a woman dreamingHow often do you remember your dreams in the morning? Do they tend to be fairly boring, adventurous or scary?

You spend around a third of your life sleeping, and a sizable chunk of that time dreaming.

So it makes sense to wonder where those dreams come from, and if they have any hidden meaning.

Scientists don’t agree on one explanation, and there are several theories. So in this article, we’ll take a look at the main ideas.

Dream poll results

I asked 300 readers about their dreams. In the charts below, you can see that the majority regularly remember their dreams. At least the ones interested in reading about dreams do!

Interestingly, the most common dreams were either about people or ‘random and weird’.

poll results about how often readers remember their dreams
chart showing the poll results about the activities people commonly dream about

Does everyone dream every night?

The answer to the question of how often you dream lies in some groundbreaking sleep research conducted more than 60 years ago.

In 1953, a student at Chicago University called Eugene Aserinsky and his adviser Nathaniel Kleitman discovered what’s now known as REM sleep.

They found that people regularly had rapid eye movement (REM) during their sleep. And if people were woken during that REM sleep, they reported dreaming in around 95% of cases.

And if they were woken up during non-REM sleep, just 5-10% of people reported dreaming.

Interestingly, they were also the first to discover that the brain is actually very active when you sleep.

Dreaming during REM sleep

You cycle through different sleep stages during the night, and enter into REM sleep several times on average.

During the night, REM sleep usually accounts for 20-25% of your sleep time, occurring in four to six separate episodes.

The first cycle of REM sleep might only last a few minutes. But by the end of the night, you might spend up to an hour during a REM stage.

So statistically it’s assumed that the majority of people dream most nights. And researchers believe that we have on average of 2-6 dreams per night.

Whether you remember your dreams is a different matter altogether though.

The main theories

1. The psychoanalytic theory: wish fulfillment and unresolved problems

Two of the most famous psychiatrists in history, Sigmund Freud and Carl Jung, both had interesting theories about dreaming.

Even though their ideas are largely dismissed by many psychologists and neuroscientists, they still prove popular among some psychoanalysts.

These were the prevailing dream theories for years, and led to the development of dream interpretation.


Freud believed that our dreams are a form of wish fulfillment. They are a disguised fulfillment of repressed wishes, and can be analyzed for deeper meaning.

He believed dreams represent our unconscious desires, wishes, and thoughts. So in our sleep, we play out fantasies or unconscious wishes, often related to childhood.

Initially, he said that much dream content was sexual in nature. But he later also spoke about how trauma and aggression influence dreams.


Jung proposed that dreams were expressions of unresolved issues. He felt they revealed which emotional problems, worries and fears we needed to be aware of, and address.

The idea was that these dreams tell us which parts of our psyche, or personality, are out of balance. That can then help us work towards psychological development and integration.

dream about a couple in love
Could dreams represent our unconscious desires or unaddressed issues?

2. The activation-synthesis theory

To understand the role that brain activity plays in dreaming, J. Allan Hobson and Robert McCarley in 1977 proposed the activation-synthesis theory of dreaming.

It was a controversial theory, especially as it challenged Freud’s ideas about dreams being secret desires. Nonetheless, it has stood the test of time and is still a popular theory.

They argued that during REM sleep, specific areas of the brain are activated, such as the amygdala and hippocampus.

These areas are involved in emotions, memories, and sensations. So they proposed that when they are activated during sleep, the brain tries to interpret the activity, which creates dreams.

It’s as if dreams are the result of the brain trying to create meaning from random brain activity which occurs while we sleep.

Creativity when dreaming

Hobson didn’t think that dreams were completely useless though. He thought dreaming was a creative state, and that although mostly nonsense, some dreams could be useful.

Perhaps an example of that is Paul McCartney finding the tune to the famous Beatles song “Yesterday” in a dream. Or Albert Einstein coming up with his theory of relativity during a dream.

Sadly though, the examples of key discoveries or works of art arising in dreams are few and far between.

If you do believe dreams have meaning, or can be interpreted, the activation-synthesis theory isn’t the one for you.

random dream imagery
Are dreams just random images arising from random brain activity?

3. Reverse learning: tidying up the memory

Another slightly controversial theory is that the brain does some reorganizing during REM sleep. And dreams occur due to this mental ‘spring cleaning’.

In 1983, Crick and Graeme first put forward this view. They compared the brain to a computer organizing itself in an ‘offline mode’.

They proposed that the brain discards unnecessary memories acquired during the day, and connects the useful ones.

However, others suggest that the brain consolidates memories and processes information, rather than discarding memories.

4. Information processing and memory consolidation

One of the major ideas about why we sleep at all is the information consolidation theory.

This theory proposes that we sleep to process the incredible amount of information our brains acquire during the day.

Sleep also helps to prepare us for the following day. It’s an important time when experience and learning is solidified into long-term memories to be used in the future.

Jessica Payne and Lynn Nade proposed that dreams reflect the biological processes at work during this complex memory consolidation.

Erin Wamsley and Robert Stickgold further suggest that our brains rehearse what we learn during the day during sleep to consolidate it. And dreams reflect this replay of memory.

They also proposed that rehearsing during sleep may increase performance the next day.

Whether dreams are a by-product of information processing or play an active part still remains to be proven though.

5. Threat rehearsal and simulation

An evolutionary theory is that dreams arise from your brain practicing skills, decisions, and actions needed for survival.

Research at the University of Wisconsin illustrated this in a fascinating experiment with rats.

Rats were deprived of REM sleep, and therefore the ability to rehearse survival strategies in their dreams.

