A SIMULATION STUDY OF THE EFFECTS OF SLEEP DEPRIVATION, TIME OF WATCH AND LENGTH OF TIME ON WATCH ON WATCHSTANDING EFFECTIVENESS (VIGILANCE, MARITIME, FATIGUE)

The primary purpose of this research was to measure the effects of sleep deprivation, time of watch, and length of time on watch on a watchstander's work performance and on psychological and physiological measures in a simulated open-sea watch. A second purpose was to evaluate marine simulation as a method for studying the effects of such variables on mariner performance.; Sleep deprivation is a common problem among mariners and was the primary variable of interest. Time of watch and length of time on watch were examined because of their interrelationship with the fatiguing effects of sleep deprivation. The standard work schedule of watch officers--four hours on and eight hours off work--is discordant with the typical work/rest schedules and accompanying circadian rhythm of most people. Thus, this watch schedule was expected to mediate the effects of sleep deprivation on watchstanding. The length of time which a watch officer has stood a relatively uneventful watch was also expected to interact with the effects of sleep deprivation, such that the deleterious effects of sleep deprivation would be exacerbated as time on watch increased.; Twenty-five watchstanding mates were assigned to one of four experimental groups: Group 1 slept for 7.5 hours, then stood a morning watch; Group 2 slept for 7.5 hours, then stood an afternoon watch; Group 3 received no sleep before standing a morning watch; Group 4 received no sleep before standing an afternoon watch. All watches were stood on the bridge of a full-scale full-mission shiphandling simulator. Dependent measures were collected before, during, and after a four-hour watch. Dependent measures included speed of traffic ship detection, radar observation, and measures of affect, cognition, and physiological state.; Sleep deprivation appeared to have a deleterious effect on watchstanding vigilance, especially for those mates standing the afternoon watch. Conclusions were based on many weak indicators, however, rather than a few strong effects.