The website of the ICOH Committee on Shiftwork and Working Time, a committee of the International Commission on Occupational Health (ICOH)

“In what situations would 8 hour shifts be more beneficial, and when would 12 hour shifts be better?”

A collection of interesting papers collected by WTS-members
(June 2013 - edited by Imelda Wong and Johannes Gaertner)

Title Year Contributor

Citation & Downloadlink
Contributot Notes & Abstract

Circadian Time Organization of Professional Firemen: Desynchronization -Tau Differing from 24.0 Hours -Documented by Longitudinal Self-assessment of 16 Variables
2013
Alain Reinberg

 
CITATION: Reinberg A, Riedel M, Brousse E, Floc'h NL, Clarisse R, Mauvieux B, Touitou Y, Smolensky MH, Marlot M, Berrez S, Mechkouri M. Chronobiol Int. 2013 Oct;30(8):1050-65
DOWNLOAD: http://informahealthcare.com/doi/abs/10.3109/07420528.2013.800087
ABSTRACT/RESULTS:
We investigated the circadian synchronization/desynchronization (by field-study assessment of differences in period, τ, of 16 coexisting and well-documented rhythms) of 30 healthy firemen (FM) exposed to irregular, difficult, and stressful nocturnal work hours who demonstrated excellent clinical tolerance (allochronism). Three groups of FM were studied (A = 12 FM on 24-h duty at the fire station; B = 9 FM on 24-h duty at the emergency call center; C = 9 day-shift administrative FM) of mostly comparable average age, body mass index, career duration, chronotypeundefinedmorningness/eveningness, and trait of field dependence/independence. The self-assessed 16 circadian rhythms were (i) physiological ones of sleep-wake (sleep log), activity-rest (actography), body temperature (internal transmitter pill probe), right- and left-hand grip strength (hand dynamometer), systolic and diastolic blood pressure (BP) plus heart rate (ambulatory BP monitoring device); (ii) psychological ones (visual analog self-rating scales) of sleepiness, fatigue, fitness for work, and capacity to cope with aggressive social behavior; and (iii) cognitive ones of eye-hand skill and letter cancellation, entailing performance speed (tasks completed/unit time) and accuracy (errors). Data (4–6 time points/24 h; 2 591 480 values in total) were gathered continuously throughout two 8-d spans, one in winter 2010–2011 and one in summer 2011. Each of the resulting 938 unequal-interval time series was analyzed by a special power spectrum analysis to objectively determine the prominent τ. The desynchronization ratio (DR: number of study variables with τ  = 24.0 h/number of study variables × 100) served to ascertain the strength/weakness of each rhythm per individual, group, and season. The field study confirmed, independent of group and season, coexistence of rather strong and weak circadian oscillators. Interindividual differences in DR were detected between groups and seasons (χ2, correlation tests, analysis of variance [ANOVA]). Moreover, in each group, both in winter and summer, a normal distribution was observed in the number of FM with rhythms with τ = 24.0 h, e.g., ranging from 5/16 (large desynchronization) to 16/16 (no desynchronization). Such a normal distribution with intraindividual stability over time (i.e., seasons) is consistent with the hypothesis of an inherited origin of a differential propensity to circadian desynchronization and which is supported by the distribution of τs in winter and summer following the Dian-Circadian Genetic Model, i.e., with τ = 24.0 h, τ = 24.0 h + n(0.8 h), and τ = 24.0 h − n(0.8 h)

Working time, health, and safety: a research synthesis paper
2012
 

CITATION: Tucker P., Folkard S.  // Conditions of Work and Employment Series No. 31. – Geneva: ILO, 2012. – 60 p.
DOWNLOAD: http://www.pacts.org.uk/docs/pdf-bank/ILO_fatigue.pdf
ABSTRACT/RESULTS: Compressing the work week into fewer longer shifts (e.g. 12-hour instead of 8-hour shifts) tends to be popular with workers, who appreciate the extended periods of time off and the reduced number of commutes.However, longer shifts require the work effort to be sustained over an extended period without substantial rest. This could, in theory, result in fatigue accumulating to unsafe levels towards the end of the shift.
In summary, the findings regarding the impact of extended shifts on fatigue, well-being, performance and safety are inconsistent. This may be due in part to differences in the nature of the occupations or job-tasks being undertaken by the subjects of the studies (L. Smith, Folkard et al., 1998). For example, unstimulating work environments, monotonous tasks and the requirement to sustain attention all increase the likelihood of performance decrement over prolonged periods, although this may not be due to the development of fatigue per se (Williamson et al., 2011). Long (i.e. 12-hour) shifts may cause increased sleepiness in situations with a high workload, inadequate staff resources, insufficient rest breaks or extended commuting time (Rosa, 1995). In addition, the successful implementation of
extended shifts depends on how those shifts are arranged, for example, in terms of start and finish times (Tucker et al., 1998a, 1998b), the distribution of rest days (Tucker et al., 1999) and the distribution of rest breaks within the shifts (Tucker, 2003; see Section 3). It is therefore difficult to specify a universally applicable recommendation for maximum shift duration. Nevertheless, on the balance of available evidence, and especially in the light of the observed increase in accident risk with extended time on shift, it is recommended that shifts should not be longer than 12 hours in duration.

12-h or 8-h shifts? It depends
2012
Wessel van Leeuwen

CITATION: Sally A. Ferguson and Drew Dawson, Sleep Medicine Reviews 2012 16(6): 519-528
DOWNLOAD: http://www.sciencedirect.com/science/article/pii/S1087079211001213
NOTES: Excellent overview of the literature concerning this topic.
ABSTRACT/RESULTS: Since 12-h shifts were first implemented, the question has been asked – are ‘twelves’ better than ‘eights’? People trying to answer this question invariably refer to the limited literature at their disposal, often piecemeal, small-scale studies comparing 8-h versus 12-h shifts in isolated groups of workers in which many other factors vary concurrently. The narrow perspective and sometimes ‘vested interests’ of the organizations, researchers, publishers and individual workers can influence both the choice of measures, the analysis of results and their interpretation. The current review suggests that it is not sufficient to evaluate a shift pattern on the basis of a single dimension of a working time arrangement, such as shift length. Numerous factors associated with the work practice influence the outcome of a shift pattern including start times, pattern of shifts and amount of overtime. Moreover, the type of work being done and the demographics or characteristics of the workforce are additional mediating factors. Finally, and perhaps most critically, the relative importance assigned to different outcome measures is an important consideration. There are situations where total sleep time might increase following a change to 12-h shifts, whereas domestic life for some workers may deteriorate. Additionally, safety measures may show improvements on 8-h shifts but physical or psychological health outcomes may be worse. The myriad combinations of work pattern, work task, worker and outcome measure under investigation mean that the best way to take account of these complexities may be to use an approach that manages ‘system’ risk. Given the non-linearities in the system, and the fact that current approaches either ignore, or privilege a subset of outcomes, it is perhaps more appropriate to conceptualize working time arrangements as an ‘ecosystem’ and to address the risks in the overall system as opposed to a single dimension such as shift length.

