Unobtrusive vital signs monitoring is of major importance for various medical areas such as detection and treatment of sleep disorders, monitoring neonates and burned victims, home health care and smart home applications and wearables among others. Such applications call for monitoring methods in which the patient's natural state is less interfered with. An ideal device would be non-invasive, minimally restrictive, robust enough to compensate movements of the patients, and would operate without relying on the patient's full cooperation.