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Fixed Versus Rotating Shifts


One of the most challenging questions in shift work schedule design is whether to rotate crews or keep them fixed. With a rotating schedule, employees' scheduled shifts change periodically. Under a fixed schedule, employees' work hours are the same every workday.

From an employer's point of view, rotation provides the advantages of balancing skills and experience across all shifts, and of providing all employees with equal exposure to daytime management, training, HR support, suppliers, and other key daytime personnel.

From the employees' point of view, fixed schedules provide stable work hours, making it easier for them to organize their lives. Fixed shifts may also be related to less sleep disruption and fatigue, at least for the day shift personnel.

However, workers on fixed night shifts may end up even more fatigued than workers on rotating shifts because they almost invariably switch back to a daytime schedule on their days off to pursue social activities with their families and friends.  This essentially creates a fast, defacto rotation.  Fixed evening shifts may also have a substantial negative impact on family and social life.  All of these factors create difficulties in balancing the mix of skills, qualifications, and experience across each of the crews and thus imbalances in productivity.  They also pose significant communication challenges for management.

There is still a lack of conclusive data on the effects of fixed versus rotating shifts on alertness, performance, and accidents. Studies comparing workers on fixed and rotating shifts often find that the groups are not similar regarding age, marital status, freedom to choose the shift, or type of task performed or sleep management. Some studies have found that permanent night workers sleep less and have a higher prevalence of fatigue than rotating shift workers (Tepas and Carvalhais 1990, Alfredsson et al. 1991). However, some researchers have described a lower accident rate, a higher rate of performance, and a lower rating of effort in permanent night workers as compared to rotating shiftworkers (Gold et al. 1992, Totterdell et al. 1995).  Certainly, the type of shift pattern also presents a confounding effect on these studies.
Other authors have noted that individuals who are "owls" (i.e. night types, who tend to go to bed late and get up late) adjust more easily to nightwork. There are a number of studies evaluating methods, such as bright light, to improve the adjustment to night work, but there is still much work needed (Rosa et al. 1990).  In the final analysis, the decision on rotating vs. fixed shifts may best be left to the employees themselves, since “ownership” may again be the key factor to adaptation and thus optimal performance.


Tepas DI, Carvalhais AB. Sleep patterns of shiftworkers. Occup. Med. 5, 199-208. 1990.

Alfredson L, Akerstedt T, Mattson M, Wilborg B. Self-reported health and well-being amongst night security guards: a comparison with the working population. Ergonomics 34, 525-530. 1991.

Gold DR, et al. Rotating shiftwork, sleep and accidents related to sleepiness in hospital nurses. Am. J. Publ. Health. 82, 1011-1014. 1992.

Totterdell P, Spelten E, Smith L, Barton J, Folkard S. Recovery from work shifts: how long does it take? J. Applied Psychol. 80 (1), 43-57. 1995.

Rosa RR et al. Intervention factors for promoting adjustment to nightwork and shiftwork. In: Shiftwork. AJ Scott (Ed.) Occupational Medicine 5(2), 391-416. 1990.

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