Abstract
U.S. Navy ship crews are organizationally divided into departments, i.e., functional groups with specific tasks and an officer in charge. The objective of this study is to assess the effect of ship departments on crew sleep patterns and psychomotor vigilance performance. Crewmembers (N=93) from an Arleigh Burke-type destroyer participated in a 16-day quasi-experimental study while the ship was forward deployed. Each sailor wore an actigraph, completed a daily activity log, and performed a 3-minute psychomotor vigilance test (PVT) before and after standing watch. Actigraphy results show that crewmembers were chronically sleep deprived, receiving on average 6.6 hours of daily sleep. Rest and sleep opportunities were varied significantly depending on the department to which the crewmember belongs. Specifically, the Operations department, followed by Engineering, had the worst sleep patterns as indicated by reduced and fragmented sleep. Using actigraphic recordings, approximately 22% of the participants occasionally napped during their night watch. Although not statistically significant due to its large variability, the pattern of PVT results agrees with the sleep analysis. In conclusion, this study provides evidence that the department to which a crewmember belongs is a factor to be taken into account when assessing performance at sea. In our sample, results demonstrate that the two departments most affected are the Operations and the Engineering. Both of these departments have critical duties while underway, yet they experience the most sleep deprivation. Future efforts should strive to further quantify this phenomenon and to address methods to ameliorate the problem.
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