Most of your dreams happen in REM sleep. You're body is still, and you mind is active. But if you have REM behavior disorder (RBD), you act out your dreams, which can be violent and vivid. In this episode of NewsMD's "Health Fusion," Viv Williams talks to someone who has this disorder. And she hears from a neurologist who, with a team of experts around the nation, started a new study to research the condition because it is associated with other diseases, such as Dementia with Lewy Bodies and Parkinson's Disease.