Sleep in military submariners: exploring its dynamics in relation to a submarine mission and interaction with psychological factors

Introduction: Operational work contexts promote sleep and circadian disturbances, especially in extreme environments. To identify mitigation factors, this study aimed to explore submariners’ sleep changes in relation to a mission and association with different psychological factors. Methods: Thirty military submariners were evaluated in real-life conditions on three consecutive periods: pre-mission/baseline, submarine mission, post-mission/recovery. Sleep duration, quality, and sleepiness were collected continuously via diary and actigraphy. Personality traits, coping strategies, locus of control, fatigue, anxiety, and depressive symptoms were assessed through questionnaires. Results: During the mission, there was a significant decrease in sleep duration and quality and increase in sleepiness compared with baseline, recovering post-mission. Submariners slept a median of 55 minutes less than before the mission and 91 minutes less than after the mission. They also rated their sleep quality 0.45 points lower, while reporting 1.85 points higher sleepiness at the beginning of work shifts. Higher work satisfaction and extraversion trait score correlated with better scores on subjective sleep variables during the mission. Higher neuroticism trait and avoidant coping style had a negative impact on sleep-related parameters in all periods, mediated by anxiety symptoms. Conclusion: Psychological factors are relevant for sleep in extreme occupational settings, especially regarding subjective parameters, and even in highly selected and trained populations, potentially informing intervention opportunities.