Distribution of rest days in 12 hour shift systems: impacts on health, wellbeing, and on shift alertness

Rostering in Air Traffic Control: A Narrative Review

Most Air Traffic Controllers (ATCOs) must cover uninterrupted work shifts for 24 h a day, seven days a week. The proper planning of a shift schedule requires consideration of at least three elements: the specific characteristics of the controller task, the physiological needs of the operator, and the definition of rest periods within rostering. We reviewed the literature for providing comprehensive guidance on the main requirements for the construction of a shift schedule for ATCOs. Our considerations are organized according to a rationale reflecting the most important criteria for the construction of the schedule: namely, the organization of rest periods conceptualized as intervals between cycles of shifts, intervals between individual shifts, and breaks within the shift. The suggested parameters could be used to construct shift schedules within a variation margin that depends on individual contexts of application.

Stress among Emergency Health Care Workers on Nuclear or Radiation Disaster: A Preliminary State Survey

BACKGROUND

The nuclear or radiation disaster risk within the French Auvergne-Rhone-Alpes state is low (but not absent) due to its proximity to four Nuclear Power Generation Centers and two regional cancer control centers. This study aims to compare subjective stress ratings for emergency health care workers regarding nuclear and radiation disasters between two locations: at work versus at home.

MATERIALS AND METHODS

We distributed an anonymous online questionnaire via RedCap^® to all emergency health care workers who could be involved in patient care after a nuclear or radiation disaster. It comprised 18 questions divided into three parts-theoretical knowledge and practical assessment, stress assessment, and sociodemographic criteria.

RESULTS

We analyzed 107 responses. There was a significant 11-point increase in stress levels between work and home regarding nuclear or radiation disaster risks (p = 0.01). Less than 25% of emergency health care workers surveyed benefited from annual training.

CONCLUSION

The stress levels of emergency health care workers regarding nuclear or radiation disaster were higher at work than at home and increased without annual training. It is important to increase knowledge about these protocols and to mandate yearly training for all workers potentially involved in these disasters.

The 12-hour shift: radiographers' perspectives and its applicability during a pandemic

Introduction

Traditionally, shift work for radiographers at our institution comprised of three shift patterns – morning (8am-2pm), afternoon (2pm–9pm) and night (9pm-8am). However, when COVID-19 was first detected in Singapore in January 2020, the 12-h shift was introduced for better team segregation and deployment to meet the service needs of the Emergency Department. The 12-h shift consisted of the day (9am-9pm) and night (9pm-9am) shifts. While the 12-h shift is common to nursing practices, it is new to the radiography profession within the study centre. This study explores the radiographers' perspectives of the new shift and the impact of shift patterns on radiographers' wellness and work performance compared to the original three shift patterns.

Methods

A mixed-methods design study was adopted for this single-centre evaluation. An anonymous online questionnaire was administered to radiographers who had experienced both shift types. Additionally, the number of radiographers who had taken sick leave, and images rejected and accepted from the X-ray consoles were retrospectively collected to measure the impact of the new shift.

Results

Radiographers experienced fatigue and appreciated the longer rest days associated with the 12-h shift. Additionally, the sick leave rates and image reject counts were more favourable with the 12-h shift pattern.

Conclusion

The findings indicate that the extended shift hours are effective during a pandemic but may result in radiographer burnout during a prolonged outbreak.

Implications for practice

Studying these variables will provide an effective starting point in understanding the efficacy and applicability of a 12-h shift system during pandemic periods.

Working time limits at sea, a hundred-year construction

In a view to protect workers from extended work periods as well as to comply with the Versailles Peace Treaty requirements, the International Labour Organization (ILO) regulated hours of work from 1919 using '8-hour workday and 48-h workweek' as yardsticks. However, a historical perspective demonstrates the ILO's difficulties in integrating such standards for sea workers. From 1920 to 1958, the ILO endeavoured to anchor the 8-hour workday principle in maritime conventions on working time and to ensure compliance by quantifying manning levels. Facing sectoral opposition and the obstacle of the minimum tonnage requirement, none of the conventions adopted during the first period entered into force. A second regulatory wave (1995-2007) initiated by the International Maritime Organization (IMO) orientated working time towards fatigue management and adopted the 14-hour workday. Absorbed by the ILO from 1996, this threshold facilitated the implementation of working time standards for sea workers. The existence of autonomous maritime governance at the ILO and the IMO complemented by the incorporation of the tonnage clause in maritime convention allowed the acceptance of the 14-hour workday system in spite of breaching the universal principles established a century ago. The departure between maritime and land standards show that sectoral interests prevail over labour rights. More decisively, current standards detached labour rights from workers' human nature and attached them directly to sectoral interests.

