Measurement of sleep in critically ill patients.

Research to evaluate interventions to promote sleep in critically ill patients has been restricted by the lack of brief, inexpensive outcome measures. This article describes the development and testing of an instrument to measure sleep in critically ill patients. A convenience sample of 70 alert, oriented, critically ill males was studied using polysomnography (PSG), the gold standard for sleep measurement, for one night. In the morning the patients completed the Richards-Campbell Sleep Questionnaire (RCSQ), a five-item visual analog scale. Internal consistency reliability of the RCSQ was .90 and principal components factor analysis revealed a single factor (Eigenvalue = 3.61, percent variance = 72.2). The RCSQ total score accounted for approximately 33% of the variance in the PSG indicator sleep efficiency index (p < .001). The data provide support for the reliability and validity of the RCSQ.