Dr. Zeev Kain, anesthesiology & perioperative care professor and chair at UC Irvine, has found that treating children with the hormone melatonin before they undergo surgery significantly reduces emergence delirium, a distressing incidence of acute behavioral changes experienced when waking up from anesthesia. Affecting up to 20 percent of children who undergo surgery, emergence delirium in the post-anesthesia care unit can include crying, thrashing and need for restraint. This also can lead to behavioral changes outside the recovery suite, with the onset of nightmares, bed-wetting and separation anxiety, according to Kain. Melatonin is a hormone that regulates sleep and moods. The study, which involved 148 subjects between the ages of 2 and 8 undergoing outpatient surgery, appears in Anesthesiology.