Although observation largely takes into account the needs and abilities of individuals with profound intellectual and multiple disabilities, several difficulties are related to this assessment method as well. Our aim in this study was to investigate what possibilities the use of physiological measurements make available to validate alertness observations. Measurements of five physiological parameters were compared with video observations of three individuals with profound intellectual and multiple disabilities. Because our first findings are broadly in line with those of studies involving individuals in the general population, we hypothesize that physiological measurements can be used to validate alertness observations in individuals with profound intellectual and multiple disabilities. Future studies are needed to compensate for the limitations of this study and to answer ensuing questions.