An earlier study looked at the effect of the ICU admission on memory problems. The researchers found that the ICU setting and the medications given to many ICU patients can lead to delirium, sleep disturbance, and often a period of amnesia for the duration of hospitalization—greatly distressing for someone trying to recall and make sense of a traumatic experience. In addition, the medications given for sedation and pain control (especially in the ICU circumstance of physical constraint and social isolation) may increase hallucinations, nightmares, and paranoid delusions—all very hard to separate from reality after a patient has physically recovered.