## 1 Introduction
### Wearable Sensors  
The prevalence and availability of wearable smart sensors has taken the concept of stress detection and monitoring to a new level [14]. Wearable sensors have become an integral part of our daily lives. They provide easy access to information about our health status from anywhere in the world. Visits to the hospital are no longer necessary for measuring one's pulse and blood pressure [15]. Evaluating one's health status is crucial for assessing the body's condition, both at resting and under various external stimuli, as well as during the progression of many diseases. One of the significant risk factors that can lead to the development of various diseases and pathological conditions is stress. Whether acute or chronic, stress has become a common part of life for many individuals, acting as a daily trigger that can significantly diminish quality of life. The current generation has not been immune to global stressors, such as pandemics and wars, which inevitably lead to economic crises [16]. These challenges affect everyone, either directly or indirectly. Thus, it is essential to seek early methods for detecting stress to prevent the onset of diseases without disrupting the daily routine by integrating stress detection technology into wearable devices. Stress presents serious health risks, particularly concerning cardiovascular disease, strokes, mental disorders, cancers, and a weakened immune system. It induces psychophysiological changes and exacerbates psychological issues [17]. Therefore, the number of people who prefer wearable sensors as monitoring tools is growing every year [14; 15; 18]. Various methods exist for detecting and monitoring stress, which can be categorized into three main groups: psychological, physiological, and detection of stress using technological devices [18; 19; 20]. Physiological methods focus on identifying changes in bodily parameters that occur in response to stress, such as skin conductance, heart rate variability, heart rate, and ECG readings. While these methods are informative, as demonstrated by numerous studies, they have certain limitations, particularly the requirement for specialized medical equipment and trained healthcare professionals. Psychological approaches to stress assessment typically involve questionnaires, surveys, and cognitive tests. However, a notable limitation of these methods is their inherent subjectivity. In contrast, the use of technological devices, such as wearable technology and artificial intelligence, offers a promising and objective alternative for stress evaluation [21]. These devices are user-friendly and enable rapid, accurate, and reliable monitoring of relevant physiological indicators, thus facilitating timely detection of stress. Furthermore, these methods are largely free of significant drawbacks, and the data collected can be transmitted to medical professionals for further analysis when necessary. Modern versions of these devices primarily rely on analyzing cardiovascular indicators [22], such as heart rate variability and heart rate, which are regulated by both the autonomic nervous system (including sympathetic and parasympathetic branches) and the endocrine system. However, it is crucial to recognize that certain cardiovascular parameters can be consciously controlled. For example, heart rate can be reduced through deep breathing or by applying pressure to the eyes (a phenomenon known as the Aschner reflex) [23]. On the other hand, indicators such as skin conductance or skin resistance cannot be consciously controlled. These indicators are therefore crucial for determining stress, and it is also important that they can be easily recorded by wearable sensors [24]. Changes in skin conductance are associated with sweating, which is influenced by stress [25]. Under stressful conditions, most individuals experience activation of the sympathetic nervous system, leading to the release of catecholamines, while activation of the hypothalamus triggers cortisol release.