Subjective and objective assessments after a change from a 4-crew, 12-h shift to a 3-crew, 12-h shift schedule: an observational study

PURPOSE

To clarify the subjective and objective impacts of a change in a 12-h shift schedule, involving a reduction in the number of crews, on workers at an electronic parts production company.

METHODS

Forty-two workers participated in this study. Subjective indicators (e.g. questionnaires) and objective indicators [e.g., psychomotor vigilance task (PVT)], as well as an activity monitor-based sleep assessment, were measured during a > 1-year period that encompassed the shift schedule change. The study outcome was a comparison of work-related injury rates measured 1 year before and after the change in shift schedule.

RESULTS

After the shift schedule change, questionnaire scores regarding work-related burdens and PVT performance parameters, including mean response time and number of lapses, increased significantly. However, we also observed divergences in the trends of the subjective and objective measures 1 year after the change. Despite these variations in both types of measures, we observed no significant differences in work-related injury rates measured before and after the shift schedule change.

CONCLUSION

This study revealed that a reduction in the number of crews in a 12-h shift schedule has a negative impact on the subjective and objective indicator after the change in shift schedule; only indicators of alertness did not recover at 1 year after the change. Assessments of the workers' performances and the regular implementation of health and safety programs for more than 1 year are needed to maintain workers' health after the change in shift schedule.

Cognitive functions of shift workers: paramedics and firefighters - an electroencephalography study

Introduction. Working shifts has a negative impact on employee health and cognitive efficiency. The purpose of this study was to investigate the impact of shift work on cognitive functions - attention and working memory - using both behavioural and electrophysiological measures. Methods. The study was carried out on a group of 34 shift employees (18 paramedics, 16 firefighters) and on 17 day workers. Participants performed the attention network test and the N-back task with two conditions (1-back, 2-back) while the electroencephalography signal was recorded. Results. Observations included a higher amplitude of the P200 potential in paramedics (compared to the control group), a higher amplitude of the P300 potential after work than on a day off and the lowest increase in power in the θ band after the night shift. In firefighters, lower α desynchronization and lower synchronization in the α/β band were observed after a 24-h shift. Paramedics and firefighters had longer reaction times (N-back task). Conclusions. The results suggest that paramedics experience problems with sustained attention. Paramedics process visual stimuli in a different way; after a night shift, performing the tasks required more engagement of cognitive resources. For firefighters, a decrease in visual attention functions and cognitive inhibition was observed.

Are long nursing shifts on hospital wards associated with sickness absence? A longitudinal retrospective observational study

Objective

To investigate whether working 12 hr shifts is associated with increased sickness absence among registered nurses and health care assistants.

Background

Previous studies reported negative impacts on nurses’ 12 hr shifts; however, these studies used cross‐sectional techniques and subjective nurse‐reported data.

Methods

A retrospective longitudinal study using routinely collected data across 32 general inpatient wards at an acute hospital in England. We used generalized linear mixed models to explore the association between shift patterns and the subsequent occurrence of short (<7 days) or long‐term (≥7 days) sickness absence.

Results

We analysed 601,282 shifts and 8,090 distinct episodes of sickness absence. When more than 75% of shifts worked in the past 7 days were 12 hr in length, the odds of both a short‐term (adjusted odds ratio = 1.28; 95% confidence index: 1.18–1.39) and long‐term sickness episode (adjusted odds ratio = 1.22; 95% confidence index: 1.08–1.37) were increased compared with working none.

Conclusion

Working long shifts on hospital wards is associated with a higher risk of sickness absence for registered nurses and health care assistants.

Implications for Nursing Management

The higher sickness absence rates associated with long shifts could result in additional costs or loss of productivity for hospitals. The routine implementation of long shifts should be avoided.

