The monitoring and assessment of the degree of conscious sedation experienced by patients is important for both clinical practice and in research. Whereas clinical monitoring remains the gold standard for safety in patient care, numerous measures are available to supplement this and to provide quantitative data on level of sedation. This manuscript provides an overview of existing measures of the degree of sedation. Scales that have been used in published research were identified from a search of Medline and Google Scholar, and for each scale we identified the characteristics of the scale and degree to which the reliability and validity of the scale had been measured.