Shift schedule and risk for hypertension and impaired glucose torelance
2012
Tatsuhiko Kubo

CITATION: Tatsuhiko Kubo 2012 (Conference Presentation: 19th Meeting of Japanese Society for Chronobiology) I will search for preferable citation
DOWNLOAD: N/A
NOTES: 12 hour shifts would be beneficial in cases for working situation with prolonged commute time. 12 hour shifts will contribute in decreasing number of commutes and save time for private including sleep hours.
ABSTRACT/RESULTS: N/A

Shift and night work and long working hours--a systematic review of safety implications.
2011
 

CITATION: Wagstaff AS, Sigstad Lie JA.  Scand J Work Environ Health. 2011 May;37(3):173-85.
DOWNLOAD: http://www.sjweh.fi/show_abstract.php?abstract_id=3146
ABSTRACT/RESULTS: The findings are most relevant to safety-critical activities such as the transport and health sectors. Work periods >8 hours carry an increased risk of accidents that cumulates, so that the increased risk of accidents at around 12 hours is twice the risk at 8 hours. Shift work including nights carries a substantial increased risk of accidents, whereas "pure" night work may bring some protection against this effect due to resynchronization. The evaluated studies give no clear indications of any age or gender being specifically susceptible or protected against the effects of work times scheduling on accident risk.

24-Hour Pattern of Work-Related Injury Risk of French Firemen:
Nocturnal Peak Time
2011

Alain Reinberg
CITATION: Riedel M, Berrez S, Pelisse D, Brousse E, Forget C, Marlot M, Smolensky MH, Touitou Y, Reinberg A. Chronobiology Int. 2011 Oct; 28(8): 697-705.
DOWNLOAD: http://informahealthcare.com/doi/abs/10.3109/07420528.2011.603170
ABSTRACT/RESULTS:
The first aim of the study was to assess clock-time patterning of work-related injuries (WRIs) of firemen (FM) of Saône et Loire-71 (France) during the 4-yr span of 1 January 2004 to 31 December 2007. FM of this service are legally required to log every WRI and seek its evaluation by the medical service, whether the WRI was the result of worksite duties or exercise/sport activities at the station. WRI was defined specifically as a (nonexercise, nonsport, and nonemotional/stress) work-associated trauma, verified both by log book and medical records. For the corresponding years, the 24-h pattern of emergency calls (Calls) plus road traffic (Traffic) on the main roads of the service area was also assessed. Relative risk (R) of WRI was calculated as the quantity of WRIs/h divided by the quantity of Call responses/h × 1000, which takes into account the number of at-risk FM/unit time, since each dispatched emergency vehicle is staffed with 4 FM. Comparably trained regular (RFM) and volunteer (VFM) FM experienced a total of 187 WRIs. The 24-h WRI curve patterns of RFM and VFM were correlated (r = 0.4, p < .05), with no histogram difference (p  > .05). Analysis of variance (ANOVA) validated comparable clock-time patterns in WRIs of RFM and VFM each year and each season (all p  < .0001). Thus, time series of the RFM and VFM were pooled, revealing a statistical significant 24-h variation in WRIs (ANOVA, p > .0006; Cosinor analysis, p  < .0001), with peak at 16:00 h and trough at 04:00 h. The 24-h pattern in Traffic, which mirrors that of human activity, with peak 18:00 h and trough 03:00 h, was also verified (ANOVA, p < .0001; Cosinor, p  < .0001). Calls (n = 112,059) resulting in FM responses also exhibited statistically significant 24-h variation, with peak at 20:00 h and trough at 06:00  h. The 24-h pattern of R showed a nocturnal peak at 02:00 h (R = 2.87 ± 0.46; mean ± SEM) and diurnal trough 14:00 h (R = 1.30 ± 0.05) (t test, p < .02); clock-time-related changes in R were further validated by ANOVA (p = .0001) and Cosinor (p  < .0001), with acrophase (peak time, Ø) of 02:43 h ± 68 min (SD). The second aim of the study was to evaluate the relationship between the 24-h patterns of WRIs and lag-time (LT) response (used as a measure of work performance) of FM of the same service to urgent medical calls for out-of-hospital cardiac arrests. Highest R of WRI at 02:00 h corresponded closely to longest LT (raw data at 02:00  h and Cosinor derived Ø of 02.54 h ± 71 min [SD]), thereby supporting the hypothesis of a common mechanism underlying the two 24-h profiles. A third aim was to determine the relevance of a new concept in work safety, “chronoprevention,” for future FM training programs.
24-hour Pattern in Lag Time of Response by Firemen to Calls for Urgent
Medical Aid
2011
Alain Reinberg
CITATION: Brousse E, Forget C, Riedel M, Marlot M, Mechkouri M, Smolensky MH, Touitou Y, Reinberg A. Chronobiol Int. 2011 Apr;28(3):275-81.
DOWNLOAD: https://www.jstage.jst.go.jp/article/indhealth/45/1/45_1_125/_article
ABSTRACT/RESULTS:
The aim of the study was to assess the group 24-h pattern of lag time (LT) in response by regular and volunteer firemen (RFM and VFM) to calls for medical help (CFMH), specifically calls for out-of-hospital cardiac arrest (OHCA). LT, duration in min between a CFMH and departure of service vehicle equipped with a semiautomated defibrillator and generally staffed with four well-trained and ready-to-go FM, represents the integrated duration of several processes, each with separate reaction and decision-making times. The exact time of each CFHM (in min, h, day, month, yr) was recorded electronically, and the exact departure time from the station of the responding FM vehicle was recorded by an on-duty FM. Overall, CFMH made up 53 ± 9% (SEM) of all emergencies calls for aid. To standardize the study methods, the reported findings are based on 568 CFMH specifically regarding OHCA that occurred during the 4-yr study span (January 2005 to December 2008). CFMH exhibited a 24-h pattern with a major peak at 10:00 h (mean ± SEM: n = 9.5 ± 1.6) and major trough at 01:00 h (n = 1.3 ± 0.3; t test, p < .001). From year to year and season to season, a 24-h pattern was detected in the total of CFMH/h with two peaks (10:00 and 17:00h) and two troughs (01:00 and 15:00 h) (analysis of variance [ANOVA], p < .01; Cosinor, p < .05 to < .003), with neither season- nor year-related differences (χ2, p > .05). In CFMH/h pooled time series, ANOVA-detected differences between the hourly means (p < .01), and Cosinor analysis validated a 24-h rhythm (p  < .002). In raw data, the longest LT, indicative of poorest performance, occurred at 05:00 h (8.8 ± 0.7 min) and the trough of LT, indicative of best performance, at 16:00 h (4.3 ± 0.8 min (t test, p < .02). 24-h patterning in LT was validated both by ANOVA of hourly means (p < .0006) and Cosinor analysis (p < .05), with longest LT 05:00 h and shortest LT 16.00  h for data of the individual yearly time-series data. The 24-h LT rhythm was also validated in the pooled time series by Cosinor (p  < .0001), with the 24-h mean ± SEM = 6 ± 0.17 min and acrophase (peak) of 03:00 h ± 88 min (SD). Curve patterns of CFMH/h and LT/h differed widely. As a group phenomenon, the LT 24-h rhythm mimics the 24-h pattern of performance, as demonstrated by many laboratory and field investigations. The stability of the LT rhythm between years and seasons and its weak relationship with the CFMH 24-h pattern favors the hypothesis of an endogenous component or origin. The nighttime trough of performance is presumably linked to the elevated risk of work accidents in the same population of FM.

