The vital signs are, by definition, the measurements of the body's most basic functions. So far, the essential number of signs that must be measured is not clear as some references consider that the body temperature, blood pressure, pulse rate and breathing rate are sufficient but other sources consider that the measurement of other variables, such as the respiratory effort and oxygen saturation, are also crucial to determine the health of the person. This book is not intended to define the critical vital signs but presents the correlation of these measurements with other variables as well as the proposition of new methods to determine these variables. It also proposes some innovative applications that relay on these signs in a way to monitor and help the human being. Thus, this book presents six chapters that deal first with the correlation between the physical training and the blood pressure level among adults as well as the stress effects for nurses on their vital signs. Added to that, the influence of the vital signs to predict and detect epileptical seizure and the analysis of neural mechanisms of major depressive disorders will be also presented. As for the other chapters, they go into some engineering applications related to vital signs as the development of a smart syringe pump that monitors the patient's crucial parameters and the introduction of a novel system that monitors the driver's health and notifies health care providers in case the driver has any health failure in order to prevent cars accidents.