Comparison of the 3/9 and 6/6 Watchstanding Schedules for Crewmembers of a U.S. Navy destroyer

This naturalistic study of 52 sailors on the USS Jason Dunham (DDG-109) compared actigraphic sleep and psychomotor vigilance performance of crewmembers working a 3hours-on/9hours-off (“3/9”) with the performance of their counterparts who worked a 6hours-on/6hours-off (“6/6”) watchstanding schedule. Crewmembers on the 3/9 slept more (6.46±0.77 hours) and reported less daytime sleepiness (Epworth Sleepiness Scale (ESS) score = 10.7±3.70) than their peers on the 6/6 schedule (sleep 5.89±0.87 hours; ESS = 13.1±3.45). The length of the workday for participants on the 6/6 schedule was 15 hours compared to 12.2 hours for crewmembers on the 3/9. Based on 11 of 13 Psychomotor Vigilance Task metrics, performance of crewmembers on the 6/6 schedule had significantly greater variability than the 3/9 sailors (p<0.05). Overall, participants evaluated the 6/6 as being worse and the 3/9 as the better schedule. Results showed that the 3/9 outperformed the 6/6 in terms of daily sleep duration, fatigue levels, psychomotor vigilance performance, and acceptance from the participants.