Embodiments of the present disclosure disclose a method and system for determining health condition of a subject. First step of the method comprises receiving, by a computing unit, a first oxygen saturation level and a second oxygen saturation level from at least two sensors placed on the subject. Second step of the method comprises determining cerebral extraction of oxygen using the first and second oxygen saturation levels. Third step of the method comprises comparing the cerebral extraction of oxygen with a threshold level. Fourth step of the method comprises identifying a mental fatigue level of the subject based on outcome of the comparison, wherein the mental fatigue level indicates the health condition of the subject.
