Age and the subjective experience of shiftwork

The objective of this study was to examine age related effects of shiftwork albeit difficult to tease apart the natural effects of aging, and lifestyle or behaviour, or job done, over time and the shifts a person works. This is an issue of concern because the numbers of shiftworkers over 45 are increasing. Participants were 306 police officers who had worked a new rota for approximately 6 months. Three age groups were compared (1 = 20-32.9, 2 = 33-39.9, 3 = 40+) using a range of shiftwork-related measures and multivariate analysis of covariance (controlling for shiftwork experience and other individual differences). Younger officers tended to report significantly better attitudes towards their shiftwork, better adjustment to night-bound shifts, greater job satisfaction and organisational commitment, lower fatigue and longer sleep durations. Older shiftworkers reported significantly higher morningness and lower sleep need than the younger officers. This concurred with existing research that implicates such variables in the mechanism(s) involved in age-related tolerance to shiftwork. It was also evident that the older group tended to resort to greater caffeine intake on all shifts. The findings offer tentative support for the position that age can be linked to depleted shiftwork tolerance but the issue of establishing the relative impacts of aging, lifestyle, behaviour, work type and the rota worked remains to be a challenge.     

Sleepiness in a population of Italian shiftwork policemen

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.     

Effect of shiftwork on systemic markers of inflammation

Shiftwork is associated with an increased risk of cardiovascular diseases, but the possible role of inflammation in this relationship is not well known. We tested the hypothesis that shiftwork would be associated with higher levels of C-reactive protein (CRP) and increased leukocyte count. We analyzed the cross-sectional associations between work arrangements and low-grade inflammation in 1877 airline-company employees separately for men (n?=?1037) and women (n?=?840). The participants were classified into five categories according to their work schedule: day workers who have not worked in shifts (referent group), former shiftworkers, 2-shift workers, 3-shift workers, and in-flight workers. In models adjusted for age and recent infectious diseases, CRP levels were higher among male 3-shift workers (p = .002) and marginally higher in male 2-shift workers (p = .076). In addition, leukocyte count was higher in 2-shift (p = .005) and 3-shift (p = .021) working men. In women, CRP level was higher in 2-shift workers (p = .028), whereas leukocyte count was lower in flight workers (p = .005). Any separate adjustment additionally for smoking, education, alcohol consumption, physical activity, and obesity did not substantially affect the results of 2- and 3-shift work. In the fully adjusted model, only the association between 3-shift work and CRP in men (p = .021) and 2-shift work and leukocyte count in men (p = .020) and leukocyte count in 3-shift-working women (p = .044) were significant. Our results suggest that 2- and 3-shift work is associated with increased systemic inflammation and the relationship is relatively independent of the considered risk factors of cardiovascular disease.     

Adipokine levels are altered by shiftwork: a preliminary study

Shiftwork is often associated with metabolic diseases, and in the past few years, several cytokines have been postulated to contribute to various diseases, including insulin resistance. The aim of this study was to compare the concentrations of adiponectin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in samples of young adult men exposed to a fixed (i) night shift (n = 9), working from 22:00 to 06:00 h; (ii) early morning shift (n = 6), working from 06:00 to 14:00 h; and (iii) day shift (n = 7), working from 08:00 to 17:00 h. The fixed night-shift and early-morning-shift samples were considered collectively as a shiftworker group given their work times. Blood samples were collected during the regular working day at 4-h intervals over the course of 24 h, thus totaling six samples. Morphological and physical activity parameters did not differ between the three groups. Total energy intake was lowest on the early morning shifts (p 相似文献   

Effects of supervisor support and coping on shiftwork tolerance

This study examines the effects of supervisor support and coping on work/non-work conflict and health in shiftwork. It describes a model of shiftwork tolerance that is tested on samples from two populations of shiftworkers. The samples--of nurses and ambulance workers--differed by occupation, gender and shift schedule. Quantitative (survey questionnaire) and qualitative methods (in-depth interviews) were used to triangulate results and to yield richer data on psychosocial variables. Structural equation modelling, using EQS, was used to describe the common path relationships observed within both samples of shiftworkers. The results demonstrated important relationships between social support from supervisors, coping strategies, work/non-work conflict and symptoms that transferred robustly between the two populations of shiftworkers.     

Predicting shiftwork-related outcomes: shiftwork locus of control and circadian type

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.     

The effect of shiftwork on driving to and from work

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.     