Associations between work schedule characteristics and occupational injury and illness.
2010
 

CITATION: de Castro AB, Fujishiro K, Rue T, Tagalog EA, Samaco-Paquiz LP, Gee GC.  Int Nurs Rev. 2010 Jun;57(2):188-94.
DOWNLOAD: http://onlinelibrary.wiley.com/doi/10.1111/j.1466-7657.2009.00793.x/abstract
ABSTRACT/RESULTS: Neither hours worked per week nor shift length was significantly associated with work-related injury, work-related illness, missed work and back pain

Age-related safety in professional heavy vehicle drivers: a literature review
2010
 

CITATION: Duke J, Guest M, Boggess M. // Accid Anal Prev. 2010 Mar;42(2):364-71.
DOWNLOAD: http://www.sciencedirect.com/science/journal/00014575/42/2
ABSTRACT/RESULTS: Other contributing factors to heavy vehicle accidents include: long hours and subsequent sleepiness and fatigue, employer safety culture, vehicle configuration particularly multiple trailers, urbanisation and road classification.

Is it time to pull the plug on 12-hour shifts? Part 3. harm reduction strategies if keeping 12-hour shifts.
2010
 

CITATION:  Geiger-Brown J, Trinkoff AM.  J Nurs Adm. 2010 Sep;40(9):357-9.
DOWNLOAD: http://journals.lww.com/jonajournal/toc/2010/09000
ABSTRACT/RESULTS: this is part of a 3 part series:

Part 1: Shift durations of 12 hours or more are now ubiquitous in hospitals, with currently working staff nurses reporting satisfaction with this shift length, although others who prefer shorter work hours have generally left hospital nursing. Nurse administrators are beginning to question the wisdom of having nurses work extended hours. In part 1 of this 2-part series, the authors provide an update on recent findings that challenge the current scheduling paradigm that supports unsafe long work hours.

Part 2: Obstacles that nurse administrators face when they "buck the 12-hour trend" and offers guidance for introducing work schedule changes.

This article is part 3 of the series "Pulling the Plug on 12-Hour Shifts." In part 1 (March 2010), the authors provided an update on recent evidence that challenges the current scheduling paradigm and supports the lack of safety of long work hours. Part 2 (April 2010) described the barriers to change and challenges for the nurse executive in moving away from the practice of 12-hour shifts. This article presents strategies for mitigating the effects of 12-hour shifts for nurses who continue to work 12-hour shifts despite the potential risks to their health and to patient safety.

Shift Work and Extended Working Hours as Risk Factors for Occupational Injury
2010
Imelda Wong

CITATION: Salimen, S.(2010) The Ergonomics Open Journal. Volume 3, p 14 - 18
DOWNLOAD: http://www.benthamscience.com/open/toergj/articles/V003/14TOERGJ.pdf
ABSTRACT/RESULTS: The aim of this review is to examine the effect of shift work and extended working hours on occupational injuries. A calculation based on four studies shows that the risk of occupational injury during afternoon shifts was 6% lower than that during morning shifts. The same kind of calculation showed that the risk of occupational injury during night shifts was 15% lower than during morning shifts. A review of eight studies showed that the risk of occupational injury was 41% higher for 10-hour working days compared to 8-hour working days. On the other hand, working 12-hour days increased the risk of occupational injury by 14%. When working more than 12 hours per day, three studies showed a 98% increase in involvement in occupational injury. The results of this study showed that shift work considerably increased the risk of occupational injury in the USA, but not in the other countries. Extended working hours was related to elevated risk of occupational injury. Thus shift work and long work hours did not suit for all employees

Extended Work Periods
2007
 

CITATION: Knauth, P., Industrial Health No. 1, Vol. 45, 125 - 136, 2007
DOWNLOAD: https://www.jstage.jst.go.jp/article/indhealth/45/1/45_1_125/_article
ABSTRACT/RESULTS: A literature review of 105 studies on the effects of extended daily working hours was conducted. Potential negative effects of extended working hours are discussed: More accidents on the job; more accidents off the job; reduced duration and quality of sleep due to moonlighting; sleepiness; reduced alertness; fatigue; adverse effects on performance; prolonged toxic exposure; adverse effects on health; increased absenteeism; problems communicating with managers; and problems while driving home. Potential positive effects of extended working hours are discussed: Less travel time and costs; more time for the family, social life, and domestic duties; increased satisfaction with working hours; fewer handovers; and less overtime. No firm conclusions can be drawn because of the partly contradictory results and the methodological problems of many studies. However, caution is advised when considering the introduction of extended work shifts, particularly where public safety is at stake. A checklist is provided (concerning work load, breaks, staffing level, systematic assessments of health and safety factors) to support decisions for or against the use of extended work shifts.

