Current Shift Work Research Articles

Shiftwork and Prostate-Specific Antigen in the National Health and Nutrition Examination Survey

Shiftwork has been implicated as a risk factor for prostate cancer. Results from prior studies have been mixed but generally support an association between circadian disruption and prostate cancer. Our aim was to investigate the relationship between shiftwork and prostate-specific antigen (PSA) test obtained as part of the National Health and Nutrition Examination Survey (NHANES) study. We combined three NHANES surveys (2005-2010) to obtain current work schedule among employed men aged 40 to 65 years with no prior history of cancer (except nonmelanoma skin cancer). Men who reported working regular night shifts or rotating shifts were considered shiftworkers. We obtained the total and percentage free PSA test results for these men and dichotomized total PSA into less than 4.0 ng/mL or 4.0 ng/mL or greater and total PSA of 4.0 ng/mL or greater combined with percentage free PSA less than or equal to 25%. Using multivariable logistic regression models, we compared PSA level among current shiftworkers and nonshiftworkers. All statistical tests were two-sided. We found a statistically significant, age-adjusted association between current shiftwork and elevated PSA at the 4.0 ng/mL or greater level (odds ratio = 2.48, 95% confidence interval [CI] = 1.08 to 5.70; P = .03). The confounder-adjusted odds ratio was 2.62 (95% CI = 1.16 to 5.95; P = .02). The confounder-adjusted odds ratio for those with total PSA of 4.0 ng/mL or greater and free PSA less than or equal to 25% was 3.13 (95% CI = 1.38 to 7.09; P = .01). We observed a strong positive association with shiftwork and elevated PSA level. Our data support the notion that sleep or circadian disruption is associated with elevated PSA, indicating that shiftworking men likely have an increased risk of developing prostate cancer.

Helping women but hurting ourselves? Neck and upper back musculoskeletal symptoms in a cohort of Australian Midwives

ObjectiveTo determine the prevalence of neck and upper back musculoskeletal symptoms in a group of Australian midwives and explore individual characteristics and workplace exposures associated with these symptoms. Designcross-sectional, using data from the Nurses and Midwives e-Cohort Study, a longitudinal, electronic survey of midwives and nurses in Australia, New Zealand and the United Kingdom. Settingdata were collected via an online survey in 2006–2008. Participantsqualified Australian midwives aged 23–70 years. Measurements and findingsWe undertook descriptive analysis of the sample, calculated prevalence and examined associations between individual and workplace variables and neck and upper back musculoskeletal symptoms. Variables achieving p<0.1 in bivariate analysis were entered simultaneously into logistic regression models. Overall prevalence rates were 48.8% for neck and 28.2% for upper back musculoskeletal symptoms; work-related prevalence was 40.8% (neck) and 24.5% (upper back), comparable to reported rates among nurses and physicians. Presence of symptoms in the adjacent area was associated with greater than a fourfold increased risk for neck and upper back symptoms. Participants with care responsibility for an adult dependent were 36% more likely to report neck symptoms. Current shift work and total physical activity were associated with decreased likelihood of neck and upper back symptoms, respectively. Psychological job demands were only weakly associated with upper back symptoms, possibly because the survey tool could not capture a sufficiently broad range of psychosocial exposures to present a complete picture. A striking finding was that work in awkward postures conferred an increased risk of 35% for neck and nearly 50% for upper back symptoms. Key conclusionsneck and upper back musculoskeletal symptoms were prevalent in this sample. Both individual and workplace factors were significantly associated with neck and/or upper back symptoms. Psychological job demands and work in awkward postures are potentially modifiable exposures that deserve further examination. Implications for practicemidwives who are or may become carers for adult dependents should be aware of a possible increased risk for neck symptoms. It may be prudent for midwives and those who employ/supervise them to monitor and, where possible, jointly develop strategies to mitigate psychological job demands. The potential hazard posed by work in awkward postures warrants consideration of how midwives may minimize time spent working in these postures.

