Doctors often tell patients going under anesthesia that they're going to sleep. But recent research suggests it's actually more like going into a short-term coma. But the causes of low brain activity are different in sedation and coma. Ausim Azizi, head of the neurology department at Temple's School of Medicine, said that difference limits the usefulness of drawing connections between coma and sedation. "The EEG patterns may be close to anesthesia," Azizi said. "But the pathology, or the molecular mechanisms of what happens to the brain, is not similar."