Centre for Military Medicine, The Finnish Defence Forces, Turku, Finland.
Doctoral Programme in Clinical Research, University of Turku, Turku, Finland.
Chronobiol Int. 2022 Sep;39(9):1233-1241. doi: 10.1080/07420528.2022.2090374. Epub 2022 Jun 28.
The operation of naval vessels involves watchkeeping 24 h per day, which is globally carried out by a variety of different watch systems. In this study, the rotating 4:4 and fixed 4:4/6:6 two-section watch systems were compared in terms of sleepiness, fatigue, and stress responses. The data collection took place on a Finnish Defence Forces' (FDF) Navy missile patrol boat with 15 crew members serving as study participants. The data collection periods lasted two separate weeks (7 days, 6 nights) with the different watch systems. The subjective sleepiness of the participants was assessed before and after every watch using the Karolinska Sleepiness Scale (KSS). Stress responses were assessed daily by the recorded levels of salivary alpha-amylase (sAA), cortisol (sCor), immunoglobulin A (sIgA), and dehydroepiandrosterone (sDHEA). The participants' sustained attention, inhibitory control, and working memory were assessed daily by cognitive tests (SART, N-Back). The heart rate variability (HRV) during an orthostatic test was used as an additional daily marker to assess the amount of psychological stress of the participants. In this study, the difference regarding sleepiness and fatigue between the study weeks was most visible in the subjective KSS, which clearly favored the 4:4/6:6 system. The results of sAA and sIgA also suggested that the subjects were psychologically less stressed during the study week with the 4:4/6:6 watch system. Cognitive test results (SART, N-Back) indicated that there were overall no significant differences in the subjects' sustained attention, inhibitory control, or working memory during the study weeks or between the study weeks. The results of the HRV data during the daily orthostatic tests were inconclusive but there was some indication that the subjects were less stressed during the study week with the 4:4/6:6 watch system. In conclusion, the present study indicates that in navy surface operations: working with the fixed 4:4/6:6 watch system causes less sleepiness, fatigue, and psychological stress than working with the rotating 4:4 watch system. The study result is well in line with previous research regarding watch systems.
军舰的操作涉及每天 24 小时值班，这在全球范围内由各种不同的值班系统来完成。在这项研究中，比较了旋转的 4:4 和固定的 4:4/6:6 两段式值班系统在困倦、疲劳和应激反应方面的差异。数据采集在一艘芬兰国防军（FDF）海军导弹巡逻艇上进行，有 15 名船员作为研究参与者。数据采集期持续了两周（7 天，6 个晚上），使用了不同的值班系统。参与者的主观困倦程度在每次值班前后使用 Karolinska 困倦量表（KSS）进行评估。应激反应每天通过唾液α-淀粉酶（sAA）、皮质醇（sCor）、免疫球蛋白 A（sIgA）和脱氢表雄酮（sDHEA）的记录水平进行评估。参与者的持续注意力、抑制控制和工作记忆每天通过认知测试（SART、N-Back）进行评估。直立测试期间的心率变异性（HRV）作为评估参与者心理压力程度的附加每日标志物。在这项研究中，研究周之间的困倦和疲劳差异在主观 KSS 中最为明显，4:4/6:6 系统明显更受青睐。sAA 和 sIgA 的结果也表明，在研究周期间，4:4/6:6 值班系统使受试者的心理压力更小。认知测试结果（SART、N-Back）表明，在研究周期间，受试者的持续注意力、抑制控制或工作记忆没有总体显著差异，也没有在研究周之间存在显著差异。每日直立测试 HRV 数据的结果不确定，但有一些迹象表明，在研究周期间，4:4/6:6 值班系统使受试者的压力更小。总之，本研究表明，在海军水面作战中：与旋转的 4:4 值班系统相比，使用固定的 4:4/6:6 值班系统会导致更少的困倦、疲劳和心理压力。研究结果与之前关于值班系统的研究结果一致。
