In Human-Computer Interaction (HCI) and Ubiquitous Computing, the objective of optimizing device interactions and personalizing user experiences has placed a new emphasis on accurately evaluating cognitive readiness using wearable devices. Interpreting cognitive readiness in real-world scenarios is complex due to the plethora of potential physiological measures, individual variability, and the limitations of wearable devices. In this review, we present a systematic overview of key physiological measures that can be used for an in-depth assessment of cognitive readiness. These measures can serve as proxies for detailed assessments of cognitive readiness. This review serves as a tool for assessing cognitive readiness for diverse applications, with special focus on in-the-wild research settings. In addition, due to the complexity of measurements and devices, we propose the development of robust catalog for cognitive readiness measurements.