Significant resources have been invested toward the development of systems that adapt to user functional state in real-time and based on users' physiological responses, where the user may be in a wide array of stressful situations. These adaptive systems are promising as platforms to enhance training effectiveness, yet progress to date has been somewhat limited. The physiological responses to a stressful situation have been characterized as “fight-or-flightâ€� or “challenge vs. threatâ€� responses. The cardiovascular changes associated with these responses are mediated by the autonomic nervous system and include both central (e.g., heart rate, stroke volume) and peripheral (e.g., blood pressure, total peripheral resistance) changes. Blood pressure (BP) is modulated acutely by the baroreflexes. Baroreceptors are stretch-sensitive mechanoreceptors located in the vasculature which provide negative feedback to the brain; changes in BP change this stretch and ultimately lead to changes in BP and heart rate (HR). Both physical exercise and mental stress can increase HR and BP. However, baroreflex sensitivity is unchanged with physical exercise and limited evidence suggests it is altered with mental stress. Changes in baroreflex sensitivity may therefore provide an objective marker for mental stress that HR- and BP-based markers cannot. Thus, real-time monitoring of baroreflex sensitivity may be the missing component for bridging the gap in developing an effective adaptive system. Consequently, the purpose of this study was to assess the extent to which baroreceptor sensitivity changes during acute physical stress (cold pressor test), laboratory-based mental stress (Stroop test, mental arithmetic, anagrams) and using a virtual reality environment, stressful occupationally-relevant “real-lifeâ€� simulations. We will then propose a framework for the utilization of baroreflex sensitivity measures as a tool for assessing laboratory and occupational stressors in real-time.