Jan 20, 2008

Shiftwork schedule factors: work-rest ratios and predictability

As part of our continuing discussion of shiftwork scheduling factors, today we're talking about time on the job compared to time off. We'll also discuss the predictability of the schedule. A fixed or regularly rotating schedule may be daunting at times but an unpredictable schedule, such as those worked traditionally on the railroads takes an even greater toll.

The more a person works, the less time he or she will have for rest. People who work an 8-hour shift will have 16 hours left in a day to do everything else, and also to get some rest. People who work a 12-hour shift have only 12 hours to do everything else and to rest. In a situation like this, the extra work hours mean more tiredness and less time for rest.

This is a two-edged sword. For example, many times a worker's home responsibilities, such as taking care of children, cannot change from day to day. So, if workers do overtime or a 12-hour shift, they still must take care of home duties. Since these duties take the same amount of time every day, workers may sacrifice rest and sleep after a long workday.

This example shows us how important the length of shift can be in terms of stress and fatigue.

When looking at work versus rest, we also must consider how many breaks are taken during the shift and the length of breaks. Depending on the type of work and length of the day, several short breaks might be better than a few long breaks. Short breaks might be better particularly for jobs requiring heavy physical labor.

How tired a worker is also depends partly on how many days in a row he or she works. Fatigue builds up over several workdays, as well as over a single workday. This happens especially when a per-son gets less sleep between workdays than on rest days. As we mentioned earlier, a worker might not get enough sleep between long workdays because of home responsibilities. So, if a person works several days in a row, for example, six or seven, a good deal of sleep might be lost. Then the worker feels quite tired during the last one or two shifts.

How Regular or Predictable?
Most jobs have a very regular, set schedule. A worker usually knows the schedule ahead of time. Even if the shift times change, a worker will know several days before-hand. This makes it easy to schedule other non-work activities, such as making sure somebody is at home when the children get there. Other jobs are not so regular or predictable.

For example, health care workers might respond to emergencies that keep them on the job much longer than expected. Or, they might be on call for such emergencies. At a factory, a breakdown or a last-minute call for a product might keep workers at the plant working overtime. Railroad workers sometimes work off a “call board.” This means they can be assigned to a train at the last minute to move a “just-in-time” order of goods.

If workers cannot predict their schedules, it is difficult to get adequate rest. Maybe they just get to sleep when they are called back to work, or maybe they have just worked a long shift when an emergency happens. So, they stay at work a few more hours. Maybe they are on call and never get deep, satisfying sleep because they are always listening for the phone. Some people call this “sleeping with one eye open.”

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