Why Do We Dream? Three Modern Theories on Sleep

From a lecture series presented by Professor Mark Leary, Ph.D.

Why do we dream? Modern theories of dreams suggest that dreams are functional—that they do something useful for us. One functional theory suggests that dreams help people to solve personal problems, to find solutions to things in life that are bothering them.

Why do we dream?  Exploring what makes us dream.

This is a continuation of Why Do We Dream? From Freud to Activation-Synthesis Theory

The Problem-Solving Explanation of Why We Dream

So, if we are struggling with problems at work or in a relationship, our dreams explore these problems as we sleep and sometimes hit upon a solution for us. When people say that they are going to “sleep on” a problem, they mean that they hope that an answer will come to them while they’re sleeping.

Learn more: Solving Psychological Mysteries

The “problem-solving explanation” for why we dream sounds quite plausible, but it doesn’t really square with a good deal of research either. For example, less than half of the dreams that people report have any connection, however remote, to the events they experienced the previous day, and even far fewer seem to have anything to do with people’s current problems.

Furthermore, the fact that people recall only a very small percentage of their dreams—perhaps as low as 1 percent—also argues against the problem-solving theory. It wouldn’t make much sense to have a process that helped us figure out solutions to our problems but that didn’t let us remember the solutions that dreaming provided!

…research doesn’t show differences in well-being between people who do and do not remember their dreams.

And, if dreams help us with our problems, then it would seem that people who remember their dreams would be at a great advantage in life compared to people who don’t recall many of their dreams each night. But research doesn’t show differences in well-being between people who do and do not remember their dreams. People who recall more of their dreams don’t seem to resolve their personal problems more effectively. So, although there’s plenty of evidence that many dreams do reflect our daily problems, there’s not much support for the idea that dreaming helps us figure out useful solutions.

Learn more: Where Do People’s Personalities Come From?

The Cleanup Explanation for Dreaming

Other theories of dreaming focus on what the brain is doing when people dream, and these explanations don’t require that people remember their dreams in order for the process to be beneficial. For example, one theory suggests that dreams are involved in the process of “cleaning up” recent memories and other clutter from the mind.

I have a program on my computer that I run from time to time that deletes redundant files, clears out fragments of files I don’t need any more, erases traces of Internet surfing, and generally cleans up the clutter on my hard drive so that it operates more efficiently.


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In the same way, some experts suggest that while we sleep each night, this kind of cleaning operation occurs in the brain. The images in our dreams are just snippets of memories that are being scanned and evaluated for deletion, thereby cleaning up the mind to prepare for the next day.

Like the other theories, the cleanup explanation makes sense, but not everything that we know about dreaming supports it. As I mentioned, only about half of our dreams involve anything related to our recent experiences, so it’s not clear that our dreams reflect recent memories that are being scanned and deleted.

And, in addition, the cleanup explanation would seem to predict that our dreams would be composed of little piecemeal snippets of memories, but they usually aren’t. Dreams often have an internally consistent story line that doesn’t have any obvious connection to anything that actually happened to us recently.

Learn More: Why Do We Have Emotions?

Why We Dream: The Consolidation Theory

A similar explanation known as consolidation theory suggests that dreams are involved in the storage of memories from the previous day. When we talked about forgetting, I mentioned that memories undergo a process of consolidation that helps to store them in long-term memory. And some researchers believe that dreaming occurs each night during the consolidation process.

This is another explanation in which the content of a dream is just a by-product of brain activity that’s occurring as memories are consolidated.

This explanation has many of the same problems as the cleanup theory. When researchers analyze the content of people’s dreams, they don’t often seem to involve actual memories like the theory would predict.

Well, as you’re starting to see, researchers have offered many reasonable explanations of what dreaming is all about, but none of them are entirely consistent with the data that research has provided about sleep and dreaming.

Perhaps that means that we haven’t yet uncovered the real purpose of dreaming, or maybe it means that dreaming doesn’t actually have a function, or maybe we’re asking the wrong questions.

Another approach to understanding dreaming is to examine the content of people’s dreams. People tend to dream about certain topics far more than other topics.

Most people have had dreams of being naked or dressed inappropriately in public, or running in terror from something that was chasing them. But not many of us have had dreams of doing pushups in an airplane or picking grapes. Maybe that tells us something.

Read about why dreams are so weird in part three of this series of articles on dreams.
From The Lecture Series Understanding the Mysteries of Human Behavior
Taught by Professor Mark Leary, Ph.D.

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