Melatonin for Treatment of Delirium in Critically Ill Adult Patients

Inclusion Criteria: * Patients aged 18 years or older admitted to the intensive care unit; * Anticipated ICU stay \> 48 hours; * ICDSC score greater than or equal to 4 for a maximum of 48 hours prior to randomization. Exclusion Criteria: * Known allergy or hypersensitivity to melatonin or to ingredients in ORA-BLEND SF®; * Use of melatonin within 24 hours prior to randomization; * Presence of severe structural brain injury (intracranial hemorrhage or traumatic brain injury), severe major neurocognitive disorder, advanced neurodegenerative disease or hepatic encephalopathy; * Diagnosis of schizophrenia, bipolar affective disorder, psychotic depression, uremic encephalopathy or alcohol withdrawal; * Presence of active seizures, coma, aphasia or severe intellectual disability; * Limited short-term vital prognosis; * Diagnosis of delirium prior to ICU admission; * Pregnancy or breastfeeding; * Absolute contraindication to receive enteral medication; * Inability to understand or speak English or French; * Total blindness.