1. A method for detecting a stress disorder: exposing a subject to a stimulus; collecting, with a plurality of sensors, a plurality of physiological signals during the subject's exposure to the stimuli, the plurality of physiological signals comprising at least an interbeat interval signal and a skin conductance signal; extracting a feature from each of the plurality of physiological signals; and classifying the subject into one of a first category indicating the subject is suffering from post-traumatic stress disorder, a second category indicating the subject is not suffering from post-traumatic stress disorder, or a third category indicating the subject was exposed to a traumatic event but does not suffer from post-traumatic stress disorder based on a function of the extracted features.