[Seven hour shifts versus 12 hours in intensive nursing care: going against the tide]

Working in shifts has an impact on the well being of health care professionals, affecting their quality of life. The main objective of this study is to describe the consequences of 12hours work shifts versus 7hours for nursing professionals working in intensive care units. A cost-sectional, descriptive study was conducted in two tertiary hospitals of Barcelona, these being the Hospital Clínico and Hospital Vall d'Hebron (of 7hour and 12hour shifts, respectively). The data was collected through a questionnaire having 29 closed questions that was anonymous and self-administered. The questionnaire was based on two scales: Standard Shiftwork Index and Shiftwork. locus of control. Data was processed through SPSS V.18.0. The target population consisted of 85 people, for whom 52 surveys were valid: 22 in Hospital Clínico of Barcelona and 30 in Hospital Vall d'Hebron. Professionals working a 12-hour shift express higher levels of work and family conciliation, especially in the case of leisure time to enjoy (×2: 10.635 p=0.031) and family-friends time dedication as well as lower levels of perceived fatigue. No differences were found between type of shift and ease of development of professional work, even though the 12-hour shift has higher levels.

Sleep and circadian rhythms in mining operators: limited evidence of adaptation to night shifts

Cumulative sleep deprivation is often associated with work patterns involving night shift or early morning shifts. Adaptation of the circadian system to the shift pattern is reported to promote improved duration and quality of sleep and a concurrent improvement in performance. The current study followed twenty-nine operators at a live-in mining operation working to a seven-day, seven-night shift pattern who collected saliva samples for melatonin measurement, recorded sleep using activity monitors and diaries, and underwent performance testing (psychomotor vigilance task) for one complete roster cycle. The time of onset of melatonin secretion changed significantly (P=0.022) across the week of both Day and Night shifts (2104 h ± 16 min versus 2130 h ± 16 min, respectively), but the small magnitude of the change indicates a lack of true circadian rhythm adaptation to the lifestyle. Total sleep time was longer following the seventh Day shift (associated with a period of 24 h off prior to the commencement of Night shifts). There were no other changes in total sleep time. Further, there were no improvements in sleep onset latency or sleep efficiency on Day or Night shifts. However, reaction times recorded at the end of the shifts slowed across the seven Day and seven Night shifts indicative of impairments in psychomotor performance (F(6,168)=6.087, P<0.001). The results suggest that previous reports of adaptation to consecutive night shifts cannot necessarily be applied to onshore or Australian environments. Adaptation is dependent on factors such as light exposure, environmental conditions, shift parameters such as wake-up, work start and work end times and individual characteristics.

The link between fatigue and safety

The objective of this review was to examine the evidence for the link between fatigue and safety, especially in transport and occupational settings. For the purposes of this review fatigue was defined as 'a biological drive for recuperative rest'. The review examined the relationship between three major causes of fatigue - sleep homeostasis factors, circadian influences and nature of task effects - and safety outcomes, first looking at accidents and injury and then at adverse effects on performance. The review demonstrated clear evidence for sleep homeostatic effects producing impaired performance and accidents. Nature of task effects, especially tasks requiring sustained attention and monotony, also produced significant performance decrements, but the effects on accidents and/or injury were unresolved because of a lack of studies. The evidence did not support a direct link between circadian-related fatigue influences and performance or safety outcomes and further research is needed to clarify the link. Undoubtedly, circadian variation plays some role in safety outcomes, but the evidence suggests that these effects reflect a combination of time of day and sleep-related factors. Similarly, although some measures of performance show a direct circadian component, others would appear to only do so in combination with sleep-related factors. The review highlighted gaps in the literature and opportunities for further research.

Performance on a simple response time task: Is sleep or work more important for miners?

The purpose of the current study was to investigate the impact of work- and sleep-related factors on an objective measure of response time in a field setting. Thirty-five mining operators working 12-h shift patterns completed daily sleep and work diaries, wore activity monitors continuously and completed palm-based psychomotor vigilance tests (palmPVT) at the start and end of each shift. Linear mixed models were used to test the main effects on response time of roster, timing of test, sleep history and prior wake. The time at which the test occurred was a significant predictor of response time (F₃(,)₄₀₃(.)₄ = 6.72, p < .01) with the end of night shifts being associated with significantly slower response times than the start of night shifts, and the start or end of day shifts. Further, the amount of sleep obtained in the 24h prior to the test was also a significant predictor of response time (F₃(,)₄₀₇(.)₀ = 3.05, p < .01). The results suggest that, as expected, the end of night shift is associated with changes in response time indicative of performance impairments. Of more interest however is that immediate sleep history was also predictive of changes in response time with lower amounts of prior sleep related to slower response times. The current data provides further evidence that sleep is a primary mediator of performance, independent of roster pattern.

