The aim of maintaining optimal levels of sedation in critically ill patients is an important concern of intensive care nurses. In addition, the specific requirements of patients are individual and will vary according to the severity of their illness and/or supportive treatment that they may be undergoing (Hopkinson & Freeman 1988). The use of sedation in an intensive care unit (ICU) is therefore a complex nursing issue.The purpose of this literature review is to evaluate the need for ensuring that patients are receiving appropriate sedation whilst in an ICU. This is followed by consideration of what is meant by optimal levels of sedation, a review of past and current sedation practice and the importance of nurses assessing the depth of sedation of the critically ill patients within their care. Key points are raised, with recommendations for future nursing practice.