Sleep monitoring in the intensive care unit: comparison of nurse assessment, actigraphy and polysomnography

Objective: Sleep loss and sleep disruption are common in critically ill patients and may adversely affect clinical outcomes. Although polysomnography remains the most accurate and reliable way to measure sleep, it is costly and impractical for regular use in the intensive care unit. This study evaluates the accuracy of two other methods currently used for measuring sleep, actigraphy (monitoring of gross motor activity) and behavioural assessment by the bedside nurse, by comparing them to overnight polysomnography in critically ill patients. Design: Observational study with simultaneous polysomnography, actigraphy and behavioural assessment of sleep. Setting: Medical-surgical intensive care unit. Patients and participants: Twelve stable, critically ill, mechanically ventilated patients [68 (13) years, Glasgow coma scale 11 (0)]. Interventions: None. Measurements and results: Sleep was severely disrupted, reflected by decreased total sleep time and sleep efficiency, high frequency of arousals and awakenings and abnormal sleep architecture. Actigraphy overestimated total sleep time and sleep efficiency. The overall agreement between actigraphy and polysomnography was < 65%. Nurse assessment underestimated the number of awakenings from sleep. Estimated total sleep time, sleep efficiency and number of awakenings by nurse assessment did not correlate with polysomnographic findings. Conclusions: Actigraphy and behavioural assessment by the bedside nurse are inaccurate and unreliable methods to monitor sleep in critically ill patients.