Associations between employees' work schedules and the vocational consequences of workplace injuries
2007
 

CITATION: Dembe AE, Delbos R, Erickson JB, Banks SM.  J Occup Rehabil. 2007 Dec;17(4):641-51.
DOWNLOAD: http://link.springer.com/article/10.1007/s10926-007-9098-8
ABSTRACT/RESULTS: The most prominent effects of working a nonstandard schedule were a increased risk of being fired (OR = 1.81; 1.15-2.90 CI 95%), quitting (OR = 1.68; 1.20-2.36 CI 95%), or being unable to work full time (OR = 1.33; 1.08-1.64 CI 95%) following an injury, compared to injured workers in conventional schedules. Schedules involving overtime and long working hours generally had a greater impact on vocational consequences following a workplace injury than did schedules involving night, evening, and other nonstandard shift work.

[Rest for safety: which stakes?].
2007
 

CITATION: Mion G, Ricouard S.  Ann Fr Anesth Reanim. 2007 Jul-Aug;26(7-8):638-48.
DOWNLOAD: N/A
ABSTRACT/RESULTS: N/A

Health problems due to long working hours in Japan: working hours, workers' compensation (Karoshi), and preventive measures.
2006
 

CITATION: Iwasaki K, Takahashi M, Nakata A.  Ind Health. 2006 Oct;44(4):537-40.
DOWNLOAD: http://www.jniosh.go.jp/en/indu_hel/pdf/indhealth_44_4_537.pdf
ABSTRACT/RESULTS: Late in the 1970s, serious social concern over health problems due to long working hours has arisen in Japan. This report briefly summarizes the Japanese circumstances about long working hours and what the Government has achieved so far. The national statistics show that more than 6 million people worked for 60 h or more per week during years 2000 and 2004. Approximately three hundred cases of brain and heart diseases were recognized as labour accidents resulting from overwork (Karoshi) by the Ministry of Health, Labour and Welfare (MHLW) between 2002 and 2005. Consequently, the MHLW has been working to establish a more appropriate compensation system for Karoshi, as well as preventive measures for overwork related health problems. In 2001, the MHLW set the standards for clearly recognizing Karoshi in association with the amount of overtime working hours. These standards were based on the results of a literature review and medical examinations indicating a relationship between overwork and brain and heart diseases. In 2002, the MHLW launched the program for the prevention of health impairment due to overwork, and in 2005 the health guidance through an interview by a doctor for overworked workers has been enacted as law. Long working hours are controversial issues because of conflicts between health, safety, work-life balance, and productivity. It is obvious that we need to continue research regarding the impact on worker health and the management of long working hours

Compressed working weeks
2006
Philip Tucker

CITATION: Tucker, P. (2006). Compressed working weeks. Conditions of Work and Employment Series No. 12. International Labour Office: Geneva.
DOWNLOAD: http://www.ilo.org/wcmsp5/groups/public/---ed_protect/---protrav/---travail/documents/publication/wcms_travail_pub_12.pdf
NOTES: A comprehensive review of research (up to 2006) examining compressed working weeks. The majority of studies involve comparisons between 8h and 12h shifts, although other shift lengths are examined, as are short inter-shift intervals ("quick returns")
ABSTRACT/RESULTS: Several studies suggest overall improvements in sleep with the move from eight- to 12-hour shifts. This seems to be because the latter often allow for a greater number of normal nights of sleep over the shift cycle. However, some studies have identified decrements in sleep,particularly associated with12-hour night shifts. Compressed work weeks (CWW) schedules should try to incorporate change-overs timed so as to optimize sleep for workers coming onto, and going off, shift. They should also avoid quick returns. Taken as a whole, the evidence suggests that a well-designed CWW should not lead to chronic sleep deprivation, so long as the job is not too demanding. However, there may also be problems of acute fatigue at certain points within the shift cycle. In particular, several studies have identified heightened levels of fatigue towards the end of 12-hour shifts. Such increases in fatigue maybe greater in high-demand environments. While there is some limited evidence that a change from eight- to 10-hour shifts maybe less problematic, further research is needed on this form of CWW. There is also evidence (albeit limited) of heightened fatigue following quick returns. The acute fatigue effects of extended shifts and quick returns appear to stem largely from the impact of the CWW schedules on sleep taken prior to particular shifts. Therefore the design of CWW schedules should aim to minimize the disruption of sleep, and also to optimize recovery, both during and between shifts

Extended work shifts and the risk of motor vehicle crashes among interns.
2005
 

CITATION: Barger LK, Cade BE, Ayas NT, Cronin JW, Rosner B, Speizer FE, Czeisler CA;  N Engl J Med. 2005 Jan 13;352(2):125-34.
DOWNLOAD: http://www.nejm.org.myaccess.library.utoronto.ca/doi/full/10.1056/NEJMoa041401
ABSTRACT/RESULTS: The odds ratios for reporting a motor vehicle crash and for reporting a near-miss incident after an extended work shift (>= 24 hours) , as compared with a shift that was not of extended duration, were 2.3 (95 percent confidence interval, 1.6 to 3.3) and 5.9 (95 percent confidence interval, 5.4 to 6.3), respectively. In a prospective analysis, every extended work shift that was scheduled in a month increased the monthly risk of a motor vehicle crash by 9.1 percent (95 percent confidence interval, 3.4 to 14.7 percent) and increased the monthly risk of a crash during the commute from work by 16.2 percent (95 percent confidence interval, 7.8 to 24.7 percent). In months in which interns worked five or more extended shifts, the risk that they would fall asleep while driving or while stopped in traffic was significantly increased (odds ratios, 2.39 [95 percent confidence interval, 2.31 to 2.46] and 3.69 [95 percent confidence interval, 3.60 to 3.77], respectively).

