P073 The sleep, performance, and physiological health consequences of watchkeeping schedules: A scoping review

Watchkeeping schedules are commonly used on submarines and expose personnel to circadian misalignment and sleep loss. This scoping review aimed to identify the most frequently investigated schedules and examine the effect they have on sleep, cognitive performance, and physiological health outcomes. Systematic searches took place on five online databases (MEDLINE, PsychINFO, PubMed, Scopus, Embase) and Google Scholar in May 2022. The inclusion criteria consisted of peer-reviewed journal articles, industry reports and both laboratory and field studies which directly measured or compared a watchkeeping schedule used on submarines. The initial search produced 4375 results and through screening, resulted in 20 mostly field-based studies for data extraction. Sleep was the most often outcome investigated with only a few studies looking at cognitive performance and/or physiological health. The 6h on/6h off was the most studied schedule which generally demonstrated poorer sleep, cognitive performance, and physiological health than other schedules (e.g., 4h on/8h off, 6h on/12h off). This is important as this schedule is the most frequently used by navies around the world. In other schedules, sleep and cognitive performance were poorest during the biological night, whilst physiological measures were indicative of circadian misalignment. The synthesis of studies in this review provides an understanding how the currently used watchkeeping schedules around the world negatively affect submariners and increase their risk for deleterious health outcomes. The review also highlights the need for future controlled research to understand how schedules might be improved.