The available evidence indicates melatonin may decrease the incidence of delirium in non-critically ill patient populations; however, trials in the critically ill are lacking. The investigators hypothesize that melatonin, administered on a scheduled nightly basis during ICU admission, will be efficacious and safe for the prevention of delirium in critically ill adults. The null hypothesis is that there is no difference in delirium incidence between placebo and melatonin. Prior to conducting an adequately powered multi-centre, blinded randomized, placebo-controlled trial in critically ill patients, there is a need for a better understanding of melatonin pharmacokinetics (PK) in critically ill patients. This will help to determine appropriate dosing, drug administration issues (specifically protocol adherence), adverse drug effects, and recruitment rates based on inclusion and exclusion criteria.~The specific aim is to conduct a phase II triple blind, placebo-controlled randomized trial comparing two doses of melatonin (low dose = 0.5 mg and high dose = 2.0 mg) to assess the feasibility of a future full-scale RCT. Feasibility of the larger trial will be based on protocol adherence and participant recruitment rates. Data on PK properties of melatonin will be assessed to determine dosing for future studies of melatonin for delirium prevention in the critically ill.
The purpose of this study is to determine the feasibility of conducting a randomized controlled trial (RCT) with melatonin for prevention of delirium in critically ill adult patients. The investigators hypothesize that melatonin, administered on a scheduled nightly basis during ICU admission, will be efficacious and safe for the prevention of delirium in critically ill adults.