Question: How often should a schedule rotate from day shift to night shift?
Answer: The Speed of rotation - the number of consecutive shifts worked (i.e., morning, evening, night) before changing to a different shift and the amount of time off in between those shift changes – is a controversial scheduling issue.
Shiftwork experts in the U.S. tend to favor slow rotations (e.g. 1-2 weeks day shift, then 1-2 weeks night shift), while European experts prefer quick shift rotations (e.g. daily).
The arguments in favor of quick rotations are as follows (Knauth 1993):
- Quick rotations keep the circadian rhythms in a daytime orientation; that is, theoretically, circadian rhythms are not in a constant state of disruption from switching between day and night work.
- Many consecutive night shifts may cause chronic sleep deprivation, which could lead to long-term health problems
- Shiftworkers have some free evenings every week, allowing them more regular contact with family and friends
The benefits of slow rotations preferred by North American include:
- They usually result in more consistent or regular patterns, allowing workers to better plan their family and social life
- The body adjusts more readily to regularity in schedules (i.e. predictable sleep and eating times)
- Slow rotations reduce the number of sleep/wake transitions between day, evening, and night work
- Most American workplaces use slow rotations and thus American workers are more used to them
That North Americans are more used to slow rotations is illustrated in the Shiftwork Practices Survey of North American plants. Among the facilities reporting 8-hour rotating shifts, the majority (63%) rotated on a weekly basis, 9% rotated on a monthly basis, 11% on a bi-monthly basis, and 17% every set number of days.
For best results, the speed of rotation should be tailored to the specific shift pattern. For example, a 2-2-3 x 12 hour shift rotation is less stressful with a 2 week rotation, than with its customary rotation with every turn (i.e. every 2-3 days). However, with the 3-3 and 4-4 x 12-hour schedules, it is more effective to rotate with every turn to minimize the number of sleep/wake transitions.
Knauth P. The design of shift systems. Ergonomics 36 (1-3), 15-28. 1993.
Aguirre A, Moore-Ede, A. Shiftwork Practices 2007. Circadian Information. 2007.
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