Curiosities: Why do we dream?

Following Sigmund Freud, many people used to believe dreams were a way of dealing with thoughts and issues that were too painful or bizarre to confront during waking life. From this idea, the entire field of dream interpretation emerged.

Most scientists no longer believe this, though. “The truth is, we don’t really know why we dream,” says Brady Riedner, a researcher with the UW–Madison Center for Sleep and Consciousness. “What we do know is that during dreaming sleep, the brain is just as active as it is during waking, but in a different way.”

He explains that because the sleeping brain is mostly disconnected from the rest of the world, its activity can be more spontaneous, bouncing around to any number and combination of thoughts, in no apparent logical order. That’s why dreams – though seemingly very real – tend to progress in weird and unpredictable ways.

At the same time, dreams aren’t totally random. They often relate to events and thoughts from waking life. Why? Scientists know the brain’s structure is shaped by the stimuli it takes in while awake; for example, thoughts and experiences are known to strengthen the connections between certain neurons. Dreams, therefore, might merely be echoes of these daytime changes.

Another hypothesis says that the activity of the dreaming brain serves to modify the brain further. Sorting this out is one of the big goals of current sleep research, says Riedner.