Shift-work stress impedes health, performance
Hospitals may ignore potential risk factor
Shift work is so commonly taken for granted in hospitals that it usually is overlooked as a cause of stress for health care workers, but in fact it is a risk factor for illness and injury, says Susan E. Labyak, PhD, RN, research fellow at the Center for Circadian Biology and Medicine of Northwestern University in Evanston, IL.
Although the possible harmful occupational effects of shift work are being researched by other industries, the absence of hospital worker studies seems to indicate a lack of concern, Labyak notes.
"People in industry are increasingly interested in this, especially when you start flashing around a dollar figure of how much accidents cost," she says. "The research done on shift work has been largely in industry. There are no good hospital studies. Hospitals usually don't have consultants come in and design [safer] shift work."
According to Labyak and other researchers, shift workers experience three main sources of stress:
* disruption of circadian rhythms;
* disruption of sleep, with resulting fatigue;
* social and domestic disturbances.1
Shift work can have two consequences related to circadian rhythms or sleep cycle. First, some shifts might require an employee to be awake and active at an inappropriate time during the circadian cycle. Second, certain schedules cause a person's circadian rhythms to be out of synchrony.
Labyak explains that a person's body temperature peaks in the evenings and falls during the night.
"The time we usually become sleepy and fall asleep is when our temperature has fallen at night. We wake up as our temperature rises in the morning. When we put people on shift work or jet-lag them from flying across multiple time zones, then suddenly your sleep is out of phase with your temperature. You go through a period of time when you have to adjust, and that's when your sleep is of a very poor quality because you're sleeping at a time when your temperature is high. Essentially, you're sleeping at a time when you would be working and working at a time when you would be sleeping, which is out of sync," she says.
Alertness rhythms follow temperature rhythms, she adds. Most people's temperature is lowest around 3 a.m., which is the time they are most sleepy and therefore least alert.
Sleep disruption and fatigue
Studies show that about 60% to 70% of workers on rotating shifts complain of sleep disruption.2 Sleepiness is more common among night shift workers than workers on other shifts, and the most common complaint is the inability to get enough sleep during the day.3
Sleep disruption can result from "endogenous factors [which] stem from the desynchronized circadian system," or from "exogenous factors," such as daylight in sleeping quarters, household noises (telephone ringing, television playing, general activity) or outdoor noises (traffic, children playing). Other disruptions include domestic commitments, such as shopping and child care.1
Lack of sufficient sleep results in chronic fatigue and sleepiness.4
Shift work can also create stress by preventing workers from fulfilling important family roles.5 Partner and parenting relationships can suffer, causing marital problems and social alienation. A study of married couples showed that shift work is associated with lower-quality family time and more frequent family conflicts.6 Another study revealed an almost 50% increase in divorces and separations among night-shift workers over workers on day and evening shifts.7
Shift workers also face stressful social problems because society is geared toward a daytime work schedule. Researchers note that shift workers feel alienated from the community because they are unable to attend most recreational events, religious and educational meetings, and social clubs.5
Although the consequences of these three main stressors vary among individuals according to personality, sleep habits, and age, shift workers often experience negative health effects resulting from chronic, repeated exposure to stressors.1
Surveys show that shift workers suffer general health complaints in greater proportions than day workers. Rotating shift workers in particular have a higher incidence of sick leave, a higher rate of worksite clinic visits, and poorer scores on various health indexes.8,9
In addition to sleep disturbances, adverse signs and symptoms associated with shift work include fatigue, muscle aches, general malaise, irritability, respiratory infections, and gastrointestinal upsets, says Labyak, who also is launching a study of nurses to determine if shift work is associated with menstrual irregularities and miscarriage.
The link between shift work and gastrointestinal disorders is well-established. Night shift workers in particular complain of general gastric discomfort and peptic ulcer disease.8, 10-11
Beyond specific health problems, adverse effects of shift work are diffuse, affecting some workers' general sense of well-being. They report increased feelings of irritation and strain, increased use of alcohol and drugs, and a general malaise that may be exacerbated by the psychological stress of less domestic and social satisfaction.1
Task performance negatively affected
Job performance can be directly affected by circadian desynchronization, with fatigue and sleep deprivation clearly having a negative effect on the performance of most tasks.12,13
A survey of nurse supervisors found that the job performance of nurses on rotating shifts was lower than for those on fixed day, afternoon, or night shifts.14
To help counteract the stressful effects of shift work, Labyak suggests putting employees on permanent shifts whenever possible.
"This is good because people can plan their lives around [their shift] and get into a routine," she says.
Another possible solution is use of a "chronobiotic agent" to quickly shift the internal clock of workers on night shifts. This involves the use of interventions such as very bright light (at least 2,000 lux) in the workplace.
Also, if workers must rotate shifts, she advises rotations in a "clockwise direction," from day shift to evening shift to night shift. "This is a more natural direction for us," she says.
More studies are needed to record 24-hour real-task data in the field to determine whether night shift workers demonstrate decreased job performance, Labyak says, adding that occupational health practitioners are ideally positioned to conduct this kind of research.
Labyak suggests using accident reports and a computer to track specific times at which accidents occur, the worker's shift schedule, and the worker's health history. The latter already would be obtained at preplacement and annual physical assessments.
"This is a rich database that we have yet to tap into to attempt to answer many longitudinal questions about shift work," she says.
References
1. U.S. Congress, Office of Technology Assessment. Biological Rhythms: Implications for the Worker. OTA-BA-463. Washington, DC: U.S. Government Printing Office; September 1991.
2. Rutenfranz J, Haider M, Koller M. "Occupational health measures for night workers and shift workers." In: Folkard S, Monk TH, eds. Hours of Work: Temporal Factors in Work Scheduling. New York City: John Wiley & Sons; 1985.
3. Akerstedt T. A questionnaire study of sleep/wake disturbances and irregular work hours. Sleep Research 1983; 12:358.
4. Akerstedt T. Sleepiness as a consequence of shift work. Sleep 1988; 11:17-34.
5. Walker J. "Social problems of shift work." In: Folkard S, Monk TH, eds. Hours of Work: Temporal Factors in Work Scheduling. New York City: John Wiley & Sons; 1985.
6. Staines GL, Pleck JH. The Impact of Work Schedules on the Family. Ann Arbor, MI: University of Michigan Institute for Social Research; 1983.
7. Tepas DI, Armstrong DR, Carlson ML, et al. Changing industry to continuous operations: Different strokes for different plants. Behavior Research Methods, Instruments, and Computers 1985; 17:670-676.
8. Moore-Ede MC, Richardson, GS. Medical implications of shift work. Annual Rev Med 1985; 36:607-617.
9. Ottman W, Karvonen MJ, Schmidt KH et al. Subjective health status of day and shift working policemen. Ergonomics 1989; 32:847-854.
10. Baker D. The use and consequences of shift work. Int J Health Services 1980; 10:405-420.
11. Rutenfranz J, Colquhoun WP, Knauth P, et al. Biomedical and psychosocial aspects of shift work: A review. Scand J Work Environ Health 1977; 3:165-182.
12. Colligan MJ. "Shift work: Health and performance effects." In: Rom WN, ed. Environmental and Occupational Medicine. Boston: Little, Brown; 1983.
13. Krueger GP. Sustained work, fatigue, sleep loss and performance: A review of the issues. Work and Stress 1989; 3:129-141.
14. Coffey LC, Skipper JK, Jung FD. Nurses and shift work: Effects on job performance and job-related stress. J Adv Nursing 1988; 13:245-254. *
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