Delirium is a common complication among survivors of traumatic brain injury (TBI). Although prior studies have predominantly focused on delirium onset following moderate to severe TBI, mild TBI accounts for the majority of TBI cases in hospital settings. However, key risk factors for delirium in this population remain unclear. In this prospective observational study, we analyzed changes in sleep parameters and circadian rhythm during the first 7 days following mild TBI among patients in a neurosurgical ward. We further identified the key factors associated with post-TBI delirium. This study included 100 patients with mild TBI. Delirium was evaluated using the traditional Chinese version of the 4 A's Test (4AT). Sleep parameters and circadian rhythms were monitored through actigraphy for up to 7 consecutive days following admission. Risk factors for post-TBI delirium were identified through univariate and multivariate regression analyses. A total of 12 patients developed delirium, three of whom exhibited delirium onset immediately before their first nighttime sleep. Therefore, the actigraphic data of these individuals were exclusively classified as post-delirium. The remaining 97 patients were categorized into delirium and nondelirium groups. Interdaily stability was significantly lower in the delirium group than in the nondelirium group (0.27 vs. 0.48, p = 0.007). Risk factor analysis revealed that each one-unit increase in interdaily stability was associated with an 84% reduction in delirium risk (adjusted hazard ratio: 0.16, 95% confidence interval [CI]: 0.03-0.78). In summary, circadian rhythm disruptions are associated with an increased risk of delirium following mild TBI. This study underscores the importance of circadian rhythm stability and may inform targeted interventions aimed at preventing delirium in this patient population.
