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Advantages and Disadvantages of 12 Hour Rostering

12 Hour Rosters - Advantages and Disadvantages Over an 8 Hour Roster System (Caporale, Peters and Peters)

Introduction

Health and Safety Factors
1.0 Sleep Disruption and Sleepiness
2.0 Mood
3.0 Stress
4.0 Health
5.0 Fatigue and Performance

Organisational Factors
6.0 Job Satisfaction
7.0 Satisfaction with the 12-hour Schedule
8.0 Union Support
9.0 Organisational Effectiveness

Social and Family Factors
10.0 Social and Family

Summary and Conclusions


Introduction

A growing trend especially in recent years has been the introduction of a 12-hour work roster replacing the traditional 8-hour work schedule. The 12-hour rostering schedule is typically arranged as a compressed work week, which includes, an individual working 2 or 3 days in a row with 2 or 3 days off in a row. Several researchers have outlined the reasons why 12-hour rostering has become popular. For example, Williamson, Gower and Clarke (1994) identified that one of the main reasons for implementing a 12-hour shift is to negate the disruptive effects shiftwork has on an employee's health, wellbeing and lifestyle. Rosa (1991) from the National Institute for Occupational Health and Safety in the United States stated that the 12-hour schedules are popular with employees as it allows more time, via extra days off, to recuperate from the nightshift; it increases time spent with family and friends and allows more time for other recreational pursuits. One of the main concerns with implementing a 12-hour roster is the effect it has upon employee's levels of fatigue which could then lead to health or safety hazards, as well as reduce productivity, and increase turnover and absenteeism (Rosa & Bonnet, 1993). The aim of this executive review is to examine more closely the advantages and disadvantages of 12-hour rostering especially with regard to health and safety, organisational effectiveness, as well as its impact on family and social life.


Health and Safety Factors

1.0 Sleep Disruption and Sleepiness
One of the most common problems experienced as a result of shift work is sleep disruption which may consequently affect sleeping patterns more generally and sleepiness at work. Rosa (1991) examined sleep disruption in control room operators and found that 12-hour shifts produced a 1 to 3 hour reduction in sleep over a 3.5 year period. Sleepiness increased during both the 8-hour and 12-hour shift but there was a greater increase in sleepiness during the 12-hour shift. However, an important finding was that there was a day-to-day recovery from working the twelve hour shifts, indicating greater recuperation during the worker's days off. Employees also noted that as a consequence of the 12-hour roster, more awakenings during their sleeping period occurred despite more frequent napping. The 12-hour roster produced longer sleep periods after a day shift or a rest day, but there was a reduction in sleep length following a 12-hour night shift. Despite the feelings of sleepiness Williamson, Gower and Clarke (1994) state that 12-hour rostering actually reduced feelings of tiredness throughout the work week. Other affects of 12-hour rostering in relation to tiredness included: decreased amount of time the employees woke up feeling tired; decrease in tiredness during their shift at work and decrease in tiredness after a day or a night shift. Thus, the effect of sleep deprivation day to day may have little affect, but longer periods of time may increase sleepiness that may consequently increase levels of fatigue some employee's may feel.

2.0 Mood
It may be expected that since some workers report feeling sleepier after a 12-hour shift there may be an affect on mood, ie they may be somewhat more tense or sullen. However Williamson, Gower and Clarke (1994) examined computer operators after a 12 month period of 12-hour rostering and the employees felt more clear headed, relaxed and refreshed after the shift finished as compared to employees who had worked the traditional 8-hour shift. Similarily, Duchon, Keran and Smith (1994) from the US Bureau of Mines found that employees after a 12-hour roster were more agreeable, felt more energetic and actually thought more clearly.

3.0 Stress
A particularly important variable when examining rostering is the level of stress experienced by employees. The adverse affects of stress at work may influence health, decision making, performance and the level of absenteeism or turnover. Rosa (1991) in his 3.5 year follow up of control room operators found that stress ratings were lower on 12-hour day shifts, but did increase towards the end of the working week. Pierce and Dunham (1992) examined police officers using physiological and psychological stress symptom measures as well as self report stress scales and found that individuals had a lower level of stress under the 12-hour roster. It is likely that the reduction in stress may be related to the increase in time the employees had with their family and the workers extended periods of rest. Likewise, Walker and Eisenberg (1995) examined patrol officers in Florida and found that officers reported 75% less job stress as a result of a 12-hour shift. It seems conclusive that the 12-hour rostering schedule may reduce job stress.