The relationship between current and former shift work and the metabolic syndrome

The occurrence of possible health hazards among former shift workers is not well-known. We studied associations of former and current shift work with the metabolic syndrome (MetS). Participants were 1811 full-time employees of a large airline company (1009 men). Working times were categorized into five groups: day worker [N=297 (the reference group)], former shift worker (N=341), 2-shift worker (N=418), night-shift worker (N=283), and in-flight worker (N=472). MetS was measured by the International Diabetes Federation (IDF) criteria and the National Institute of Health Adult Treatment Panel III (NCEP) guideline. The prevalence of the syndrome in the study population was 28.5% and 20.8%, respectively. Among male former shift workers, MetS was more prevalent compared to male day workers [IDF: age-adjusted odds ratio (OR) 2.13, 95% confidence interval (95% CI) 1.35-3.37; NCEP: OR 1.83, 95% CI 1.13-2.96]. Associations did not change after additional adjustments for education, smoking, physical activity, alcohol consumption, and insomnia symptoms (IDF: OR 2.00, 95% CI 1.26-3.19; NCEP: 1.67, 95% CI 1.02-2.72). Male 2-shift workers also had an elevated risk of IDF-defined MetS (OR 1.64, 95% CI 1.06-2.55) but the association weakened in the fully adjusted analyses (OR 1.48, 95% CI 0.93-2.24). Prevalence of the MetS was marginally significantly higher among night-shift work (IDF: OR 1.51, 95% CI 0.95-2.34) and was attenuated further with additional adjustments (OR 1.37, 95% CI 0.84-2.22). Among women, no significant differences in prevalence of the MetS between day work and shift work were observed. Findings of the cross-sectional study suggest that MetS diagnosed by standardized criteria is more prevalent among former male shift workers than current day workers who have never worked in shifts.

025 Evaluation of the Pharma-Smart model PS-2000 community-based automated blood pressure measuring device

recruited from 2 hospital sites in Southeastern Ontario. Data were collected through anthropometric measurement, serum sampling and self-report. Metabolic syndrome (MS) was classified in accordance with the recent AHA guidelines; specifically the prevalence of at least 3 of the following indicators: waist circumference (WC) 80 cm; hypertension (systolic BP 130 or diastolic BP 85 or treatment; elevated triglycerides 150 mg/dL or treatment; reduced HDL cholesterol 50 mg/dL or treatment and elevated fasting blood glucose (FBG) 100 mg/DL. RESULTS: The overall prevalence of MS was 16.7%; elevated WC (60.2%), hypertension (37.4%); elevated FBG (19.3%), reduced HDL (14.8%) and elevated triglycerides (10.0%). MS was significantly associated with increased age 45 years, menopausal status, shift work history of 6 years and currently working either 12 hour shifts or rotational shifts. The prevalence of MS increased with shift workhistory: 6years,7.9%(n 3),6-15years,18.4%(n 7)and 15 years, 73.7% (n 28). Adjusting for age, in multivariate analysis the risk of MS was only associated with current shift work status (OR 2.3 95% CI, 1.0, 4.9) and not shift work history of 10 years. CONCLUSIONS: Women who are currently working rotational and/or extended hour shifts with a history of shift work 10 years seem to be at increased cardiovascular risk. Given the prevalence of cardiovascular risk indicators, and in particular abdominal obesity and the increasing age of the female hospital workforce supports the need for examination of workplace policy for middle and older aged female hospital employees. Canadian Institutes of Health Research

Rethinking shiftwork: mid‐life nurses making it work!

