awareness of the importance of a healthy sleep pattern. This could be achieved by learning strategies to better adjust individual sleep patterns to work hours.     

Comparisons of psychosomatic health and unhealthy behaviors between cleanroom workers in a 12-hour shift and those in an 8-hour shift

The General Health Questionnaire (GHQ12) and physical fitness tests were administered to 338 workers in clean rooms producing electronic parts in 12-h shifts. The results were compared to those in 95 workers in 8-h shifts and 284 daytime management, clerical and engineering workers. The 12-h shift workers complained of poor health, dissatisfaction with life and poor recuperation from fatigue more than the 8-h shift workers although the rates of complaints were highest in the daytime workers. The GHQ scores were similar in the two shift groups, and much better than those in the daytime workers. However, the 12-h shift workers showed significantly lower fitness levels than the 8-h shift workers, and the levels were even worse than the daytime workers who had higher mean age and BMI levels compared with the shift workers. The tendency to have sedentary freetime activities and larger alcohol and cigarette consumption were observed in the 12-h shift workers. The 12-h shift work may have contributed to the unhealthy behaviors resulting in lower physical fitness levels. Health promotion services at the workplace should devote greater attention to long-hour shift workers, together with devising the ways to improve working conditions and environments for reducing fatigue at work.     

Will Risks to Older Workers Change in the 21st Century?

Workers aged 65 and older face different risks than those in younger age groups. The occupational fatality rate for this group (13.6 per 100,000 workers) during 1980-1995 was almost three times greater than the rate for workers aged 16 to 64. This study projects the traumatic occupational fatality experience for the ten occupations with the largest number of occupational fatalities for workers 65 years and older. Although the occupational fatality rate for workers 65 years and older is projected to decrease from 12.5 in 1995 to 11.5 in year 2008, the number of occupational fatalities for this group is projected to increase from 459 in 1995 to 518 in year 2008. The overall proportion of occupational fatalities experienced by workers in the 65 years and older age group is expected to increase from 7% in 1995 to 10% in 2008. To assist in developing the most effective interventions, the five leading external causes of death associated with these fatalities were estimated for year 2008. With the aging of the American workforce, more research is needed in areas concerned with protecting older workers from injury.     

Linking stemness with colorectal cancer initiation,progression, and therapy

The discovery of cancer stem cells caused a paradigm shift in the concepts of origin and development of colorectal cancer. Several unresolved questions remain in this field though. Are colorectal cancer stem cells the cause or an effect of the disease? How do cancer stem cells assist in colorectal tumor dissemination to distant organs? What are the molecular or environmental factors affecting the roles of these cells in colorectal cancer? Through this review, we investigate the key findings until now and attempt to elucidate the origins, physical properties, microenvironmental niches, as well as the molecular signaling network that support the existence, self-renewal, plasticity, quiescence, and the overall maintenance of cancer stem cells in colorectal cancer. Increasing data show that the cancer stem cells play a crucial role not only in the establishment of the primary colorectal tumor but also in the distant spread of the disease. Hence, we will also look at the mechanisms adopted by cancer stem cells to influence the development of metastasis and evade therapeutic targeting and its role in the overall disease prognosis. Finally, we will illustrate the importance of understanding the biology of these cells to develop improved clinical strategies to tackle colorectal cancer.     

Physicians' adjustment to retirement.

We address the questions, How do physicians adjust to and enjoy their retirement? What factors contribute to the well-being of retired physicians? A 60-item questionnaire mailed to 238 retired physicians in Los Angeles County with a 41.6% response rate assessed health, standard of living, relationships, activities, emotional difficulties, and general enjoyment. Health often improved after retirement, as did relationships with spouses and children. Standard of living was comfortable or better for most. Retired physicians engage in a wide range of interests and activities. Emotional difficulties are minimal and considerably reduced after retirement. Most physicians enjoy the freedom and activities of retirement and are happy. Fears of boredom and deterioration are unfounded.     

