Evaluation of Mental Stress and Heart Rate Variability Derived from Wrist-Based Photoplethysmography

Heart Rate Variability (HRV) is a significant indicator of physical fitness and mental stresses. Electrocardiography (ECG) is the most common means to detect HRV. However, the nature of the ECG detection limits its convenience and usage time. While wrist-based Photoplethysmography (PPG) provides the possibility of convenient 24/7 HRV monitoring, its accuracy has not been systematically analyzed. We experimented with six healthy subjects and measured PPG from their wrist and ECG from their chest. The result shows that ten HRV parameters have significant differences between stress and non-stress states. Furthermore, the 10-fold accuracy of stress state detection within subjects is 98% and the Leave-One-Participant-Out F1score reaches 80%. The results demonstrate that wrist-based PPG can provide HRV measurements that enable the recognition of mental stress as accurately as ECG, even for a short three-minute temporal window.