Coherence Between Sleep Detection by Actigraphy and Polysomnography in a Multi-Center, Inpatient Cohort of Individuals with Traumatic Brain Injury

Background: Sleep is increasingly recognized as a crucial component to rapid and successful rehabilitation, especially from traumatic brain injuries (TBIs). Assessment of longitudinal patterns of sleep in a hospital setting, however, are difficult and often the expertise or equipment to conduct such studies is not available. Actigraphy (wrist-worn accelerometry) has been used for many years as a simple proxy measurement of sleep patterns, but its use has not been thoroughly validated in individuals with TBI. Objective: To determine the validity of different sensitivity settings of actigraphy analysis to optimize its use as a proxy for recording sleep patterns in individuals with a TBI. Design: Comparison of actigraphy to criterion standard polysomnographic (PSG)-determination of sleep on a single overnight study. Setting: Six rehabilitation hospitals in the TBI Model System. Participants: Two hundred twenty-seven consecutive, medically stable individuals with a TBI. Interventions: Not applicable. Main Outcome Measure: Concordance between PSG- and actigraphy-determined sleep using different sensitivity threshold settings (low, medium, high, automated). Results: Bland-Altman plots revealed increasing error with increasing amounts of wake during the sleep episode. Precision-recall statistics indicate that with less sensitive actigraphy thresholds, episodes identified as “wake” are usually “wake,” but many true episodes of “wake” are missed. With more sensitive actigraphy thresholds, more episodes of “wake” are identified, but only some of these are true episodes of “wake.”. Conclusions: In hospitalized patients with TBI and poor sleep, actigraphy underestimates the level of sleep disruption and has poor concordance with PSG-determined sleep. Alternate methods of scoring sleep from actigraphy data are necessary in this population.