Many current analyses of shiftwork neglect nurses' own voices when describing the dis/advantages of a shiftworking lifestyle. This paper reports the findings of a critical re-analysis of two studies conducted with female mid-life Australian nurses to explore the contention that the 'problem-centred' focus of current shiftwork research does not effectively address the 'real' issue for mid-life nurses, that is, how to develop and maintain shiftwork tolerance. Participants used shiftwork to: (i) manage, navigate and negotiate various aspects of their nursing work and the workplace itself; (ii) facilitate more manageable work/life negotiations; and (iii) self-identify opportunities to engage in their own self-care (body work and mind work). The findings thus went beyond simply exposing what nursing bodies do in time and space by bringing to the fore discussions of 'time-body' relationships, the embodiment of time and nurses re/configuration of that time demonstrating that the frequently unacknowledged positive aspects of shiftwork, when centred in discussions, give voice to other ways to think about shiftwork and a shiftworking lifestyle. Thus, our contention is that the 'problem-centred' focus of current shiftwork debates does little to address the 'real' issue for shiftworking mid-life female nurses - the development and maintenance of shiftwork tolerance.

Fatigue in Pilots of Remotely Piloted Aircraft Before and After Shift Work Adjustment

Remotely piloted aircraft (RPA) with long endurance allow near-continuous operations, necessitating the implementation of shift work for crewmembers to provide the necessary manning of ground control stations. Shift work has a well-known association with fatigue, degraded work performance, and an increased risk for errors and accidents. This study presents the results of a follow-up survey of a particular population of shift-working RPA crewmembers 1 yr after modification of their shift work schedule. A cross-sectional survey of 66 RPA crewmembers was conducted using a collection of validated fatigue scales. This data was compared to survey data collected a year prior from the same population and from a reference group of non-shift-working aircrew. Shift system features and individual and situational differences associated with fatigue were explored. Additionally, several alternative types of shift schedules were assessed through modeling and simulation. The study found no significant reduction in reported fatigue despite prior modifications to the shift work schedule to increase opportunities for recovery. Months shift working, sleep quality, and disturbances in family and social activities were associated with overall fatigue scores. Approximately half of those surveyed met criteria for occupationally significant fatigue. Months shift working, use of on-duty napping, and fatigue scores were predictive of those with occupationally significant fatigue. Modeling of feasible variants of the current shift work schedule failed to reveal a significantly improved alternative schedule. Collectively, the results demonstrate a persistent problem with chronic fatigue in this study population, likely reflective of continued inadequate opportunities for recovery and restorative sleep.

Epidemiology of Uriniary Melatonin in Women and Its Relation to Other Hormones and Night Work

Light exposure during night work suppresses melatonin production, and night work has been associated with an increased cancer risk. There is little information, however, about the interrelationships of night work, urinary melatonin levels, and levels of plasma steroid hormones in women.We examined the reproducibility of morning urinary measurements of 6-sulfatoxymelatonin over a 3-year period in 80 premenopausal women. We assessed correlations between average urinary melatonin and plasma steroid hormone levels and evaluated potential associations between night work and hormone levels, using current and long-term shift work information from two large, prospective cohorts, the Nurses' Health Study cohorts.The intraclass correlation for creatinine-adjusted 6-sulfatoxymelatonin was 0.72 (95% confidence interval, 0.65, 0.82). We found significantly increased levels of estradiol after longer durations of night work (geometric mean levels of estradiol, 8.8 pg/mL for women who never worked night shifts versus 10.1 pg/mL for women who worked 15 or more years of night shifts; P for trend = 0.03). We observed a significant inverse association between increasing number of nights worked within the 2 weeks preceding urine collection and urinary melatonin levels (r = -0.30, P = 0.008), but no association of recent night work with estradiol (r = 0.10, P = 0.41).A single morning urinary melatonin measurement is a reasonable marker for long-term melatonin levels among premenopausal women. Women who work on rotating night shifts seem to experience changes in hormone levels that may be associated with the increased cancer risk observed among night-shift workers.

