## 2 Literature Review
Seafarer performance directly affected shipping safety, while job satisfaction and work stress indirectly affected shipping safety through seafarer performance. This indicated that seafarer performance was most directly impacted by work stress rather than job satisfaction and that seafarer performance was most directly correlated with shipping safety [19]. Maritime navigators, despite reporting generally low levels of perceived stress, experience stress primarily shaped by self-doubt in their coping abilities, which highlights the importance of self-efficacy in safeguarding against burnout and maintaining occupational resilience [20]. Additionally, perceived stress is significantly moderated by individual resilience and prior seafaring experience, although the time spent at sea does not appear to be a determining factor [21]. Dispositional resilience has been found to be the strongest predictor of perceived stress, although a just and supportive work environment remains essential for mitigating its impact [22]. Positive spillovers from personal life, particularly marital satisfaction, also play a key role in buffering the effects of stress and reducing anxiety [23]. While these personal and occupational factors contribute to baseline stress, navigational situations, particularly ship encounters, introduce acute stressors that cause an elevated mental workload (MW) and complicate decision-making processes. According to several studies, these factors are key contributors to human errors, often leading to accidents. When the MW exceeds manageable thresholds, performance declines [24], impairing decision-making and increasing the likelihood of errors [25], thereby compromising safety [26]. An excessive workload, often associated with high levels of stress [27], also contributes to fatigue, which severely affects ship safety. Fatigue results from various factors, including inadequate and poor-quality sleep and rest [28]. This effect is particularly significant for officers responsible for the vessel's safety and security. In the era of automation, operators' MWs are similarly impacted [29]. Therefore, managing the MW is critical for ensuring safety, especially during ship encounters in port approaches or confined waters. In this study, we assessed these stress and workload dynamics using two complementary approaches. First, the PSS [30], a widely used self-report scale for measuring perceived stress [31], captured the subjective stress experiences of ship navigators. Second, the physiological responses were evaluated through HRV, which measures the variation in time intervals between heartbeats and reflects autonomic nervous system (ANS) activity. HRV was selected as a physiological indicator due to its established role in reflecting stress-related autonomic regulation [32]. Typically, an individual's HRV is higher during restful states, indicating parasympathetic (vagal) dominance, and it decreases during periods of physical or psychological stress, reflecting heightened sympathetic tone. The HRV levels also vary with individual factors, generally being higher in younger, physically fit, and healthy populations [33; 34]. The ANS regulates an individual's heart rate (HR) through a balance of sympathetic and parasympathetic inputs. Sympathetic activation increases an individual's HR and reduces their HRV, while parasympathetic activity lowers an individual's HR and increases their HRV [35]. This balance is modulated by the central autonomic network, with rapid HR fluctuations mediated by mechanisms such as the baroreceptor reflex and respiratory sinus arrhythmia. HRV is most accurately captured through electrocardiography (ECG), although calibrated non-ECG methods such as photoplethysmography can also be used. Previous research has consistently demonstrated an inverse relationship between perceived stress (as measured by the PSS) and HRV, reflecting a physiological link between psychological stress and autonomic dysregulation [36].