IRCT2015022421159N1 IRCT 2015-06-13 Vice chancellor for research, Isfahan University of Medical Sciences The effect of melatonin on delirium prophylaxis The effects of melatonin versus placebo on delirium prophylaxis in patients hospitalized in intensive care unit of Alzahra hospital, Isfahan, 2014-2015 2014-12-22 anticipated 140 Complete https://irct.ir/trial/18606 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention, Other design features: The random number generator is used in our study to assign each patient randomly in intervention or control group (Randomized clinical trial). The random numbers were given by a study coordinator, who also encodes the drugs with matching random numbers. In addition, we formulate placebo with the same appearance to melatonin tablet. Therefore, neither the patients nor the researchers evaluating the study outcome know which patient is receiving melatonin or placebo, until the study is over and the random code is revealed. N/A Delirium. Intervention 1: Intervention: Melatonin (Nature Made), tablet 3 mg, once daily (21:00 AM), orally for 5 consecutive days. Intervention 2: Control group: Placebo (consists of tricalcium phosphate, magnesium stearate and starch glue which is made in pharmacy faculty of Isfahan University of Medical Sciences), once daily (at 21:00 AM), orally, for 5 consecutive days.