Influence of mental stress on the pulse wave features of photoplethysmograms

Abstract

Mental stress is a major burden for our society. Invasive and non-invasive methods have been proposed to monitor and quantify it using various sensors on and off body. In this study we investigated the use of the arm photoplethysmogram (PPG) to assess mental stress in laboratory conditions. Results were in correspondence with our previous in silico study which guided the present study. Three wave shape parameters were identified for stress assessment from the PPG signal: 1) the time from dicrotic notch to end diastole; 2) the time from pulse onset to systolic peak; and 3) the ratio of diastolic to systolic area. Our in vivo results showed that the two first parameters responded significantly to increased mental stress and to a breathing relaxation procedure, indices of stress.