<qa>  What is the maximum amount of time for the capsules to be administered?Within 24 hours of admission to the floor, study subjects will be approached by a member of the research team, and asked for informed consent. Patients that consent to participate will be randomized to either the treatment or the placebo arm. Each subject will be administered a capsule containing either placebo or 5 mg melatonin each evening at 9 p.m. The capsules will be prepared and administered by the Yale-New haven Hospital Investigational Drug Service. The capsules will be administered nightly until discharge or a maximum of 2 weeks, if the hospitalization is prolonged. 