4.0 Health
The impact of 12-hour rostering upon other general health variables has been examined by Williamson, Gower and Clarke (1991). The authors used a questionnaire to examine health symptoms as well as the General Health Questionnaire (GHQ) to establish the employees mental health status. They found that there was a lower incidence of symptoms including: loss of appetite; constipation; diarrhoea; upset stomach; shortness of breath; unusual heart rate; headaches, and feeling faint after a 7 month period on the 12-hour roster. There was an actual improvement in physical health reported especially with gastrointestinal problems. Supporting the comments made above, they found from an anlaysis of the GHQ, that fewer employees were psychologically distressed after the implementation of the 12-hour roster.

5.0 Fatigue and Performance
One of the most examined variables in studies comparing the 12-hour to the 8-hour roster has been the 12-hour roster's effect upon fatigue and consequently performance. Conflicting reports in the past have sugested that the 12-hour roster may or may not influence fatigue or performance. Baker, Olson and Morisseau (1994) more recently have argued that the 12-hour roster may have positive consequences. For example, it may be safer to have employees work in order to finish a significant task. Here the authors argue that the 12-hour shift can reduce the number of shift turnovers which decreases the potential for error and may offset any potential error resulting from fatigue. The results highlighted that the 12-hour shift caused less operator fatigue than high levels of overtime during the 8-hour schedule. Only 1 out of 6 possible breaches in safety measures was found to be associated with the 12-hour shift in contrast to 6 out of 6 breaches in safety measures being associated with high overtime levels. The authors concluded that problems with the 12-hour shift may only occur with poorly defined or implemented schedules. Previously, Pierce and Dunham (1992) similarily reported that the implementation of a 12-hour roster actally reduced fatigue levels. One explanation for this effect may be that on a 12-hour roster the workers have extended sleep periods during their days off. In contrast, Rosa (1991) studied the long term effects of the 12-hour scheduling using a fatigue battery test. The results indicated that grammatical reasoning reaction time and auditory reaction time was slower after a 7 month and a 3.5 year period. Interestingly, there was no deterioration in performance or alertness during the week suggesting a day to day recover. Rosa and Colligan (1992) found a decline in performance and alertness by 50% after a 12-hour shift. This occurred especially during the end off the nightshift when extended work hours in combination with a decrease in the body's arousal (due to the circadian rhythm) produced greater fatigue. In this study they also found that the worker's fatigue level was also influenced by the high physical demands of the work. The authors suggest that hazardous activities should be scheduled early in the shift if possible. In contrast, Duchon, Keran and Smith (1994) used fatigue sensitive behavioural and physiological performance measures which showed no change or improvement with 12-hour shifts, concluding that 12-hour shifts do not pose a hazard with respect to occupational health or safety. Safety remains for everyone a central issue. Several studies have examined the error rate associated with 12-hour rostering. For example, Williamson, Gower and Clarke (1994) found that computer operator errors per hour did not differ between the two different schedules. However, total system errors per hour increased with the new 12-hour roster. In a comprehensive study Rosa and Bonnet (1993) issued a computerised test battery designed to evaluate a range of psychological functions including cognitive, perceptual and motor skills. Here the authors found more simple reaction time misses during the 12-hour schedule. However, there was no difference in grammatical reasoning errors, digit additions and total errors. Likewise, Duchon, Keran and Smith (1994) examined employees working at an underground mine. The results indicated that there was a decrease in tapping speed but this did not indicate a health or safety risk during a 12-hour shift. There was no difference in maximum aerobic capacity and heart rate recovery indicating no physically fatiguing effects of a 12-hour shift.


Organisational Factors

6.0 Job Satisfaction
Several recent studies have examined the question of job satisfaction and it has been found that job satisfaction improves under the 12-hour schedule ( Pierce and Dunham, 1992). However, Bernreuter and Sullivan (1995) who examined shift length variations in nurses found that job satisfaction did not improve, but these results should be viewed with caution as a small sample size was used and the adequacy of the instrumentation was unknown. In contrast, Williamson, Gower and Clarke (1994) stated that there were no changes in job satisfaction, however, there was a trend towards a more favourable response to the question "how satisfied are you with your job?".

