Sleep pattern disturbance is a common occurrence in critical care units. Nurses are often unaware of the magnitude of the sleep disturbance because of a lack of reliable, valid and feasible measures to assess sleep patterns. The purpose of this study was to determine the reliability and validity of a sleep perception tool and a sleep observation instrument for the trauma patient in a critical care setting. The research investigated the relationships among the measures of observed sleep, patient perception of sleep, and polysomnograph sleep data on the sleep traits: sleep latency, midsleep awakening, and wake after sleep onset. A purposive sample of 20 patients with multisystem trauma participated in this descriptive correlational study. Instruments used to measure sleep for one night were the Dynograph R-511A, the Patient's Sleep Behavior Observational Tool, and the Verran/Snyder Halpern Sleep Scale. Results of the multitrait-multimethod analysis revealed that observed wake after sleep onset met all the criteria for convergent and discriminant validity, with perceived awakenings demonstrating convergent validity alone with polysomnographic awakenings lasting longer than 4 minutes. All sleep variables were reliable. It is concluded that nursing observation of trauma patients' wakefulness can be used to test sleep-promoting interventions.