Objectives: Nonpharmacologic delirium management is recommended by current guidelines, but studies on the impact of ICU design are still limited. The study's primary purpose was to determine if a multicomponent change in room design prevents ICU delirium. Second, the influence of lighting conditions on serum melatonin was assessed.

Design: Prospective observational cohort pilot study.

Setting: The new design concept was established in two two-bed ICU rooms of a university hospital. Besides modifications aimed at stress relief, it includes a new dynamic lighting system.

Patients: Seventy-four adult critically ill patients on mechanical ventilation with an expected ICU length of stay of at least 48 hours, treated in modified or standard rooms.

Interventions: None.

Measurements and main results: The clinical examination included a prospective assessment for depth of sedation, delirium, and pain every 8 hours using validated scores. Blood samples for serum melatonin profiles were collected every 4 hours for a maximum of three 24-hour periods. Seventy-four patients were included in the analysis. Seventy-six percent ( n = 28) of patients in the standard rooms developed delirium compared with 46% of patients ( n = 17) in the modified rooms ( p = 0.017). Patients in standard rooms (vs. modified rooms) had a 2.3-fold higher delirium severity (odds ratio = 2.292; 95% CI, 1.582-3.321; p < 0.0001). Light intensity, calculated using the measure of circadian effective irradiance, significantly influenced the course of serum melatonin ( p < 0.0001). Significant interactions ( p < 0.001) revealed that differences in serum melatonin between patients in standard and modified rooms were not the same over time but varied in specific periods of time.

Conclusions: Modifications in ICU room design may influence the incidence and severity of delirium. Dedicated light therapy could potentially influence delirium outcomes by modulating circadian melatonin levels.