Targeted Sedation And Circadian Interventions In Mechanically Ventilated ICU Patients: A Narrative Review

Circadian rhythms regulate sleep-wake cycles, hormone secretion, immune functions, and cardiovascular activity. However, they are frequently disrupted in mechanically ventilated ICU patients due to critical illness, environmental factors, and sedative exposure. This narrative review aims to examine the interaction between sedation practices, environmental interventions, and circadian disruption. A structured, non-systematic search of MEDLINE/PubMed, Web of Science, and Scopus (200-2025) was performed to identify mechanistic and clinical studies. Evidence indicates that deep and prolonged sedation is associated with decreased melatonin secretion, disrupted sleep architecture, and increased delirium risk, whereas minimal sedation combined with circadian-aligned non-pharmacological interventions, such as light and noise modulation and care clustering, may support organization. However, findings remain conflicting and are largely derived from observational studies. The use of a combined sedation-circadian rhythms care strategy represents a novel, untested approach. Future studies should incorporate standardized circadian outcomes and controlled designs to establish causality and evaluate clinical efficacy.