7.0 Satisfaction with the 12-hour Schedule
There is overwhelming evidence suggesting that the employee's satisfaction with the 12-hour schedule is high. For example, Rosa and Bonnet (1993) examined employee's attitudes towards the 12-hour schedule at a natural gas utility. The results indicate that more than 80% of the employees voted to retain the new work schedule. An important finding was also that the employees were happy to tolerate the increased fatigue levels to keep the schedule. Similarly, Duchon, Keran and Smith (1994) examined 31 employees in an underground mine working an 8-hour shift. Thirty eight percent of the employees stated that the main reason they would change jobs is to work different hours. Eighty percent of the 12-hour shift workers reported that they prefer working a 12-hour shift. Likewise, Walker and Eisenberg (1995) reported that 65% of the deputies reported in favour of the conversion to the 12-hour schedule.

8.0 Union Support
As it presently stands the Australian Council of Trade Unions (ACTU) now recognises that a correctly designed 12-hour roster can be beneficial to the employee, especially in increasing leisure time. In 1988 the ACTU adopted a Code of Conduct on Twelve Hour Shifts which states that the implementation of the 12-hour shift should only be done where: continuous work processes or special circumstance warrant it's introduction; the introduction of the 12-hour shift will not produce excessive mental or physical strain; a proper examination of the health risks and demonstrated benefits of the 12-hour schedule can be conducted; after consultation with the union; two thirds of the workers accept the 12-hour shift, and the possibility that the 12-hour schedule will generally reduce working time. The code of conduct also lays down various control measures including the development of the shift roster, award variations and administrative measures to further reinforce health and safety standards (ACTU, 1988, cited in Mathews, 1993). Since the increase in the popularity of 12-hour shifts, unions in Australia have seen a need to take a position in relation to what they regard are the occupational health and safety standards to guard against any potential problems. Mathews (1993), outlining the Code of Conduct on Tweleve Hour Shifts stated that, "while 12-hour shifts are not hazardous in themselves, they potentially exacerbate the problems of shift working..." (p. 318). However, Mathews (1993) writing in a rather authoritative style, outlining the potential negative affects of twelve hour rostering, failed to include current literature to support the position of the ACTU. The preponderance of current literature seemingly suggest that 12-hour shifts actually improves health, and reduces psychophysiological distress. Mathews (1993) could have been more rigorous in his approach. For instance, his use of the notion "exacerbation" is not supported by current theory or practice. While the text, published in 1993, is often used by unions to argue against 12-hour rostering, a closer scrutiny of his references, shows he has not based his opinion on any recent articles from reputable journals, but rather, more from seminars, proceedings and symposiums presented mostly during the 1980's. It would seem that some of the issues concerning the health and welfare of workers may have become lost in industrial debate which is seemingly couched in politics rather than health, as evidence in this review so far would seem to indicate.

9.0 Organisational Effectiveness
The contribution that the 12-hour roster provides towards organisational effectiveness is difficult to measure. The variables which have been examined in many studies include: motivation, turnover, absenteeism and cost. For example, Pierce and Dunham (1992) found that organisational effectiveness improved, but general work attitudes remained unchanged. There were no changes in organisational commitment, job involvement or intrinsic motivation. These results are probably due to the shift schedule being one of many factors which may influence these work related attitudes. However, Walker and Eisenberg (1995) reported that 83% of the deputies reported an increase in productivity after the implementation of a 12-hour schedule. Likewise, Duchon, Keran and Smith (1994) reported positive effects upon absenteeism and morale in survey responses. In their study 80% reported that the new 12-hour schedule increased morale and 100% of subjects indicated that absences either decreased or stayed the same. Rosa (1993) emphasised the effectiveness that the 12-hour schedule provides, especially through management's eyes. Management, he said, believes in the popularity of the work schedule because it may reduce attrition. Thus the retention of experienced workers is considered advantageous as this can reduce training costs and this, in turn, may increase safety and efficiency.


Social and Family Factors

10.0 Social and Family
One of the assumptions made about the 12-hour shift is that it allows for employees to interact more satisfactorily with their families and community groups. Research supports this conclusion, for example deputies which followed a rigid 8-hour schedule found it to be too inflexible, and in particular it did not allow for appropriate adjustment to personal and family needs. Once the new 12-hour schedule was operational the employees stated that it had a positive affect upon their family and social lives (Walker and Eisenberg, 1995). Likewise, Pierce and Dunham (1992) found that shift work increased the quality and quantity of workers contact with their families and friends. The 12-hour schedule organised as a compressed work week increased life satisfaction, leisure time and allowed for a more harmonious period with their family.


Summary and Conclusions

Table 1. Advantages and Disadvantages of 12-Hour Rostering.

