Sleep assessment in critically ill patients with delirium

Background: Delirium is a frequent and severe pathological status in critically ill patients, associated with increased ICU stay, morbidity, and long-term cognitive impairment. Sleep disturbances are common in the ICU, but their relationship with delirium remains unclear. This study aimed to compare sleep quantity and quality between critically ill patients with and without delirium. Methods: In this post-hoc analysis of two prospective cohorts conducted at the University Hospital of Poitiers, 97 patients were included during the weaning period (45 under mechanical ventilation with difficult weaning and 52 patients breathing spontaneously immediately after extubation). Sleep was assessed using full polysomnography (PSG) as soon as possible after the first SBT failure or after extubation. Delirium was evaluated at the time of PSG using the Intensive Care Delirium Screening Checklist (ICDSC ≥ 4). Sleep quantity (total sleep time, light, deep, and REM sleep) and sleep quality (atypical sleep, EEG reactivity) were analyzed. Results: Delirium was present in 24 patients (25%). Median total sleep time was low in both groups and did not significantly differ between patients with delirium and the others (243 vs. 186 min, respectively, p=0.117). Atypical sleep was more frequent in patients with delirium (46% vs. 26%, p=0.075). In contrast, EEG reactivity was markedly impaired in delirious patients, with only 22% showing normal reactivity compared to 71% in non-delirious patients (p<0.001). Conclusions: In critically ill patients, sleep did not differ between patients with delirium versus no delirium. However, the presence of delirium was associated with impaired cortical responsiveness, as reflected by altered EEG reactivity. These findings suggest that EEG-based sleep monitoring and reactivity assessment may provide valuable insights into acute brain dysfunction in the ICU and help identify patients at risk of delirium. Further studies are needed to investigate whether interventions aimed at restoring sleep architecture and cortical activity could mitigate delirium and improve patient outcomes.