Psychedelic therapy has shown great promise for treating depression, but it's still unclear why exactly it works. Psychiatrist Charles Raison wants to know if it's the drug or the trip that makes psychedelics so potent. Is it biology or consciousness? In one of Raison's studies, psilocybin is being injected into people in deep sleep. So, will they feel better when they wake up even if they have no memory of the experience?