Sleep in a live-in mining operation: the influence of start times and restricted non-work activities

The amount of sleep obtained between shifts is influenced by numerous factors including the length of work and rest periods, the timing of the rest period relative to the endogenous circadian cycle and personal choices about the use of non-work time. The current study utilised a real-world live-in mining environment to examine the amount of sleep obtained when access to normal domestic, family and social activities was restricted. Participants were 29 mining operators (26 male, average age 37.4 ± 6.8 years) who recorded sleep, work and fatigue information and wore an activity monitor for a cycle of seven day shifts and seven night shifts (both 12h) followed by either seven or fourteen days off. During the two weeks of work participants lived on-site. Total sleep time was significantly less (p<0.01) while on-site on both day (6.1 ± 1.0 h) and night shifts (5.7 ± 1.5 h) than days off (7.4 ± 1.4 h). Further, night shift sleep was significantly shorter than day-shift sleep (p<0.01). Assessment of subjective fatigue ratings showed that the sleep associated with both days off and night shifts had a greater recovery value than sleep associated with day shifts (p<0.01). While on-site, participants obtained only 6h of sleep indicating that the absence of competing domestic, family and social activities did not convert to more sleep. Factors including shift start times and circadian influences appear to have been more important.

The effects of different roster schedules on sleep in miners

Shiftwork involving early morning starts and night work can affect both sleep and fatigue. This study aimed to assess the impact of different rostering schedules at an Australian mine site on sleep and subjective sleep quality. Participants worked one of four rosters; 4 x 4 (n = 14) 4D4O4N4O 7 x 4 (n = 10) 7D4O7N40 10 x 5 (n = 17) 5D5N50 14 x 7 (n = 12) 7D7N70. Sleep (wrist actigraphy and sleep diaries) was monitored for a full roster cycle including days off. Total sleep time (TST) was longer on days off (7.0 +/- 1.9) compared to sleep when on day (6.0 +/- 1.0) and nightshifts (6.2 +/- 1.6). Despite an increase in TST on days off, this may be insufficient to recover from the severe sleep restriction occurring during work times. Restricted sleep and quick shift-change periods may lead to long-term sleep loss and associated fatigue.

Estimating the Circadian Rhythm in the Risk of Occupational Injuries and Accidents

The authors recently published a prototypic Risk Index (RI) to estimate the risk of critical errors associated with shift systems. This RI was based on published trends in the relative risk of injuries and accidents, and a simple additive model was proposed to estimate the risk for a given shift system. However, extending the RI to irregular work schedules requires an estimation of the phase and amplitude of the circadian rhythm in risk. This paper integrates the published evidence on three independent sources of data that allow such estimations to be made: the trend in risk over a 24 h day, over the course of the night shift, and across the three different (8 h) shifts. Despite potential confounders, maximum risk (i.e., acrophase = peak time) estimates across these three trends showed a remarkable consistency, with all three estimates occurring at about midnight, although the amplitude estimates varied considerably. The best estimate of the amplitude of the circadian rhythm in risk would appear to be that based on trend over the three (8 h) shifts, as this trend is the least confounded. The estimated acrophase (peak time) in risk appeared earlier than would be predicted from consideration of the circadian rhythm in alertness, fatigue, or performance on simple interpolated tasks, such as reaction time or performance on the Psychomotor Vigilance Test.

Sleep Loss and Fatigue in Shift Work and Shift Work Disorder

Shift work is highly prevalent in industrialized societies (>20%) but, when it includes night work, it has pronounced negative effects on sleep, subjective and physiological sleepiness, performance, accident risk, as well as on health outcomes such as cardiovascular disease and certain forms of cancer. The reason is the conflict between the day oriented circadian physiology and the requirement for work and sleep at the "wrong" biological time of day. Other factors that negatively impact work shift sleepiness and accident risk include long duration shifts greater than 12 hours and individual vulnerability for phase intolerance that may lead to a diagnosis of shift work disorder; i.e., those shift workers with the greatest sleepiness and performance impairment during the biological night and insomnia during the biological day. Whereas some countermeasures may be used to ameliorate the negative impact of shift work on nighttime sleepiness and daytime insomnia (combined countermeasures may be the best available), there seems at present to be no way to eliminate most of the negative effects of shift work on human physiology and cognition.