Physical fitness and other individual factors relating to the shiftwork tolerance of women

Maximal oxygen consumption (VO2max), muscle strength (MS) and physical activity were compared to age, shiftwork experience, morningness, personality traits and social factors intervening in the shiftwork tolerance of 128 women. The subjects were nurses and nursing aids working irregular shifts in a hospital. Neuroticism was the most powerful negative factor connected to higher fatigue and various symptoms of the subjects. High VO2max and good MS were, on the other hand, the most important positive factors connected to lower fatigue and musculoskeletal symptoms and better sleep quality of the subjects. In different shifts, fatigue, sleep length and quality were influenced most by morningness. It is concluded that physical fitness is an important individual factor explaining the variations of shiftwork tolerance in women.     

Unaltered instrumental learning and attenuated body-weight gain in rats during non-rotating simulated shiftwork

Exposure to shiftwork has been associated with multiple health disorders and cognitive impairments in humans. We tested if we could replicate metabolic and cognitive consequences of shiftwork, as reported in humans, in a rat model comparable to 5 wks of non-rotating night shifts. The following hypotheses were addressed: (i) shiftwork enhances body-weight gain, which would indicate metabolic effects; and (ii) shiftwork negatively affects learning of a simple goal-directed behavior, i.e., the association of lever pressing with food reward (instrumental learning), which would indicate cognitive effects. We used a novel method of forced locomotion to model work during the animals' normal resting period. We first show that Wistar rats, indeed, are active throughout a shiftwork protocol. In contrast with previous findings, the shiftwork protocol attenuated the normal weight gain to 76 ± 8 g in 5 wks as compared to 123 ± 15 g in the control group. The discrepancy with previous work may be explained by the concurrent observation that with our shiftwork protocol rats did not adjust their between-work circadian activity pattern. They maintained a normal level of activity during the "off-work" periods. In the control experiment, rats were kept active during the dark period, normally dominated by activity. This demonstrated that forced activity, per se, did not affect body-weight gain (mean ± SEM: 85 ± 11 g over 5 wks as compared to 84 ± 11 g in the control group). Rats were trained on an instrumental learning paradigm during the fifth week of the protocol. All groups showed equivalent increases in lever pressing from the first (3.8 ± .7) to the sixth (21.3 ± 2.4) session, and needed a similar amount of sessions (5.1 ± .3) to reach a learning criterion (≥ 27 out of 30 lever presses). These results suggest that while on prolonged non-rotating shiftwork, not fully reversing the circadian rhythm might actually be beneficial to prevent body-weight gain and cognitive impairments.     

Effects of lifetime exposure to shiftwork on fitness for duty in police officers

Aging and demographic changes in Europe and other global economies have led to a discussion about postponing the legal retirement age; however, health and safety consequences for the workforce have not yet been examined. Thus, the aim of this study was to investigate the effects of lifetime exposure to shiftwork on health impairments and fitness for duty. Two samples of the police force from one of the states of the Federal Republic of Germany were used. One sample was collected in 2008-2009 with a self-administered Internet questionnaire (n = 705); the other sample was derived from employment records provided by the police force of the same federal state for the years 2002-2009 (n = 2460). Both samples contained information about the number of years worked in shiftwork across the entire working life and impairments to fitness for duty assessed by occupational physicians. Thus, the number of years of shiftwork until the diagnosis of the first reduction in fitness for duty could be calculated. Survival analyses were performed to estimate the risk (hazard rate) for experiencing a reduction in fitness for duty across lifetime exposure to shiftwork in years, controlling for age, sex, work type, and police district. Hazard estimates were compared across both samples to cross-validate the results. The findings indicated an increase in the risk of reduced fitness for duty with increasing number of years in shiftwork during the working life in both samples. The hazard rates followed an exponential trend, indicating a rapid increase in health impairments in particular beyond 20 yrs of shiftwork. These findings were consistent in both samples, collected with different methods and over different time periods, thus indicating high validity. Therefore, occupational stress factors, such as exposure to shiftwork, need to be taken into account when discussing the postponement of the legal retirement age.     

Association of shiftwork and leukocytes among national health and nutrition examination survey respondents

Shift workers may experience disrupted sleep-wake or circadian cycles which, in turn, may lead to major health problems such as hypertension, obesity, and diabetes. Research indicates that shift workers have increased levels of leukocytes. Data from the National Health and Nutrition Examination Survey (2005–2010) examined the relationship between self-reported current shiftwork and leukocytes with adjustment for important confounders. Using linear regression, we found no association between shiftwork and leukocyte counts. Those not working had elevated levels compared to day workers but values in both groups were still within normal ranges. Additional research is needed to fully understand how shiftwork influences changes in leukocyte counts.