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Within the last few years an increasing number of work places have opted to change their shift work from 8 to 12 hour shifts. The shift employees generally prefer the longer 12 hour shifts as it provides them with more days off per month. Many questions have been raised in relation to the effects the longer shifts will have on the workers' performance during the shifts. Human factors research is beginning to answer some of the questions management often struggles with when deciding to switch to the longer shifts. A recent study by R.M. Anderson and D.A. Bremer (Human Factors, 1997, 29(4)) investigated the relation between sleeping patterns at home and sleepiness on the job for 12 hour shift workers. The report looked at workers who fell asleep quickly, workers who had trouble falling asleep, and their duration of sleep in relation to their reported sleepiness during their 12 hour shifts. No differences of sleepiness on the job existed between the workers who fell asleep quickly and those who didn't. However, the reported sleepiness on the job of the short sleepers was significantly less than for those workers who slept for the longer periods on both day and night shifts. The difference was explained in terms of a hypothesized effect of long sleeping on circadian rhythms. In short, the longer sleep periods would obscure the sleeper's time of day cues, not allowing the establishment of the circadian rhythms.

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This year's Fall meeting for the Center for Operator Performance will be October 7-10 in Houston, TX. For more information, please contact Lisa Via. Guests are always welcome!


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David Strobhar's book, "Human Factors in Process Plant Operation," is now available in both hardcover and Kindle e-book.

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