Meghan, 23, began experiencing hallucinations at 19. "Driving home, cars' headlights turned into eyes. The grills on the cars turned into mouths and none of them looked happy. It would scare the crap out of me," Meghan says. Marvi Lacar for NPR hide caption

itoggle caption Marvi Lacar for NPR

Dr. Allan Ropper speaks with residents and fellows as they do rounds at the neuroscience intensive care unit at Brigham and Women's Hospital in Boston. M. Scott Brauer for NPR hide caption

itoggle caption M. Scott Brauer for NPR

In this image taken from video on Jan. 15, police officers Edward Sarama (from left) and Robert McGuire try to talk to officer Matt Dougherty, who is pretending to be mentally ill, during a training simulation at Montgomery County Emergency Service in Norristown, Pa. Michael Rubinkam/AP hide caption

itoggle caption Michael Rubinkam/AP