Neoliberal eclipse: Donald Trump,corporate monopolism,and the changing face of work

At the core of his political rhetoric, Donald Trump speaks about work: the experience of laboring, the agonies of the labor market, and the future of employment. This article considers how the anthropology of work can contribute to an analysis of the political moment. Many commentators, including Trump himself, have interpreted a vote for Trump as an act of labor nostalgia, a gesture of yearning for an industrial past. Such commentary describes Trump voters by describing the jobs that many of them once did—manufacturing jobs. But what if, instead, we considered the jobs that many Trump voters now do, that is, service jobs? What if Trump’s discourse, with its themes of domination and submission, offers an incisive response to the intimacies of power as lived by restaurant workers and customer service representatives? Could the election come into focus as an uprising in the service sector? This article takes two steps. First, it engages with literature from sociology and economics in order to point towards a crucial transformation in the US workplace since the 2008 financial crisis: the ascendancy of monopolistic corporations that defy the neoliberal model. Second, the article explores new developments in the service sector by assessing the work experience of Uber drivers. Trump’s rhetoric can be interpreted as a response to the 2008 crisis and the novel modes of service work that the crisis made possible—including Uber. As it faces the political consequences of today’s toil, the anthropology of work gains a new research agenda.     

Age-related changes in photosynthesis of woody plants

Woody peoffnials do not appear to go through a defined senescence phase but do have predictable developmental stages. Reduced photosynthesis and stomatal conductance have been reported at all developmental transitions, although some studies have shown the opposite. What causes these changes and why do results differ among studies? Do these changes result from or cause changes in growth? What are the roles of genetics, size, changing conditions and cumulative environmental stress in aging trees? Definitive answers remain elusive but recent research is helping to clarify some of the processes associated with aging and to point the way for further study.     

Questions sur la remédiation cognitive dans les schizophrénies

What are the implications of an approach to schizophrenia using a cognitive remediation and what is the case for such an approach? What are its strengths and its weaknesses? More critically, can we find supporting evidence of its efficacy? Overall, what do we really know of the cognitive disorders associated with the schizophrenias? Opening on a review of the existing literature in order to investigate such questions, the paper develops a critical assessment of the issue.     

The Relationship between Sleep and Shift System, Age and Chronotype in Shift Workers

The purpose of this study was to investigate the effects of shift system, age, and chronotype on the sleep habits, sleepiness and catnaps of shift workers during night work. We administrated a Morningness-Eveningness Questionnaire and Life Habits Inventory to 561 male shift workers of three different shift systems in Korea. The mean scores on the Morningness-Eveningness Questionnaire clearly shifted toward the Morning type from the young to old groups. The waking and bedtimes during the day and evening shift were earlier for the older than for the younger groups, and these times were earlier across the Evening, Intermediate, to Morning type as well. Sleep length during the day shift was longer from the young to old, and it was shorter from the Evening, Intermediate, to Morning type. In the weekly rotation full-day 3-team 3-shift system and continuous full-day 3-team 3-shift system (which had earlier starting times for day shift) the sleep length of the younger workers was short. For the aged workers, sleep length during the night shift was short because they woke up early. In the weekly rotation full-day 2-team 2-shift system that had a short working interval, the reduction of sleep length during night shift was greater than that of the other shift systems. However, the scores on the Morningness-Eveningness Questionnaire showed a significantly negative correlation only in the bedtime during day shift among the sleep habit parameters for the independent variable by age. For the percentage of subjects that reported 'become sleepiness', the degree and time of sleepiness during the night shift were greater and earlier for the older than for the younger workers, and greater for the Morning than for the Evening type. The percentage of subjects who took a catnap during night shift, as well as the length of their catnap, were also higher and longer for the older groups, and higher and longer for the Morning type than for the Evening type. From these results, we surmised that the sleep habit parameters were influenced the age or shift systems rather than the chronotype. The sleep length during the night shift was shorter for the aged than for the young. In the shift systems that have a short working interval, the nocturnal was remarkably shorter for the young than the aged. The aged had not adapted their sleep for the night shift compared to the young, this suggested by the aged's strong complaint of sleepiness and by the fact that a larger percentage of aged subjects said they took catnaps during night shift compared to the younger workers.