Assessment of the fixed 3-section 4hrs-on/8hrs-off watchstanding schedule in sailors of the Swedish Royal Navy compared to sailors of the United States Navy

Abstract

This prospective longitudinal quasi-experimental study assessed the utility of the 3-section, fixed, 4hrs-on/8hrs-off watchstanding schedule on a ship of the Swedish Royal Navy (HSwMS ORIOΝ). Sailor (n = 19) state was assessed in terms of sleep attributes, fatigue, insomnia symptoms, mood, psychomotor vigilance performance, and workload. Data from the HSwMS ORIOΝ were compared with data from sailors from three surface vessels of the USN (n = 22). Compared to their USN peers, sailors on the HSwMS ORION were more alert, reported better sleep quality, less severe insomnia symptoms, and better mood in terms of total mood disturbance, depression, fatigue, and vigor. The same pattern was evident in psychomotor vigilance performance, i.e., sailors on the HSwMS ORION were faster and made fewer errors as assessed by lapses or lapses combined with false starts. Sailors in the two samples did not differ in terms of daily sleep duration and the number of sleep episodes per day. Also, daily work duration did not differ substantively between the two groups. We postulate that one factor that explains why Swedish sailors felt and performed better is the fact that sailors in night shifts were allowed to wake up later in the day, and, consequently some work duties occurred later in the day. In conclusion, our findings suggest the sailor well-being when standing watch on the fixed 4/8 can be improved when sailors are allowed flexible wake-up times in the morning after a night shift. Given the small number of participants, however, further research is needed to understand better the advantages and disadvantages of the 4/8 in the naval operational environment, and how to improve the utility of the watchbill.