The impact of overtime and long work hours on occupational injuries and illnesses: new evidence from the United States.
2005
 

CITATION: Dembe AE, Erickson JB, Delbos RG, Banks SM.  Occup Environ Med. 2005 Sep;62(9):588-97.
DOWNLOAD: http://oem.bmj.com/content/62/9.toc
ABSTRACT/RESULTS: RESULTS: After adjusting for those factors, working in jobs with overtime schedules was associated with a 61% higher injury hazard rate compared to jobs without overtime. Working at least 12 hours per day was associated with a 37% increased hazard rate and working at least 60 hours per week was associated with a 23% increased hazard rate. A strong dose-response effect was observed, with the injury rate (per 100 accumulated worker-years in a particular schedule) increasing in correspondence to the number of hours per day (or per week) in the workers' customary schedule.

Conclusion: Results suggest that job schedules with long working hours are not more risky merely because they are concentrated in inherently hazardous industries or occupations, or because people working long hours spend more total time "at risk" for a work injury. Strategies to prevent work injuries should consider changes in scheduling practices, job redesign, and health protection programmes for people working in jobs involving overtime and extended hours

A survey of forest workers in New Zealand. Do hours of work, rest, and recovery play a role in accidents and injury?
2002
 

CITATION:  Lilley R, Feyer AM, Kirk P, Gander P. J Safety Res. 2002 Spring;33(1):53-71.
DOWNLOAD: http://www.sciencedirect.com/science/article/pii/S0022437502000038
ABSTRACT/RESULTS: Fatigue was found to be commonly experienced at work in the forest, with 78% of workers reporting that they experienced fatigue at least "sometimes." This study found that certain groups of workers reported long working hours, reduced sleep, compromised recovery time, and intensely paced work. The results of logistic regression analysis showed that recent sleep, number of breaks taken during the workday, and specific job/tasks were independently associated with reporting of high fatigue levels at work. Near-miss injury events were significantly more common among those reporting a high level of fatigue at work. Accidents and lost-time injury were associated with length of time at work, ethnicity, and having had near-miss injury events.

Health and safety among film technicians working extended shifts.
2001
 

CITATION: Bourdouxhe M, Toulouse G. J Hum Ergol (Tokyo). 2001 Dec;30(1-2):113-8.
DOWNLOAD: http://jlc.jst.go.jp/JST.Journalarchive/jhe1972/30.113
ABSTRACT/RESULTS: This paper presents selected results from a pilot research. The study of film technicians' work schedules and occupational hazards was based on a questionnaire administered to all 2200 film technicians (650 valid replies; response rate = 30%), interviews with producers and technicians on film-shooting organization and scheduling, courses in film technique, individual interviews with workers in trade at high risk, and review of the literature on freelancers, on the effects of intermittent work, and on risk factors for musculoskeletal injuries. Work schedules showed a tendency to extremely long work shifts (14 hours per day on average, and up to 19 hours in some trades). Occupational constraints and work schedules were found to relate to an increased risk of work-related injuries. Technicians identified fatigue associated with work schedules as the principal risk of accidents and one of the factors responsible for causing or aggravating their many musculoskeletal injuries. Work schedules were not the only cause of these injuries: stress--due to time constraints, work responsibilities and job insecurity--was also an important risk factor, consistent with the literature on musculoskeletal disorders. Physical workload was also problematic, particularly when demanding tasks had to be performed under severe time constraints.

Extended working hours and accident risk
2000
 

CITATION: Nachreiner, F. "Extended work hours and accident risk." Shiftwork (2000): 29-44.
DOWNLOAD: N/A
ABSTRACT/RESULTS: N/A

Shiftwork 2000. Implications for science, practice and business
2000
 

CITATION: T. Marek, H. Oginska, J. Pokorski [e. a.] (eds). – Krakow: Jagiellonian University, 2000. 
DOWNLOAD: Book
ABSTRACT/RESULTS: N/A

Factors associated with falling asleep at the wheel among long-distance truck drivers.
2000
 

CITATION: McCartt AT, Rohrbaugh JW, Hammer MC, Fuller SZ. Accid Anal Prev. 2000 Jul;32(4):493-504
DOWNLOAD: http://www.sciencedirect.com/science/article/pii/S0001457599000676
ABSTRACT/RESULTS: Data on the prevalence and hypothesized predictors of falling asleep while driving were gathered through face-to-face interviews with 593 long-distance truck drivers randomly selected at public and private rest areas and routine roadside truck safety inspections. Hypothesized predictor variables related to drivers' typical work and rest patterns, extent of daytime and night-time drowsiness, symptoms of sleep disorder, measures of driving exposure, and demographic characteristics. A sizeable proportion of long-distance truck drivers reported falling asleep at the wheel of the truck: 47.1% of the survey respondents had ever fallen asleep at the wheel of a truck, and 25.4% had fallen asleep at the wheel in the past year. Factor analysis reduced the large set of predictors to six underlying, independent factors: greater daytime sleepiness; more arduous schedules, with more hours of work and fewer hours off-duty; older, more experienced drivers; shorter, poorer sleep on road; symptoms of sleep disorder; and greater tendency to night-time drowsy driving. Based on multivariate logistic regression, all six factors were predictive of self-reported falling asleep at the wheel. Falling asleep was also associated with not having been alerted by driving over shoulder rumble strips. The results suggest that countermeasures that limit drivers' work hours and enable drivers to get adequate rest and that identify drivers with sleep disorders are appropriate methods to reduce sleepiness-related driving by truck drivers.