Epidemiology of Urinary Melatonin in Women and Its Relation to Other Hormones and Night Work

Abstract Objective: Light exposure during night work suppresses melatonin production, and night work has been associated with an increased cancer risk. There is little information, however, about the interrelationships of night work, urinary melatonin levels, and levels of plasma steroid hormones in women. Method: We examined the reproducibility of morning urinary measurements of 6-sulfatoxymelatonin over a 3-year period in 80 premenopausal women. We assessed correlations between average urinary melatonin and plasma steroid hormone levels and evaluated potential associations between night work and hormone levels, using current and long-term shift work information from two large, prospective cohorts, the Nurses' Health Study cohorts. Results: The intraclass correlation for creatinine-adjusted 6-sulfatoxymelatonin was 0.72 (95% confidence interval, 0.65, 0.82). We found significantly increased levels of estradiol after longer durations of night work (geometric mean levels of estradiol, 8.8 pg/mL for women who never worked night shifts versus 10.1 pg/mL for women who worked 15 or more years of night shifts; P for trend = 0.03). We observed a significant inverse association between increasing number of nights worked within the 2 weeks preceding urine collection and urinary melatonin levels (r = −0.30, P = 0.008), but no association of recent night work with estradiol (r = 0.10, P = 0.41). Conclusion: A single morning urinary melatonin measurement is a reasonable marker for long-term melatonin levels among premenopausal women. Women who work on rotating night shifts seem to experience changes in hormone levels that may be associated with the increased cancer risk observed among night-shift workers.

Managing Shiftwork

As our culture increasingly depends on round-the-clock operations to provide necessary services and efficiently utilize productive capacities, more and more people are required to work shiftwork. Shiftwork, as experienced in this country, normally includes work during hours of darkness and work on weekends. Often, this round-the-clock coverage requires workers to “rotate” through three shifts (day, afternoon, and night), or to work a steady run of afternoon or night shifts. Previous research has linked shiftwork with disruptions of family life, health, sleep, safety, and productivity, in a variety of work situations. In addition, a poorly designed work schedule can adversely affect job satisfaction, employee turnover, and absenteeism. Given these facts, managers need to be made more aware of these often hidden challenges facing them and their workers. The way to meet these challenges is with research, education, and implementation of improved methods of scheduling and handling the management of shiftworkers. Such experimental improvements have already paid benefits both on and off the job for workers in some continuous operations. The successful management of shiftwork can involve many of the following approaches: 1) selecting workers who are biologically and psychologically adept at handling night work and/or changes in schedules, 2) selecting out potential shiftworkers who have medical predispositions toward illness on shiftwork schedules, 3) training workers and their families on how to cope with shiftwork, especially in the areas of family life, stress, sleep, and nutrition, 4) analyzing and matching the site-dependent operational, biological, and social requirements to an appropriate shiftwork schedule, and 5) surveying the workforce periodically and studying safety, productivity, and absence records to ascertain problems with (and possible modifications to) the current shiftwork schedule. It is important to note that the above list encompasses many disciplines and approaches to improving the status quo of shiftwork. This multi-faceted nature can best be termed a “human factors” approach, which necessarily should recognize all the components in this complex sociological-biological-technological system. It is hoped that human factors specialists will lend their considerable broad-based talents to solving shiftwork problems in the decades to come. The four papers in this session represent the major ways human resource managers can improve the work life of shiftworkers. The first report, by Dr. Charles A. Czeisler, describes in detail how shiftwork schedules can be designed for maximum biocompatibility, based on an actual intervention at a selected work site. The second paper, by Dr. Marty Klein, reports the comparative analysis of 8-hour versus 12-hour shifts in a case study of the electric power industry. This topic is especially appropriate, given the current popularity of compressed workweeks among many industrial workers. The third presentation, by Ms. Janie O'Connor, illustrates the design and utilization of a shiftworker training program to enhance the coping skills of shiftworkers and their families. In addition, the results of a public health intervention study of shiftworkers in the paper and mining industries will be presented. Finally, the fourth paper, by Dr. Susan Koen, discusses the critical role of organizational development in creating a management culture best capable of running 24-hour organizations. Each of these contributions represents a blend of theory, research, and actual practice in solving parts of the puzzle on how to manage shiftwork.