Using Non-Contact Imaging Photoplethysmography to Recover Diurnal Patterns in Heart Rate.

Daily patterns in cardiovascular signals can reveal important information about physiological processes, health and well-being. Traditionally, contact sensors have been used to collect longitudinal data of this kind. However, recent advances in non-contact imaging techniques have led to algorithms that can be used to measure vital signs unobtrusively. Imaging methods are highly scalable due to the availability of webcams and computing devices making them attractive for longitudinal, in-situ measurement. Using a software tool we captured over 1,000 hours of non-contact heart rate measurements, via imaging photoplethysmography. Using these data we were able to recover diurnal patterns in heart rate during the working day. Non-contact sensing techniques hold much promise but also raise ethical issues that need to be addressed seriously within the biomedical engineering community.