Sex differences in U.S. Navy sailor well-being, sleep-related behaviors, and psychomotor vigilance performance.

Study objectives: To assess differences in sleep, well-being, sleep-related behaviors, and performance between sexes in active-duty Sailors in the U.S. Navy (USN).

Methods: Fit-for-duty Sailors (N = 1193, 21.6% females, median age 26 years) from 10 USN ships wore actigraphs for ~2 weeks, performed 3-minute Psychomotor Vigilance Tasks (PVTs), and logged daily habits while tending to their underway duties. At the end of the study, participants completed questionnaires to assess mood and well-being. Data were analyzed retrospectively.

Results: Compared to males, females slept 24 minutes/day more (p < .001, η² _p = 0.032), but their sleep was split into more episodes (p = .016, η² _p = 0.006). Females reported higher (worse) daytime sleepiness scores (p = .049, η² _p = 0.003) and more female sailors were identified with symptoms of excessive daytime sleepiness (p = .037, OR = 1.35). Females performed worse on the PVT (all p < .001, η² _p = 0.041 to 0.109) and reported worse vigor-activity scores (p = .005, η² _p = 0.009). The two sexes did not differ in the severity of insomnia symptoms (p = .323) and subjective sleep quality (p = .155). Even though the prevalence of drinking caffeinated beverages did not differ between sexes (p = .666), more females reported drinking tea (p < .001, OR = 2.12) and more males reported drinking energy drinks (p < .001, OR = 1.77). Fewer females reported having an exercise routine (p = .037, OR = 1.40).

Conclusions: We identified substantive sex differences in fit-for-duty sailors performing their underway duties. Taken together, our findings shed light on the expression of sex differences in the operational naval environment and emphasize the need to consider these differences to support Sailors as they meet the demands of military work.