0180 Crew Sleep During a 36-day Arctic Transit: Preliminary Results

Abstract Introduction Extreme environmental conditions (e.g., natural light conditions, time zone transitions), and specific operational conditions (e.g., ship motion due to ice breaking) combined with a variety of other occupational stressors (including shift work, psychological stress, and performing physically strenuous activities), poses unique challenges when conducting polar operations. The overarching aim of this project is to assess the unique challenges sailors experience when operating in polar regions in order to identify performance-limiting factors derived from operating an icebreaker in extreme latitudes. This abstract shows preliminary results of crewmember sleep. Methods A naturalistic longitudinal approach assessed 53 of the ship’s crewmembers (median age of 29yrs; 71.7% males; 66.0% enlisted) while performing their normal duties during a 36-day transit from Kodiak, AK (8/26/23) to Tromsø, Norway (1/10/23). Participants wore ŌURA rings and completed weekly questionnaires throughout the study. Mixed effects analysis was used to assess the effect of age, occupational group, time underway, and watchstanding status on variables of interest. Results are presented as mean◻standard deviation. Results Over the entire data collection period, participants’ sleep duration was 6.81◻0.57 hrs/day with 68.9% sleeping 7 hrs/day and 8.89% sleeping 6 hrs/day. All participants napped at least once; 68.1% napped at least once every 4 days. Self-report sleep regularity index (SRI; lower numbers translate to poorer sleep) was 73.1◻5.80 for watchstanders, 83.8◻6.19 for non-watchstanders, and 78.3◻5.16 for crewmembers with a hybrid work schedule. Age was associated with decreased heart rate variability (p=0.006), increased percentage of light sleep (p 0.001), decreased percentage of deep sleep (p 0.001), and increased percentage of REM sleep (p=0.021). Officers and watchstanders had a lower percentage of REM sleep compared to enlisted (p=0.030) and non-watchstanders (p=0.025) respectively. Also, over the course of the underway the percentage of light sleep increased and the percentage of deep sleep decreased. Specifically, compared to Week 1, Week 3 had a higher percentage of light sleep (p=0.027), and a lower percentage of deep sleep (p=0.019). Conclusion Results showed that Arctic operations can affect crew sleep. Crew members slept less than the daily recommended 7+ hr/day sleep duration. Their sleep was also related to age, watchstanding status, and time underway. Support (if any)