Why Do We Dream? The Top Theories Explained

a woman dreamingWhen was the last time you woke up with a powerfully clear memory of a vivid dream on your mind?

Have you ever woken up and felt utterly compelled to share an incredible, or perhaps scary, dream with someone over breakfast?

You spend around a third of your life sleeping, and a sizable chunk of that time dreaming. So it makes sense to wonder why you have dreams, and if they mean something or not.

In this article I’ll be looking at some classic and current theories about why we dream. Scientists and researchers still don’t agree on any one theory, of which there are many.

So for now it’s a case of looking through and deciding which theory, or combination of theories, makes most sense to you.

Poll results

In 2016, I asked readers about their dream recall and content. In the graphs below you can see that the majority of readers regularly remember their dreams. And that the most common dreams are either about people – or simply random and weird.

graph showing the results poll asking readers how often they remember their dreams
graph of the results of a poll about what type of dreams readers have

Do we dream every night?

Before looking at why we dream, it’s interesting to consider just how often we dream. You might be surprised to find out that you probably dream much more than you realize.

The answer to the question of how often you dream lies in some ground-breaking and famous 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 is now known as REM sleep.

They found that people regularly had rapid eye movements (REMs) during their sleep. They were also the first to discover the key fact that the brain remains active during sleep.

Importantly, they found that if people were woken during the time they were in REM sleep, they would report that they were dreaming in around 95% of cases. And if they were woken up during non-REM sleep, they reported they were dreaming in 5-10% of wakings.

We now know that we 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% to 25% of sleep, occurring in four to six separate episodes.

The first cycle of REM sleep might only last between 1 and 5 minutes, but by the end of the night we might spend up to an hour during a REM stage.

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

Whether you remember your dreams when you wake up or not is a different matter altogether though. You can read more about the sleep stage timings here.

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 why we dream.

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

These were the prevailing dream theories for years, and were also a major influence on the popular world of dream interpretation.


Freud believed that our dreams are a form of wish fulfillment. They are a disguised fulfillment of repressed wishes, just waiting to 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 later also spoke about how trauma and aggression also influence our dreams.


Jung’s theory moved away from Freud’s wish fulfillment idea and proposed that dreams were expressions of unresolved issues.

He felt that dreams clearly 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. This 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

We know from sleep researchers that there’s a lot of brain activity when we sleep; the brain definitely doesn’t completely shut down at night.

In an attempt 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, and in some ways still is, a controversial theory. Especially at the time when it appeared to challenge Freud’s ideas about dreams being secret desires. Nonetheless, it has stood the test of time and is still a very popular theory.

Hobson and McCarley argued that during REM sleep, specific areas of the brain are activated, such as the amydala 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 synthesize and interpret the activity, resulting in dreams.

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

Hobson, however, didn’t state that dreams should be ignored as useless and random. He thought dreams were a creative state and that whilst mostly nonsense, some products of dreams could be useful.

Perhaps a great example of that would be 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 teenage dream.

Sadly though, the examples of key discoveries or works of art arising in dreams, whilst fascinating, are few and far between. Interestingly, it’s also been suggested that external stimuli can influence the dreams, such as temperature or sound.

Perhaps that’s why we might hear an alarm in our sleep, which then gets transformed into a dream about a fire engine. Then if you wake up and hear the real alarm, you might think how strange it was that you were just dreaming about hearing an alarm too!

Needless to say though, if you’re the kind of person who likes to think dreams have some 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 famous, but again slightly controversial theory, is that the brain does a form of spring cleaning and reorganizing during REM sleep, with dreams occurring due to this.

In 1983 Crick and Graeme first put forward this view, comparing the brain to a computer organizing itself in a kind of ‘off-line’ mode.

The idea being that the brain is both throwing out unnecessary memories acquired during the day, and connecting the useful ones. A little like a computer defragmenting.

Other research though suggests that in fact the brain consolidates memories and processes information, rather than being more concerned with discarding memories.

4) Information processing and memory consolidation

One of the major theories about why we sleep at all is the information consolidation theory of sleep. This theory proposes that we sleep in order to process the incredible amount of information our brains acquire during the day.