BEST No.10 Compressed Working Time
2000
Johannes Gärtner

CITATION: Alexander Wedderburn, ISBN 1017-4877 Catalogue no: SY-AB-96-002-EN-C Published: 12 April, 2000
DOWNLOAD: http://www.eurofound.europa.eu/pubdocs/1996/45/en/1/ef9645en.pdf
NOTES: While it was published some years back it reviews a lot of research that has been done in this area.
ABSTRACT/RESULTS: N/A

Nurses' workload associated with 16-h night shifts on the 2-shift system. I: Comparison with the 3-shift system
1999
 

CITATION: Fukuda H., Takahashi M., Airto H.Fukuda H. / // Psychiatry Clin. Neurosci. – 1999. – 53, № 2. – P. 219–221.
DOWNLOAD: http://onlinelibrary.wiley.com/doi/10.1046/j.1440-1819.1999.00544.x/pdf
ABSTRACT/RESULTS: To assess nurses' workload with 16-h night shifts on a 2-shift system, we investigated the differences between workloads with each shift on the 2- and 3-shift systems with questionnaires on subjective symptoms and measuring heart rate and physical activity. It was found that the 2-shift nurses during the 16-h night shifts complained of fatigue less frequently and showed general decreases in heart rate and physical activity compared with the 3-shift nurses during 8-h evening and night shifts. The results suggest that a 2-h nap, an increase of staff, and a day off may reduce the nurses' workload when they have 16-h night shifts

Long distance driving and self-induced sleep deprivation among automobile drivers.
1999
 

CITATION: Philip P, Taillard J, Guilleminault C, Quera Salva MA, Bioulac B, Ohayon M. Sleep. 1999 Jun 15;22(4):475-80.
DOWNLOAD: http://www.journalsleep.org/ViewAbstract.aspx?pid=24090
ABSTRACT/RESULTS: RESULTS:
Fifty percent of the drivers decreased their total sleep time in the 24 hours before the interview compared with their regular self-reported sleep time. 12.5% presented a sleep debt > 180 minutes, and 2.7% presented a sleep debt > 300 minutes. Being young, commuting to work, driving long distances, starting the trip at night, being an "evening" person, being a long sleeper during the week, and sleeping in on the week-end were risk factors significantly associated with sleep debt.

Conclusion:
The results of the study highlight variables (long-distance driving, youth, sleep restriction) that are frequently associated with sleep-related accidents.

Work injuries and time of day
1998
 

CITATION: National data / Akerstedt T. // Shiftwork Int. Newsletter. – 1995. – 12, № 1. – P. 2.
DOWNLOAD: N/A
ABSTRACT/RESULTS: N/A

Accident risk as a function of hour at work and time of day as determined from accident data and exposure models for the German working population.
1998
 

CITATION: Hänecke K, Tiedemann S, Nachreiner F, Grzech-Sukalo H. Scand J Work Environ Health. 1998;24 Suppl 3:43-8.
DOWNLOAD: http://www.sjweh.fi/show_abstract.php?abstract_id=334
ABSTRACT/RESULTS: An exponentially increasing accident risk was observed beyond the 9th hour at work. The relative accident risks differed considerably according to the respective exposure model with regard to time of day. A highly significant interaction effect was found for hour at work by time of day, the percentage of accidents at different hours at work varying according to the particular time of day when work is started. For the 3 "traditional" shiftwork starting times, it was shown that, with later starting times, the relative accident risk increased dramatically beyond the 8th hour at work.

Work shift duration: a review comparing eight hour and 12 hour shift systems.
1998
Imelda Wong

CITATION: Smith L, Folkard S, Tucker P, Macdonald I. Occup Environ Med. 1998 Apr;55(4):217-29.
DOWNLOAD: http://www-ncbi-nlm-nih-gov.myaccess.library.utoronto.ca/pmc/articles/PMC1757571/
ABSTRACT/RESULTS: The research findings are largely equivocal. The bulk of the evidence suggests few differences between eight and 12 hour shifts in the way they affect people. There may even be advantages to 12 hour shifts in terms of lower stress levels, better physical and psychological wellbeing, improved durations and quality of off duty sleep as well as improvements in family relations. On the negative side, the main concerns are fatigue and safety. It is noted that a 12 hour shift does not equate with being active for only 12 hours.

Change from an 8-hour shift to a 12-hour shift, attitudes, sleep, sleepiness and performance.
1998
Lowden Sweden

CITATION: Lowden A, Kecklund G, Åkerstedt T. Scandinavian Journal of Work, Environment & Health 1998:24(suppl 3), 69-75.
DOWNLOAD: https://www.researchgate.net/publication/13371969_Change_from_an_8-hour_shift_to_a_12-hour_shift_attitudes_sleep_sleepiness_and_performance?ev=prf_pub
NOTES: Arne
ABSTRACT/RESULTS: The present study sought to evaluate the effect of a change from a rotating 3-shift (8-hour) to a 2-shift shift (12 hour) schedule on sleep, sleepiness, performance, perceived health, and well-being.

Thirty-two shift workers at a chemical plant (control room operators) responded to a questionnaire a few months before a change was made in their shift schedule and 10 months after the change. Fourteen workers also filled out a diary, carried activity loggers, and carried out reaction-time tests (beginning and end of shift). Fourteen day workers served as a reference group for the questionnaires and 9 were intensively studied during a week with workdays and a free weekend.

The questionnaire data showed that the shift change increased satisfaction with workhours, sleep, and time for social activities. Health, perceived accident risk, and reaction-time performance were not negatively affected. Alertness improved and subjective recovery time after night work decreased. The quick changes in the 8-hour schedule greatly increased sleep problems and fatigue. Sleepiness integrated across the entire shift cycle showed that the shift workers were less alert than the day workers, across workdays and days off (although alertness increased with the 12-hour shift).

The change from 8-hour to 12-hour shifts was positive in most respects, possibly due to the shorter sequences of the workdays, the longer sequences of consecutive days off, the fewer types of shifts (easier planning), and the elimination of quick changes. The results may differ in groups with a higher work load.

