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Psychological Performance During Sleep Loss and Continuous Mental Work: The Effects of Interjected Naps

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Technical Report

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Defense and Civil Institute of Environmental Medicine Downsview, Ontario Canada

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The need for research and recommendations about sleep logistics planning in sustained operations environments is discussed. The nap literature is reviewed and problems in experimental methodology, cross-study comparability, and generality are noted. To address these problems, a research programme has been initiated in which subjects assume the role of command-post operations officers in conditions anticipated for the sustained-intensive battlefield. The results of experiments from this programme indicate that continuous, intensive mental work combined with 2-3 days of sleep loss leads to greater performance decrements than those found in studies not emphasizing continuous cognitive demands. While the role of various countermeasure, including the effects of physical fitness, physical exercise and cognitive workload have been investigated, none of these interventions reduced the impairment in performance found in this scenario. Two experiments, however, are reported which examine ameliorative effects of short naps on performance. In the first, a 2-hour nap was taken after about 40 hours of wakefulness from 2200-2400h. This nap served to maintain performance the 25-30 pre- to post-midnight downturn in performance typically observed in our continuous work studies was prevented. In a further experiment, a 2-hour nap was taken after about 46 hours of wakefulness from 0400h-0600h. This nap served to recuperate performance the expected post-midnight degradation occurred, but following the nap performance returned to the pre-midnight level. The results are discussed in terms of new strategies for maintaining performance capability during extended work schedules.

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