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Shift Work

UE News, February, 1998

More than 15 million U.S. workers perform shift work of some sort; that is, they work regularly outside of normal daylight hours. Some simply work evenings occasionally. But four percent of U.S. workers are permanent night workers, or have irregular work schedules. Still another four percent have the most stressful of work routines of all — rotating shift work.

Many different types of jobs require shift work. Those who take care of hospital patients, the mentally ill or prisoners must perform their services 24 hours a day. Toll collectors, municipal snow emergency workers, and many other public employees, not to speak of police officers and fire fighters, must work or be on call at all hours. In manufacturing plants and service shops, workers often have to work the evening shift. Many drivers of transportation and delivery vehicles have to work evening or late night hours.

All of these work shifts take a toll on human health, according to a recently published NIOSH report ("Plain Language About Shift Work," July 1997). They all result in greater fatigue for shift workers.


"We might think that permanent night workers adapt or get used to their work times," according to the authors Drs. Roger Rosa and Michael Colligan. "However, research tells us that most permanent night workers never really get used to the schedule. Fatigue occurs because most night workers go back to a day schedule on their days off." (My emphasis-D.K.) This is not surprising because family and friends are active during the day. Also many errands and chores, like getting the car fixed, must be done during the day. Because most night workers return to a day schedule they never completely allow their sleep and body rhythms to adapt to being awake at night."

Also, the report notes, night workers sleep less during the day, and sleep less deeply when they do sleep. Thus fatigue can build up over time, resulting eventually in accidents, such as dozing off when operating machinery or driving a vehicle.

But worse than losing sleep is losing contact with others, especially family members, according to surveys of shift workers.

In the long term, shift work appears to cause digestive problems, such as frequently upset stomachs, persistent constipation and sometimes stomach ulcers. Scientists believe this happens because shift work puts a person’s activity schedule out of "sync" with their natural body rhythms (their so-called "circadian" rhythms). These natural rhythms slow down regular body functions at night, when shift workers are working, and speed them up during the day, when they are trying to sleep. This is a good prescription for poor sleep and persistent digestive problems.


Below are some suggestions for reducing shift-work health problems made by the NIOSH report. But as the report says, these should be considered as "suggestions, not as strict guidelines or regulations." They may be useful in a particular job situation, but "all aspects of job and home life must be considered" when changing a work schedule:

  • Avoid quick shift changes. A break of only seven to 10 hours should be avoided before rotating to a new shift, such as going from day to night shift on the same day of the week. A short break means the person may be tired when beginning the next shift, and accidents can result. At least 24 hours of break time are recommended after ending a night-work shift.

  • Try to keep work schedules regular and predictable. It is important to know these well in advance to plan rest, child care and family and other social activities.

  • Re-examine the schedule of rest breaks. Standard lunch and coffee breaks may not be appropriate for your particular job. For example, in Las Vegas, card dealers, who need to concentrate intensely, get 10 to 15 minutes break per hour. For physically demanding jobs, a short break every hour might help fight muscle fatigue. When considering such changes, of course, discuss them first at the local meeting or with the shop health and safety committee, since they can affect everyone.

Revised work schedules which involve 10 to 12 hour work shifts, followed by several days off, are being considered or tried out in some U.S. plants these days. The NIOSH report makes clear that such long shifts, even when followed by long breaks, "can be very fatiguing." While some workers prefer the "mini-vacations" that result, older workers especially may find it difficult to fully recover before starting work again. The result: a long-term build up of fatigue.

(Note: If you would like a copy of this report free of charge, or have questions about it, call the NIOSH hot line at 1-800-35NIOSH [1-800-356-4674]. Again, it’s called "Plain Language About Shift Work," NIOSH Publication Number 97-145)

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