Health and safety problems associated with long working hours: a review of the current position
1997
 

CITATION: Spurgeon A. / Spurgeon A., Harrington J. M., Cooper C.L. // Occup. Environ. Med. – 1997. – 54, № 6. – P. 367–375.
DOWNLOAD: http://oem.bmj.com/content/54/6.toc
ABSTRACT/RESULTS: The European Community Directive on Working Time, which should have been implemented in member states of the European Community by November 1996, contains several requirements related to working hours, including the right of employees to refuse to work more than 48 hours a week. The United Kingdom government attempted to oppose the Directive, arguing that there is no convincing evidence that hours of work should be limited on health and safety grounds. Much of the research in this area has focused on the problems of shiftworking and previous reviews have therefore tended to emphasise this aspect of working hours. However, there is much less information about the effects of overtime work, which is a central element of the terms of the Directive. This paper reviews the current evidence relating to the potential effects on health and performance of extensions to the normal working day. Several gaps in the literature are identified. Research to date has been restricted to a limited range of health outcomes--namely, mental health and cardiovascular disorders. Other potential effects which are normally associated with stress--for example, gastrointestinal disorders, musculoskeletal disorders, and problems associated with depression of the immune system, have received little attention. Also, there have been few systematic investigations of performance effects, and little consideration of the implications for occupational exposure limits of extensions to the working day. Existing data relate largely to situations where working hours exceed 50 a week and there is a lack of information on hours below this level, which is of direct relevance to the European Community proposal. Finally, it is clear from investigations relating to shiftwork that a range of modifying factors are likely to influence the level and nature of health and performance outcomes. These include the attitudes and motivation of the people concerned, the job requirements, and other aspects of the organisational and cultural climate. It is concluded that there is currently sufficient evidence to raise concerns about the risks to health and safety of long working hours. However, much more work is required to define the level and nature of those risks

However, examination of the literature relating exclusively to long hours shows that investigations have so far largely been limited to mental health and cardiovascular effects. There is also a limited but growing literature on the consequences for performance and safety, although little information on the implications for control of chemical and other exposures.

Shiftwork. Problems and Solutions
1996
 

CITATION: Folkard S. Effects on performance efficiency / Folkard S. // / W. P. Colquhoun, G. Costa, S. Folkard, P. Knauth (eds). – Frankfurt am Main; Berlin; Bern; New York; Paris;Wien: Lang, 1996. – P. 65-87.
DOWNLOAD: Book
ABSTRACT/RESULTS: Early review of studies published before 1996. See section 3.7 (Shift Duration). Exponential increased risk of injury with 12 hour shifts.

Working time, health, and safety: a research synthesis paper
2012
 

CITATION: Tucker P., Folkard S.  // Conditions of Work and Employment Series No. 31. – Geneva: ILO, 2012. – 60 p.
DOWNLOAD: http://www.pacts.org.uk/docs/pdf-bank/ILO_fatigue.pdf
ABSTRACT/RESULTS: Compressing the work week into fewer longer shifts (e.g. 12-hour instead of 8-hour shifts) tends to be popular with workers, who appreciate the extended periods of time off and the reduced number of commutes.However, longer shifts require the work effort to be sustained over an extended period without substantial rest. This could, in theory, result in fatigue accumulating to unsafe levels towards the end of the shift.

In summary, the findings regarding the impact of extended shifts on fatigue, well-being, performance
and safety are inconsistent. This may be due in part to differences in the nature of the occupations or
job-tasks being undertaken by the subjects of the studies (L. Smith, Folkard et al., 1998). For example,
unstimulating work environments, monotonous tasks and the requirement to sustain attention all
increase the likelihood of performance decrement over prolonged periods, although this may not be due
to the development of fatigue per se (Williamson et al., 2011). Long (i.e. 12-hour) shifts may cause
increased sleepiness in situations with a high workload, inadequate staff resources, insufficient rest
breaks or extended commuting time (Rosa, 1995). In addition, the successful implementation of
extended shifts depends on how those shifts are arranged, for example, in terms of start and finish times
(Tucker et al., 1998a, 1998b), the distribution of rest days (Tucker et al., 1999) and the distribution of
rest breaks within the shifts (Tucker, 2003; see Section 3). It is therefore difficult to specify a
universally applicable recommendation for maximum shift duration. Nevertheless, on the balance of
available evidence, and especially in the light of the observed increase in accident risk with extended
time on shift, it is recommended that shifts should not be longer than 12 hours in duration.

12-h or 8-h shifts? It depends
2012
Wessel van Leeuwen

CITATION: Sally A. Ferguson and Drew Dawson, Sleep Medicine Reviews 2012 16(6): 519-528
DOWNLOAD: http://www.sciencedirect.com/science/article/pii/S1087079211001213
NOTES: Excellent overview of the literature concerning this topic.
ABSTRACT/RESULTS: Since 12-h shifts were first implemented, the question has been asked – are ‘twelves’ better than ‘eights’? People trying to answer this question invariably refer to the limited literature at their disposal, often piecemeal, small-scale studies comparing 8-h versus 12-h shifts in isolated groups of workers in which many other factors vary concurrently. The narrow perspective and sometimes ‘vested interests’ of the organizations, researchers, publishers and individual workers can influence both the choice of measures, the analysis of results and their interpretation. The current review suggests that it is not sufficient to evaluate a shift pattern on the basis of a single dimension of a working time arrangement, such as shift length. Numerous factors associated with the work practice influence the outcome of a shift pattern including start times, pattern of shifts and amount of overtime. Moreover, the type of work being done and the demographics or characteristics of the workforce are additional mediating factors. Finally, and perhaps most critically, the relative importance assigned to different outcome measures is an important consideration. There are situations where total sleep time might increase following a change to 12-h shifts, whereas domestic life for some workers may deteriorate. Additionally, safety measures may show improvements on 8-h shifts but physical or psychological health outcomes may be worse. The myriad combinations of work pattern, work task, worker and outcome measure under investigation mean that the best way to take account of these complexities may be to use an approach that manages ‘system’ risk. Given the non-linearities in the system, and the fact that current approaches either ignore, or privilege a subset of outcomes, it is perhaps more appropriate to conceptualize working time arrangements as an ‘ecosystem’ and to address the risks in the overall system as opposed to a single dimension such as shift length.

