A head-worn system has one or more illumination, imaging, communication, and/or other controlled elements electrically connected to a switch element (e.g., a piezo switch) positioned on the head-worn system so as to be overlying an area of a wearer's masseter muscle when worn on the wearer's person. The switch element is configured to be activated responsive to clenching of the wearer's jaw. The one or more controlled elements may be arranged to provide directional lighting/imaging from the point of view of the wearer, for example from the area of the wearer's zygomatic bones, when the head-worn system is worn on the wearer's person.