Melatonin to prevent delirium in the ICU: revisiting the evidence

Delirium is a challenging complication of critical illness, affecting up to 80% of patients after intensive care units (ICUs) admissions, regardless of aetiology [1]. It contributes to prolonged hospitalization and negative outcomes. Research on its prevention and treatment spans from definition to patient selection, assessment tools, through challenges of specific motor subgroups (e.g. hypoactive delirium), and addressing causative conditions and risk factors [2]. Clinicians and researchers have long searched for strategies to prevent or mitigate delirium. Melatonin, an endogenous regulator of circadian rhythm with neuroprotective and anti-inflammatory properties, was appealing, and supported by recent guidelines [3]. Yet, the meta-analysis by Lakbar and colleagues, published in a recent issue of ICM, [4] challenges previous assumptions and reopens the discussion on whether melatonin can prevent delirium or reduce mortality in critically ill patients.