Our dreams can haunt us: literally. Recurring dreams about failing tests or running late are a common occurrence, but what are we to make of them? And are there hidden meanings in our dreams? Paleolithic hunter-gatherers may have painted their dreams onto caves, Julius Caesar's wife envisioned his assassination in a dream, and major works of art and music have been inspired by dreams. But with the scientific revolution came a different view of dreams, one in which they were dismissed as merely a meaningless biological reaction. Today, researchers are challenging that age-old assumption and finding new evidence that dreams are a vital way human beings process the world. In this episode, Sidarta Ribeiro takes us on a journey through the history of our understanding of dreams.