Work Shift Review

The struggle to change night and day circadian rhythms and sleep patterns is familiar to those who have worked night shifts at some time in their career.


The struggle to change night and day circadian rhythms and sleep patterns is familiar to those who have worked night shifts at some time in their career. Accordingly, employers who utilize rotating shifts or fixed night shifts would be well advised to evaluate costs associated with increasing production through these methods as opposed to maximizing machinery output during a standard single shift.

A distinction is made between rotating shift work and fixed night-shift routines, since study findings suggest that shift rotation is more costly than utilizing a fixed night shift. Varieties of rotating shifts include traditional weekly rotations, slower scheduled rotations, two oscillating shifts around a fixed shift, as well as partial-crew shift rotations.

One large study conducted by the National Institute of Occupational Safety and Health [NIOSH Publication No. 2004-143: Overtime and Extended Work Shifts: Recent Findings on Illnesses, Injuries and Health Behaviors] evaluated methods and findings from 52 studies published between 1995 and 2002 to examine the relationship between long work hours and selected health outcomes. The report indicates that the influence of long working hours on health and safety involves a complex interaction of multiple factors, but all studies revealed increased incidence rates. Typical findings demonstrated the occurrence of 1.5 to 2.0 times as many incidents simply due to increased work hours. Similar results were identified with normal hours, but rotating shifts.

Cost quantification related to incident rate includes actual costs consisting of medical expenses, workers’ compensation, plus total claims-administration costs, in addition to some factor for hidden costs, which are generally agreed to be substantially greater than actual costs. The well-known accident iceberg portrays a visible portion of $1 in contrast to the submerged part representing hidden costs in the range of $50 to $60. While hidden costs vary among companies, they include production loss, supervisor and employee time loss, claims processing time, employee replacement costs, and related expenses.

Additional research includes three NIOSH studies indicating an increased auto accident incidence rate associated with shift work or extended work hours. Moreover, a study undertaken by Dr. Joseph LaDou [The Western Journal of Medicine 1982 December; 137(6): 525-530. Health Effects of Shift Work] found that 20 percent of workers are unable to tolerate shift work. That one statistic suggests that merely switching a day crew over to the night shift, or rotating shifts without regard for persons intolerant of shift work or a night-shift routine, entails considerable risk. Clearly, if 20 percent cannot tolerate a night shift, then a significant number of workers would struggle with circadian transition.

Many articles refer to chronic fatigue, the most common symptom among shift workers. Some studies have shown that employees on shift rotation sleep up to four hours less per day than those working fixed shifts. Besides making a person more vulnerable to illness, fatigue can lead to reduced concentration resulting in diminished job performance, as well as reduced attention span, increased reaction time, and thus, errors and accidents.

Various studies measuring fatigue have concluded that memory and logical reasoning were significantly impaired following shift rotation work and schedules regularly consisting of more than 12 hours per day. Other studies examining extended work hours identified as excessive any work beyond 50 hours per week. While research targeting memory and logic capabilities did not quantify costs associated with quality deviations due to chronic fatigue, studies addressing quality issues consistently indicated that fatigue-induced quality problems escalated with shift rotation and extended work hours.

The impact of shift work on quality and performance has been widely researched among health care workers, particularly those subject to nursing shift rotations and ÎmarathonÌ medical-intern stints. All studies reported more frequent mistakes and health care incidents attributed to fatigue. Not surprisingly, perhaps, one Australian study concluded that job performance of older subjects following shift-rotation work was consistently poorer than that of younger subjects.

Another study quantified incidence rates among shift workers as twice that of nonshift workers. The study also showed night-shift personnel, as opposed to rotating-shift personnel, to have only about 10 percent more incidents than day-shift workers. Concomitantly, sick leave almost doubled [Ohayon, N., Lemoine P., Arnaud-Briand V., Dreyfus M., Journal of Psychosomatic Research 2002; 53:577-583. Prevalence and Consequences of Sleep Disorders in a Shift Worker Population].

A review of numerous studies and articles confirms that no research demonstrates a positive correlation between night-shift work and improved worker health and safety. By contrast, cited problems include cardiovascular ailments, decreased hormone production, preterm births, gastrointestinal disorders, increased alcoholism, and higher cancer and mortality rates. Numerous references to greater stress in family relations as well as parental unavailability further emphasize the liabilities associated with rotating- and night-shift work.

Additionally, equipment wear and maintenance problems associated with continuous production cycles are a significant factor in considering nonstop operation of limited-output machinery versus increasing equipment capacity for single-shift production. Though scheduling maintenance into a rotating-schedule work week is possible, sizeable costs are incurred as equipment is maintained while continuous crews remain idle.

These findings suggest to the employer that when production demands warrant extended work hours or rotating shift work, costs associated with maximizing output via shift work or longer hours may be excessive. Those costs are related to an increased workplace incidence rate as well as a higher after-hours auto incidence rate, plus greater employee-health expenses. Such numbers should be considered when funding is evaluated for increasing production-equipment capacity.

Alternatively, the studies indicate that when a 24-hour production rate is unavoidable, employers would reduce costs substantially by establishing a day shift and a separate night shift, as opposed to implementing a rotating-shift schedule. Thus, a night shift comprising employees able to adjust to that routine could be employed; and, theoretically, no persons would be exposed to a continuous struggle in adapting to changing circadian rhythms.

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Effective 12/27/2007, the Department of Transportation’s Federal Motor Carrier Safety Administration (FMCSA) amended the hours of service interim rule, thus allowing commercial motor vehicle drivers up to 11 hours of driving time within a 14-hour, nonextendable window from the start of the workday, following 10 consecutive hours off duty [11-hour limit]. This interim rule was implemented after appellate courts twice struck down the rule.

Its provisions also permit motor carriers and drivers to restart calculations of weekly on-duty time limits after the driver has at least 34 consecutive hours off duty [34-hour restart]. Having solicited public comment, FMCSA announced that it is fully committed to issuing a final rule in 2008.