1. A mobile device of a vehicle operator, the mobile device comprising: a display; one or more sensors, including a first camera and a second camera; a processor; and a memory storing instructions that, when executed by the processor, cause the mobile device to present to the vehicle operator, on the display, a user interface with at least one sensitivity adjustment control, the at least one sensitivity adjustment control being adjustable by the vehicle operator to control sensitivity of impairment monitoring, detect a sensitivity setting of the at least one sensitivity adjustment control, the sensitivity setting resulting from an adjustment of the sensitivity adjustment control by the vehicle operator via the user interface, generate first impairment log entries by (i) monitoring the vehicle operator with the first camera while the vehicle operator operates a vehicle, (ii) determining whether each of one or more characteristics of the vehicle operator exceed a respective threshold, and (iii) generating an impairment log entry for each instance in which one of the one or more characteristics exceeds its respective threshold, generate second impairment log entries by monitoring an environment ahead of the vehicle with the second camera, determine a total impairment score for the vehicle operator, at least by (i) assigning a plurality of scores based on the first impairment log entries and the second impairment log entries, and (ii) performing a mathematical operation on the plurality of scores, determine whether the total impairment score exceeds a score threshold, wherein one or both of (i) determining the total impairment score, and (ii) determining whether the total impairment score exceeds the score threshold, is based on the sensitivity setting, in response to determining that the total impairment score exceeds the score threshold, present an alert to the vehicle operator.