Author: Wener, Richard
Date published: March 1, 2010
The use and management of shift work is worthy of close attention, for the benefit of the efficiency and productivity of the workplace and for the health and well-being of workers. Sleep-related problems are common in American workers, and even more so among men 30-60 (Millman et al., 1991; National Commission on Sleep Disorders Research, 1992; Webb, 1995; Young et al., 1993). Shift work adds significantly to these problems. There is ample evidence from many kinds of shift work settings (such as factory workers, firefighters, medical residents and nurses, as well as correctional officers) that shift work is often connected to sleep difficulties and disorders. In turn, these sleep problems lead to short term and chronic health issues as well as difficulties on the job- 60% to 80% of shift workers show sleep disorders (Leger, 1994; Rosen, 1996). It also seems clear that the way shift work is managed can limit or mitigate some of these problems.
Shift work leads to difficulties in both the quantity and quality of sleep. Shift workers are likely to sleep for fewer hours during periods when they are on work shifts for times other than their biological daytime, and have poorer, less restful sleep. Sleep hours can be reduced or become fragmented. Recovery from lost sleep is not quick and can take more than one night of longer sleep (Gordon et al., 1986; Van Dongen et al., 2003). These sleep difficulties have a number of serious consequences.
Physical Health Effects
Knutsson (2003) suggests that shift work leads to disease through multiple pathways. Disruption of normal daily rhythms (circadian rhythms defined below) increases susceptibility to diseases directly and by disrupting normal sleep. It also leads to changes in behavioral patterns, such as increased smoking, poorer diet, and reduced exercise, in part because of increased stress and social disruptions. Shift workers are more likely to suffer from marital and family problems. All of these patterns (smoking, diet, reduced exercise) have been related to increased likelihood of illness.
Because of these changes in healthful patterns of living, and other problems related to lack of sleep (hypertension, diabetes, increased cholesterol levels), sleep problems have been shown to lead to increased incidence of cardiovascular disease, and shift workers may have as much as 40% increase in risk of CVD (Boggild & Knutsson, 1999).
In addition, shift work and sleep disorders have been related to increases in gastrointestinal and metabolic disorders, at least in part because of digestive responses to eating meals at biologically odd hours (Costa, 1996). Shift work has also been associated with cluster headaches (Beck, Sieber, & Trejo, 2005).
The fatigue and reduced level of alertness that comes along with sleep problems and working during biological night have other mental and behavioral effects. Mental alertness and cognitive process are made less effective, leading to reduced productivity and, in the case of correctional institutions, increased chances of missing critical events or behaviors. Shift work is associated with an increased rate of accidents on the job, and even more common, accidents driving home from work at the end of a long, late shift. In addition, irritability is increased and inhibitions can be reduced during sleep deprivation (Folkard, Lombard, & Tucker, 2005). People working during sleep deprivation are likely to have incidents of "micro-sleep" - unnoticed (even by themselves) periods of very brief sleep or nodding off (Swenson, Waseleski, & Hard, 2008).
Reduced mental alertness, lower levels of working memory capacity, and lessened cognitive abilities are reflected in poorer performance with respect to self regulation, self control, and risk assessment, poorer judgment, increased impulsiveness, poorer reasoning skills, and more "sloppy" behavior on the job (Alhola, & Polo-Kantola, 2007; Kimberg, D'Esposito, & Farah, 1998).
These problems also have additional implications for organizations. Sleep problems from shift work have been related to increased absenteeism and rates of staff turnover and greater use of sick time (Caruso et al., 2004). Because of these absences, what often results are an increased use of overtime and greater use of less experienced staff to cover for absences.
Mechanisms - How Shift Work Leads to Problems
Shift work (like jet lag) affects circadian rhythms. "Circadian," in Latin, literally means "about one day" and refers to the various cycles of a living organism that function on or are somehow related to the 24-hour cycle of a day (http://en.wikipedia.org/wiki/ Circadian _rhythm).
These rhythms are sensitive to patterns of light and dark and can be adjusted or reset to some degree by exposure to lighting - especially high intensity daylight. High intensity lights are used clinically in this manner to reduce jet lag or as therapy for seasonal affective disorders, a form of depression that increases during winter months when we experience reduced levels of light.
Human performance is most seriously affected when people are awake and working during hours of their biological night, and the impact is most detrimental in the hours before normal waking (Barger et al., 2009).
Managing Shift Work
All 24-hour institutions must address shift work. The question is not whether to have shifts, but how best to manage them and in what ways can one ameliorate the negative effects - both for the workers and for the organizations. One approach is to address the nature of the shifts themselves - length, time on shift, timing, time between rotation schedule. Others include providing training in ways to manage time and recognize symptoms of sleep disorders and providing professional support to deal with problems as they arise.
Length of shifts. Extended shifts for medical interns have long been seen as hazardous to work performance. Workers on shifts of 12 hours or longer, when combined with schedules that have more than 40 hours of total work per week, show increased fatigue; reduction in alertness, cognitive functioning, and performance on vigilance tasks; and increases in level of injuries and health complaints (Caruso et al., 2004). One study of nurses found no differences in performance between 12- and 18-hour shifts with respect to cognitive ability provided the subjects were able to get adequate (7 hours) sleep (Thomas et al, 2006).
