Hallucinogenic drugs--popularly called psychedelics--have been used by human societies for thousands of years. Today, scientists are taking a second look at many of these mind-altering substances--both natural and synthetic--and discovering that they can have profoundly positive clinical impacts, helping patients struggling with a range of afflictions from addiction to depression and PTSD.

Originally released by PBS, 2022. Streaming video file encoded with permission for digital streaming by Infobase on October 31, 2022.