Shift schedule and risk for hypertension and impaired glucose torelance
2012
Tatsuhiko Kubo

CITATION: Tatsuhiko Kubo 2012 (Conference Presentation: 19th Meeting of Japanese Society for Chronobiology) I will search for preferable citation
DOWNLOAD: N/A
NOTES: 12 hour shifts would be beneficial in cases for working situation with prolonged commute time. 12 hour shifts will contribute in decreasing number of commutes and save time for private including sleep hours.
ABSTRACT/RESULTS: N/A

Shift and night work and long working hours--a systematic review of safety implications.
2011
 

CITATION: Wagstaff AS, Sigstad Lie JA.  Scand J Work Environ Health. 2011 May;37(3):173-85.
DOWNLOAD: http://www.sjweh.fi/show_abstract.php?abstract_id=3146
ABSTRACT/RESULTS: The findings are most relevant to safety-critical activities such as the transport and health sectors. Work periods >8 hours carry an increased risk of accidents that cumulates, so that the increased risk of accidents at around 12 hours is twice the risk at 8 hours. Shift work including nights carries a substantial increased risk of accidents, whereas "pure" night work may bring some protection against this effect due to resynchronization. The evaluated studies give no clear indications of any age or gender being specifically susceptible or protected against the effects of work times scheduling on accident risk.

Associations between work schedule characteristics and occupational injury and illness.
2010
 

CITATION: de Castro AB, Fujishiro K, Rue T, Tagalog EA, Samaco-Paquiz LP, Gee GC.  Int Nurs Rev. 2010 Jun;57(2):188-94.
DOWNLOAD: http://onlinelibrary.wiley.com/doi/10.1111/j.1466-7657.2009.00793.x/abstract
ABSTRACT/RESULTS: Neither hours worked per week nor shift length was significantly associated with work-related injury, work-related illness, missed work and back pain

Age-related safety in professional heavy vehicle drivers: a literature review
2010
 

CITATION: Duke J, Guest M, Boggess M. // Accid Anal Prev. 2010 Mar;42(2):364-71.
DOWNLOAD: http://www.sciencedirect.com/science/journal/00014575/42/2
ABSTRACT/RESULTS: Other contributing factors to heavy vehicle accidents include: long hours and subsequent sleepiness and fatigue, employer safety culture, vehicle configuration particularly multiple trailers, urbanisation and road classification.

Is it time to pull the plug on 12-hour shifts? Part 3. harm reduction strategies if keeping 12-hour shifts.
2010
 

CITATION:  Geiger-Brown J, Trinkoff AM.  J Nurs Adm. 2010 Sep;40(9):357-9.
DOWNLOAD: http://journals.lww.com/jonajournal/toc/2010/09000
ABSTRACT/RESULTS: this is part of a 3 part series:

Part 1: Shift durations of 12 hours or more are now ubiquitous in hospitals, with currently working staff nurses reporting satisfaction with this shift length, although others who prefer shorter work hours have generally left hospital nursing. Nurse administrators are beginning to question the wisdom of having nurses work extended hours. In part 1 of this 2-part series, the authors provide an update on recent findings that challenge the current scheduling paradigm that supports unsafe long work hours.

Part 2: Obstacles that nurse administrators face when they "buck the 12-hour trend" and offers guidance for introducing work schedule changes.

This article is part 3 of the series "Pulling the Plug on 12-Hour Shifts." In part 1 (March 2010), the authors provided an update on recent evidence that challenges the current scheduling paradigm and supports the lack of safety of long work hours. Part 2 (April 2010) described the barriers to change and challenges for the nurse executive in moving away from the practice of 12-hour shifts. This article presents strategies for mitigating the effects of 12-hour shifts for nurses who continue to work 12-hour shifts despite the potential risks to their health and to patient safety.

Shift Work and Extended Working Hours as Risk Factors for Occupational Injury
2010
Imelda Wong

CITATION: Salimen, S.(2010) The Ergonomics Open Journal. Volume 3, p 14 - 18
DOWNLOAD: http://www.benthamscience.com/open/toergj/articles/V003/14TOERGJ.pdf
ABSTRACT/RESULTS: The aim of this review is to examine the effect of shift work and extended working hours on occupational injuries. A calculation based on four studies shows that the risk of occupational injury during afternoon shifts was 6% lower than that during morning shifts. The same kind of calculation showed that the risk of occupational injury during night shifts was 15% lower than during morning shifts. A review of eight studies showed that the risk of occupational injury was 41% higher for 10-hour working days compared to 8-hour working days. On the other hand, working 12-hour days increased the risk of occupational injury by 14%. When working more than 12 hours per day, three studies showed a 98% increase in involvement in occupational injury. The results of this study showed that shift work considerably increased the risk of occupational injury in the USA, but not in the other countries. Extended working hours was related to elevated risk of occupational injury. Thus shift work and long work hours did not suit for all employees

Extended Work Periods
2007
 

CITATION: Knauth, P., Industrial Health No. 1, Vol. 45, 125 - 136, 2007
DOWNLOAD: https://www.jstage.jst.go.jp/article/indhealth/45/1/45_1_125/_article
ABSTRACT/RESULTS: A literature review of 105 studies on the effects of extended daily working hours was conducted. Potential negative effects of extended working hours are discussed: More accidents on the job; more accidents off the job; reduced duration and quality of sleep due to moonlighting; sleepiness; reduced alertness; fatigue; adverse effects on performance; prolonged toxic exposure; adverse effects on health; increased absenteeism; problems communicating with managers; and problems while driving home. Potential positive effects of extended working hours are discussed: Less travel time and costs; more time for the family, social life, and domestic duties; increased satisfaction with working hours; fewer handovers; and less overtime. No firm conclusions can be drawn because of the partly contradictory results and the methodological problems of many studies. However, caution is advised when considering the introduction of extended work shifts, particularly where public safety is at stake. A checklist is provided (concerning work load, breaks, staffing level, systematic assessments of health and safety factors) to support decisions for or against the use of extended work shifts.

Associations between employees' work schedules and the vocational consequences of workplace injuries
2007
 

CITATION: Dembe AE, Delbos R, Erickson JB, Banks SM.  J Occup Rehabil. 2007 Dec;17(4):641-51.
DOWNLOAD: http://link.springer.com/article/10.1007/s10926-007-9098-8
ABSTRACT/RESULTS: The most prominent effects of working a nonstandard schedule were a increased risk of being fired (OR = 1.81; 1.15-2.90 CI 95%), quitting (OR = 1.68; 1.20-2.36 CI 95%), or being unable to work full time (OR = 1.33; 1.08-1.64 CI 95%) following an injury, compared to injured workers in conventional schedules. Schedules involving overtime and long working hours generally had a greater impact on vocational consequences following a workplace injury than did schedules involving night, evening, and other nonstandard shift work.

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