The U.S. Navy has traditionally used 6-hour shifts for seamen (6 hours on duty, 6 hours on other assignment, 6 hours sleep), creating effectively an 18-hour work day. Recent research has indicated, however, that these 18-hour days lead to more problems in fatigue and performance than schedules that synchronize with the biological 24-hour day. Because of this research, the Navy is considering abandoning their traditional schedule for one based on eight-hour shifts (Crepeau, Steele, & Duplessis, 2006).
In industrial settings, longer shifts, whether from regular schedules or overtime, have led to much higher accident and injury rates. 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 increase (Dembe et al, 2005). There appears to be a linear relationship - as the number of hours that are worked per day increases in regular schedules the rate of injuries rises. There is also a higher risk of accidents during night shifts, and one study found 10-hour shifts had 13'M) increased injury risk than 8-hour shifts, with 12-hour shifts having a 27% greater risk of injury. (Folkhard, Lombari, & Tucker, 2005). Many workers claim their social and domestic life is better with 12-hour shifts; however, performance declines compared to 8-hour shifts (Mitchell & Williamson 2000).
Time between shifts. Recent research suggests the time available to workers between shifts may be important in order to get necessary amounts of sleep. Nurses working with less than 16 hours between shifts got less than their required amount of sleep. The authors recommend 16 hours as a minimal time between shifts. (Kurumatani et al., 1994).
Direction of shift rotation. Workers adjust more easily to shift changes when their schedule allows them to shift in a forward clockwise direction, (day then evening, then night) than when changing shifts counterclockwise (Knauth, 1995).
Speed of rotation. Very brief periods on shifts (several days at a time) result in no break in circadian rhythms but are very difficult for workers to endure. Shift periods of several weeks also provide little ability to adjust circadian rhythms to time changes, causing continual disruptions in sleep patterns. Slow changes in shifts (several months or more) allow for circadian patterns to adjust and change, although some argue that for many total adjustment is never made, leading to long term negative effects (Knauth, 1995).
Breaks during shifts. Studies suggest that frequent short breaks during overnight shifts are more effective than one long break in increasing levels of alertness. "The severity of the effects from shift work stress is directly related to the recovery time necessary to onset those effects" (Swenson, Waseleski, & Hard, 2008, p. 305).
Training. Several researchers have suggested that one can reduce negative effects of shift work by providing training for staff members in a number of areas such as ways to enhance sleep, safety procedures, family issues, and when and how to recognize sleep disorders and seek professional help. One study suggested that staff turnover rates can be substantially reduced by implementation of such programs (Swenson, Waseleski, & Hard, 2008). Medical professionals suggest that institutions that depend on shift work set up programs for identifying and seeking treatment for sleep problems. This can include treatment of accompanying problems, including marital and family issues.
People can also learn better ways to make use of caffeine, such as in coffee, to reduce sleepiness and increase alertness (Muehlbach & Walsh, 1995). In particular, recent research has found that, rather than drinking large amounts of coffee at one time "high-frequency, low-dose caffeine administration is effective in countering the detrimental performance effects of extended wakefulness" (Wyatt et al., 2004.)
Regulation of overtime. Accidents, especially while driving home from a shift, are a serious concern when staff members are drowsy from overnight shifts or significant overtime. Managers need to note the amount of overtime and condition of staff leaving the institution. "A key issue with 12-hour shift systems and the potential for increased fatigue and reduced alertness is the regulation of overtime" (Baulk et al, 2008, p. 697). They suggest that overtime be controlled to keep employees from overextending their periods of wakefulness, or at least to add monitoring and safeguards for human error. "Most regulated systems specify that no longer than 4 hours of additional work be added to any 12-hour shift, and also that a minimum period of 8-10 hours of rest break be taken following any period of extended work" (Baulk et al., 2008, p. 697).
Others suggest that, where possible, staff should avoid especially risky duties in the hours before normal biological waking (3-5 a.m.) and do things to increase alertness "such as conversations, walking about or exercising, having healthy snacks, or going into brightly lit areas"(Swenson, Waseleski, & Hard, 2008, p. 305).
Physical conditions. Circadian rhythms respond to levels of light and dark. Providing high intensity lighting (1000 lux or greater) in the workplace can help reduce sleepiness. It may be just as important to assure darkness at home for sleeping with drapes, eye masks, etc. (Burgess, Sharkey, & Eastman, 2002).
Editor's Note: This article was provided by ProQuest Information and Learning Company. All rights reserved. It was reprinted and adapted with permission from © copyright National Sheriffs' Association, January 2009.
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Richard Wener, Ph.D., is a professor of psychology at Polytechnic Institute of NYU. He may be contacted at Polytechnic via e-mail at firstname.lastname@example.org.
The jail staffing series has been developed for the National Sheriffs' Association by Rod Miller and John Wetzel, two of the authors of the upcoming 3rd Edition NIC Jail Staffing Analysis Handbook. For more information, contact email@example.com, CRS Inc., 925 Johnson Drive, Gettysburg, PA 17325, or 717-338-9100, or John Wetzel, Warden, Franklin County Jail, 1804 Opportunity Avenue, Chambersburg, PA 17201, 717-264-9513, jewetzel@ co.franklin.pa.us.