Sleep quality and job satisfaction of Turkish nurses

This research was conducted as a descriptive study for the purpose of examining nurses' sleep quality, job satisfaction, and the relationship between them. The research population was comprised of nurses who work at Inönü University Turgut Ozal Medical Center (Turkey) and the research was conducted with a total of 418 nurses. A Personal Information Form, developed by the researchers based on information in the literature, and the Pittsburgh Sleep Quality Index (PSQI) and Short Form Minnesota Satisfaction Questionnaire (MSQ), which have been adapted for Turkish and had validity and reliability studies conducted, were used for data collection in the research. For data analysis, frequency distribution, arithmetic mean, variance analysis (One-Way ANOVA), Tukey test, and Independent Samples t test were used. According to the findings obtained from the research it was determined that nurses' total sleep quality score mean was 7.28 +/- 3.56 and job satisfaction score mean was 48.05 +/- 11.77 and a weak negative correlation was found between the 2 tools (r = -0.25) (P < .05). As the nurses' sleep quality increased (that is, as their sleep quality score mean decreased) their job satisfaction increased (their job satisfaction score mean increased). In general, the results obtained from our research show that nurses' sleep quality is low and their job satisfaction is at a moderate level. In parallel with this, as the nurses' sleep quality decreases their job satisfaction also decreases.

A systematic review of the neurobehavioural and physiological effects of shiftwork systems

Shiftwork is a common experience for many workers. There are a wide range of shift systems in use, with a number of general approaches and myriad variations of each one. Many aspects of shift systems have been studied, but attempts to reach definitive conclusions about appropriate designs have been hampered by a number of methodological issues. The aim of this systematic review was to provide evidence-based recommendations on the effect of various shift systems on neurobehavioural and physiological functioning and to identify areas which are lacking in appropriate evidence. Two main aspects of shift design were able to be considered-the direction of shift rotation and extended shift length (mainly 12-h shifts). Other areas for which there was at least one relevant paper of adequate methodology were the use of naps during night shifts, the starting time of shifts, and several other specific shift issues. Overall, the review found there is insufficient evidence to support definitive conclusions regarding any of these factors. However, the analysis provides support for the use of forward rotating shift systems in preference to backward rotating shift systems, at last as far as 8-h shifts are concerned. There are many unanswered questions in shift design. For these questions to be answered, it is important that the methodological shortcomings present in most of the studies published to date be overcome.

Altered sleep/wake patterns and mental performance

Altered sleep/wake patterns involve, by definition, displaced sleep. The present review concludes that mental performance is strongly influenced by many forms of displaced sleep. Being exposed to the circadian low (during work/activity), extended time awake or reduced duration of sleep will impair performance. The effect is most pronounced in the laboratory setting, however, even if a number of studies have shown effects of for example night work on neuropsychological tests, and simulated work. In real shift work situations performance changes have been less pronounced. No studies have evaluated the effects on production, but accidents and serious mistakes have been clearly established in road transport and there seems to be clear effects also in health care. The effects are similar in connection with flights across several time zones (jet lag) but less data are available. It is suggested that there is a need for establishing the significance of impaired performance due to work hours in white collar and service work. Also the notion of individual differences in performance impairment is an important issue.

Beyond the three-process model of alertness: estimating phase, time on shift, and successive night effects

This paper starts by summarizing the development and refinement of the additive three-process model of alertness first published by Folkard and Akerstedt in 1987. It reviews some of the successes that have been achieved by the model in not only predicting variations in subjective alertness on abnormal sleep-wake schedules but also in accounting for objective measures of sleep latency and duration. Nevertheless, predictions derived from the model concerning alertness on different shifts, and over successive night shifts, are difficult to reconcile with published data on accident risk. In light of this, we have examined two large sets of alertness ratings with a view to further refining the model and identifying additional factors that may influence alertness at any given point in time. Our results indicate that, at least for the range of sleep durations and wake-up times commonly found on rotating shift systems, we may assume the phase of the endogenous circadian component of alertness (process C) to be "set" by the time of waking. Such an assumption considerably enhanced the predictive power of the model and yielded remarkably similar phase estimates to those obtained by maximizing the post-hoc fit of the model. We then examined the manner in which obtained ratings differed from predicted values over a complete 8-day cycle of two, 12-h shift systems. This revealed a pronounced "first night compensation effect" that resulted in shift workers rating themselves as progressively more alert than would be predicted over the course of the first night shift. However, this appeared to be achieved only at the cost of lowered ratings on the second night shift. Finally, we were able to identify a "time on shift" effect whereby, with the exception of the first night shift, alertness ratings decreased over the course of each shift before showing a modest "end effect." We conclude that the identification of these additional components offers the possibility that in the future we may be able to predict trends in accident risk on abnormal sleep-wake schedules.