Topological Model of Human Fatigue and Drowsiness

Objectives.
Severe fatigue or drowsiness leads to poor work quality and, in many professions, can result in fatal outcomes. Therefore, it is crucial to develop monitoring systems for these states. The aim of this study is to create an informative and easily measurable set of parameters for monitoring these conditions.
Materials and Methods.
The study employs topological modeling (TM) of complex functioning heterogeneous systems, developed at Riga Technical University, for the diagnosis and recovery of technical and biological systems. In biology and medicine, TM began with the modeling of disease pathogenesis. The model is constructed as a directed graph consisting of cause-effect chains that represent processes occurring in the organism. The vertices of the model are the parameters of the process under study, and the directed edges reflect the impact of one parameter on another. The cause-effect chains start with the triggering factor and end with the output parameter. Knowledge about the process under study is organized into three levels: causes or triggering factors, the resulting changes in organism functions, and the manifestations of these changes—symptoms. The model is created by a group of experts.
Results.
A topological model of the mental component of human fatigue and the development of drowsiness has been created. The model consists of 69 vertices and 74 edges, which are assigned numerical values by a group of experts with an appropriate concordance or consensus coefficient. The formalized TM processing was performed using graph theory. As a result, a set of parameters for determining fatigue and drowsiness was selected.
Conclusions.
The analysis of TM cause-effect chains allows us to conclude that mental fatigue and drowsiness are distinct concepts. The formalized methodology for selecting measurable parameters ensures that only informative and easily obtainable parameters are included in the set.