Estimation of the workload with visual display terminal by salivary immune substance

Psychophysiological studies have revealed the close relationship between subjects´ mental states and his/her secretion of hormones and immune substances. In this study, one of the major secretory immune substance, secretory Immunoglobulin A, was assessed as a biomarker of the workload with visual display terminal (VDT). In the experiment, subjects were required to conduct a VDT work including break. As a result, IgA changed closely to the work/break schedule. Besides, the integration of IgA through out the experiment was also observed. Additionally, a simple mathematical model was proposed to explain such an integrative IgA change. Finally, the result of the experiment and simulation is discussed in relation to the possibility of estimation and anticipation of subjective stress cause by VDT workload.