“Sweet dreams,” we say at bedtime. But why do we dream at all? And what happens when we’re plagued by nightmares? Michelle Carr is director of the Dream Engineering Laboratory in the Center for Advanced Research in Sleep Medicine, an assistant professor at the University of Montreal and a former president of the International Association for the Study of Dreams. She joins guest host Courtney Collins to discuss the sleeping mind, how to move past nightmares to a more restful night and how we can even take control of our dreams. Her book is “Nightmare Obscura: A Dream Engineer’s Guide Through the Sleeping Mind.”