Critically ill patients commonly experience poor sleep quality and sleep deprivation. Aim: assess nurses' performance regarding acquired sleep deprivation among critically ill patients. Design: Descriptive exploratory research design. Setting: General Intensive Care Unit of Beni-Suef University Hospital. Methods: A convenient sample of all available nurses (40 nurses) who worked at General Intensive Care Unit at Beni-Suef University Hospital. Tools: Tool (I) Interview Self- administered Nurse's Questionnaire consisted of 2 parts; Part (I): Questionnaire to assess demographic characteristics of studied nurses. Part (II): Nurses' level of knowledge tool. Tool (II): observational checklist to assess nurses' level of practice Results: The study results revealed that 57.5% of the studied nurses had unsatisfactory total level of knowledge and 85% of the studied nurses had incompetent total level of practice regarding acquired sleep deprivation among critically ill patients. Conclusion: It can be concluded that there was a statistically significant positive correlation between total level of knowledge score and total level of practice score Recommendation: Developing follow up courses and training programs to improve nurses' performance regarding acquired sleep deprivation among critically ill patients.