They were then given survival tests, and failed them – even when later given amphetamines to make up for sleep deprivation.

So perhaps people also practice important activities we might have to do, but can’t or don’t practice during waking life.


Antii Revonsuo, a Finnish psychologist, also proposed in a research paper that dreaming was essential in ancestral times for daily survival, and therefore evolutionary success.

He found that people have threat dreams and nightmares far more often than previously thought. Dream diary experiments showed that we have between 300 and 1000 nightmares per year on average.

Revonsuo concluded in his paper:

We dream (i.e., the phenomenal level of organization in the brain is realized in its characteristic ways during REM sleep) because in the ancestral environment the constant nocturnal rehearsing of threat perception and threat-avoidance skills increased the probability of successful threat avoidance in real situations, and thus led to increased reproductive success.


6. Problem solving

Although threat is clearly a feature of many dreams, we aren’t always engaged in such high energy and emotional dreams.

Researchers have also found that we’re better at solving problems after sleeping. And some research has specifically suggested that we’re only better at this following REM sleep.

Deirdre Barrett at the Harvard medical school has even proposed that we can train ourselves to dream about important problems we need to solve.

There’s no conclusive evidence as yet that this is possible, but it’s an appealing idea. You can find out more about these theories in this article.

7. Dreaming eases painful memories

In 2011, researchers at Berkeley University suggested that sleep, and dreaming, helps us deal with traumatic experiences.

They showed people images that provoke emotions and measured their response. Some were then allowed to sleep normally, but others not.

When they saw the same images the next day, those who slept well didn’t react as strongly as those who didn’t sleep well.

They suggest that the brain processed traumatic events during REM sleep. And this allowed previously intense emotional experiences to be safely dealt with.

Perhaps this explains why we feel better after a good night’s sleep when something upsets us. For more on this theory, you can read the article by the BBC.


There’s no unifying theory about dreaming which all scientists agree on. Whether they are random byproducts of brain activity, or something useful we can tap into, remains to be seen.

So for now, it’s perhaps down to the individual to decide what to believe. Personally, all of the theories hold a certain appeal to me for different reasons.

I like the idea that my dreams are a sign of my brain making good use of the hours I spend asleep every night.

I also like the idea that nightmares might actually be useful, and are helping me prepare for possible problems in the future.

Your views

Do you remember your dreams, and if so, what do you dream about? Which theory makes the most sense to you?

Leave a comment below!

4 thoughts on “Why Do We Dream? The Main Theories Explained”

  1. Brasilio Castilho

    Here is what I think. We dream for the same reason we get crazy, sad or smart. We are like a plucked string that generates harmonics. There is the main note (the “normal” self) and a great lot of surrounding notes, one of which can take over from time to time (the other selves).
    All the selves can talk to each other (this the origin of the so called inner voice). And there are all kind of selves, the good one, the bad one, the crazy one, the smarter, etc. When one of these takes over, your (the one you call your normal state, the your self) personality is changed. You are not you anymore.
    The main self is the mix result of all the selves. It is the mean around which all other selves are normally distributed. The greater the deviation from this mean, the greater the change in personality that people will notice in you. Yes, trauma, drugs and medicines can shift the self that is currently in control of your actions. The normal mean is displaced and a new mean takes over. Where are you now?
    Can you think of two different things at the same time? No, you cannot. You have to handle one of these things to one of your selves to take care of.
    If you fall in love with someone and you are a jet pilot that is trying to land the plane right now, you cannot (should not) think of your girfriend right now. But don’t worry (right now!), because one of your selves is taking care of that thoucht for you. After you land the plane, that self will handle you the thought of your girl friend and you can move ahead.
    What about that thought that keeps hammering in your head? And what about the sticky song that keeps singing in your head? No, its not you. It is one of your selves talking to you. Yes, boring persons have a lot of boring selves around them.
    As you can imagine when you are awake, so can all of your selves. Some of them go to sleep as you do, others don’t. When you fall asleep, many selves are still awake and, so, they can imagine things that you, even in sleep mode, can perceive and memorize. Then, after you awake, you say “Man, I had a really crazy dream last night”.
    Yes, we are not one, we are many!

    1. Hi Brasilio
      Thanks for your comment and very interesting theory! I’m not sure I totally agree with it, but metaphorically it makes some sense! And actually, I think that what’s been discovered is that we can generally do 2 things at once fairly well, but 3 is where it starts to become impossible to do properly. So I imagine more than one pilot in time has had thoughts of their partner pop into their head when they least want to!

  2. Personally, I’m very spiritual but I don’t believe in evil beings(I like good translations of hebrew), just that we humans have souls, some of us are good, some of us are evil. I think that some dreams are a way of telling us something but that we dont always understand. Some dreams may be teachings, some warnings, some just for fun or for fulfilling a need. I have lots of different types of dreams so it may well be that all of or most of the above interpretations you listed, are correct in some way. I have short dreams, long dreams, repeated dreams, lovely dreams, scary dreams, eureka moment dreams, dreams that feel so real its unbelievable, dreams that are very strange and dreams that shake me awake. A lot of dreams that feel and look different and are different types. I believe in god so I believe dreams are a way for him to show us things and the dreams that make no sense and are completely random, are what we get when he doesn’t show you anything.

    1. Hi there
      Thanks for your comment. I think you may be right in that there are different explanations for dreams, but perhaps they can co-exist. And perhaps as you suggest, sometimes different dreams might be serving a different purpose. I imagine it will be some time before researchers can define this with more accuracy, so for now we’re left to decide which theory works for us.

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