Your brain isn't the only organ processing your day while you sleep. Dr. Emeran Mayer explains the circular processing of emotion and memory that goes on between your brain and your digestive system, and how the latter can "dream".
Neuroscientists now think of the gut as a "second brain"; it independently controls your digestive processes and is in constant conversation with your main brain. What do they talk about? Depression, theorizes Dr Emeran Mayer.