Advantages
Sleep Disruption and Sleepiness. Day to day recovery. Reduced feelings of tiredness throughout the work week.
Mood. Clear headed, relaxed and refreshed.
Stress. Lower levels of stress reported.
Health. Lower incidence of symptoms (loss of appetite; constipation, diarrhoea, upset stomach; shortness of breath, heart rate; faintness). Fewer gastrointestinal problems.Less Psychological Distress.
Safety and Performance. Decreases the need for shift turnovers increasing safety. Decreased number of individual errors per hour.
Fatigue. May reduce fatigue levels. Day to day recovery from fatigue.
Job Satisfaction. Increased job satisfaction.
12-Hour Schedule Satisfaction. Increased satisfaction with the 12-hour Schedule.
Union Support. Supported by the unions if the schedule is in line with the ACTU Code of Conduct on Twelve Hour Shift Work, 1988.
Organisational Effectiveness. Improved or no changes in work motivation; turnover, absenteeism or cost.
Social and Family. Increased satisfaction with family and social contact.
Disadvantages
Sleep Disruption and Sleepiness. Long term sleep reduction by 1-3 hrs per period over a 3.5 year may occur.
Fatigue and Performance. Alertness and performance may be lower. Slower reaction times and an increase in the total number of system errors may also be evident. *

* However, this is also evident in the context of rotating rosters where employees work extended shifts, ie "doublers", when the problem of fatigue and performance decrements may be even more significant.

From a review of the more recent literature there seems to a be a number of positive effects associated with 12-hour rostering. Table 1 outlines the advantages and disadvantages associated with introducing a 12-hour roster in relation to health and safety, organisational effectiveness and social and family factors. Overall, 12-hour shift work is seen to have many advantages and this conclusion is based on the following evidence:

(1) the work force overwhelmingly supports the implementation of the 12-hour schedule

(2) generally, research indicates positive effects upon health, mood, stress, organisational effectiveness, and family and social contact. Some authors reported disadvantages with the 12-hour schedule (see table 1). In some cases it has been found that 12-hour rostering may lead to additional fatigue which can in turn lead to reductions in performance, especially in the long term. However, research has not indicated that this leads to any breaches in safety. Finally, before implementing a 12-hour roster or for that matter any shiftwork roster, to consider,

(1) the issues involved in relation to job design, complexity of the task and safety issues.

(2) recognise individual differences in worker's needs.

(3) develop appropriately developed compressed work week schedules (traditionally with 3 to 4 days on with 3 to 4 days off).

(4) periodical evaluation of any affects of the 12-hour shifts.


References

Baker, K., Olson, J., and Morrisseau, D. (1994). Work Practices, fatigue, and nuclear power plant safety performance. Human Factors, 36(2), 244-257.

Bernreuter, M., and Sullivan, M. (1995). Survey and critique of studies related to shift length variations in nursing from 1970 to 1993. International Journal of Nursing Studies, 32(2), 188-197.

Duchon, J.C., Keran, C.M., and Smith, T.J. (1994). Extended workdays in an underground mine: A work performance analysis. Human Factors, 36(2), 258-268.

Mathews, J. (1993). Health and Safety at work: A trade union safety representatives handbook. (2nd ed.).Sydney: Pluto Press.

Monk, T.H., and Folkard, S. (1992). Making shiftwork tolerable. England: Taylor and Francis.

Peters, R.F. (1996). 12 Hour Rostering: A short Seminar for Mt Owen Mine, Singleton, December.

Pierce, J.L., and Dunham, R.B. (1992). The 12-hour work day: A 48-hour, eight-day week. Academy of Management Journal, 35(5), 1086-1098.

Rosa, R. (1991). Performance, alertness and sleep after 3.5 years of 12 h shifts: A follow up study. Work & Stress, 5(2), 107-116.

Rosa, R., and Bonnet, M.H. (1993). Performance and alertness on 8 h and 12 h rotating shifts at a natural gas utility. Ergonomics, 36(10), 1177-1193.

Rosa, R., and Colligan, M.J. (1992). Application of a portable test battery in the assessment of fatigue in laboratory and worksite studies of 12-hour shifts. Scandinavian Journal of Work and Environmental Health, 18(2), 113-115.

Walker, R.B., and Eisenberg, C. (1995). The 12-hour, fixed shift: measuring satisfaction. The FBI Law Enforcement Bulletin, 64(8), 18-21.

Williamson, A.M., Gower, C.G.I., and Clarke, B.C. (1994). Changing the hours of shiftwork: A comparison of 8- and 12-hour shift rosters in a group of computer operators. Ergonomics, 37(2), 287-298.

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