And that this sleep time also helps to prepare us for the following day and what we need to do. It’s an important time when experience and learning is solidified into long-term memories to be used in the future.

Some researchers have proposed, such as Jessica D. Payne and Lynn Nadel in 2004 that dreams reflect the biological processes at work during this complex memory consolidation.

And Erin J. Wamsley and Robert Stickgold in 2011 further suggest that our brains rehearse things we learn during the day during sleep to consolidate it, and dreams reflect this replay of memory. They also propose that rehearsing during sleep may increase performance the next day.

Whether or not dreams are a by-product of the information processing or play an active part still remains to be proven though.

5) Threat rehearsal and simulation

A popular evolutionary psychology theory of dreaming proposes that dreams arise from our brains practicing skills, decisions and actions we need to survive.

In an article in psychology today in 2007, research at the University of Wisconsin was neatly used as an example of how dreams perform this function.

Experiments with rats deprived of REM sleep appear to show that without the ability to rehearse survival strategies in their dreams, they simply don’t behave in the way that’s best for them during tests.

Applying that theory to humans helps explain why some of the most common dreams involve being chased or attacked, with negative emotions like fear and anger. We use dreams as a theater to practice things which we might need one day, but simply can’t or don’t practice during the day.

This theory is also held by the Finish psychologist Antii Revonsuo who proposed in his 2000 research paper that dreaming was essential in ancestral times for daily survival, and therefore evolutionary success.

He found that people dream of threats and have nightmares far more often that we previously thought. Dream diary experiments apparently show that we have between 300 and 1000 nightmares per year on average!

Here is a quote from the conclusion of his paper summarizing his view:

The hypothesis advanced in the present paper states that 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.

To read about this theory in more detail, have a look at the Psychology today article.


6) problem solving

In some ways related to the threat rehearsal theory is the idea that sleep and dreaming helps us solve problems. Though threat is clearly a major feature of dreams, we aren’t always engaged in such high energy and emotional dreams.

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

Researchers such as Deirdre Barrett at the Harvard medical school have even proposed that we can train ourselves to influence our dreams to help us solve problems we want to work on. There is no conclusive evidence as yet that this is possible, but it’s certainly an appealing idea.

You can find out more about the current research into problem solving during sleep in this article.

7) Dreaming eases painful memories

In 2011 research at Berkley University was widely published in the media about how sleep can help ease painful memories. And specifically they talked about the chemical changes in the brain occurring during sleep and the association with processing memories.

Perhaps this helps explain why we sometimes feel a little better after a good night’s sleep when we are upset about something that happened. For more on this theory, you can read the article by the BBC .

Christian and Islamic dream interpretation

Historically, dreams were often interpreted as having some religious or spiritual significance. There are numerous biblical references to predictive dreams, such as Joseph dreaming about Mary’s immaculate conception.

And in the first 3 centuries AD religious authors such as Clement, St. John Chrysostom and Augustine wrote that dreams could be important in one of two ways:

  • Dreams could be predictive, as was sometimes thought the case with important christian figures who received messages regarding the present or the future.
  • Dreams could be a space in which the person could experience a meaningful connection with God or other entities such as angels.

Whilst the role of dreams is not defined in the modern day by the christian faith, there are accounts of some cultures still believing that dreams still can convey messages from God.

For example, Werner Nell at North-West University, South Africa published an interesting article regarding the beliefs of South African Christians which you can read here.

Dreams are also still thought to be important in some Islamic cultures. Some Muslims pay particular attention to their dreams, using them as a part of their daily decision-making process. For more on that, have a look at Iain R. Edgar’s book “Dreams in Islam“.


As I said at the start, there’s unfortunately no theory about dreaming which everyone agrees on. What’s clear is that it’s an on-going area of major interest for scientists in a range of fields, with new research regularly appearing.

Perhaps one day the disciplines will unite around one theory. But it seems unlikely for some time to come.

So it’s perhaps down to the individual to make their own decision as to what they choose to believe for now. Personally, all of the theories hold a certain appeal to me for different reasons.

I’d prefer not to see dreams as completely random, and quite like the idea that they’re my brain continuing to think, albeit in a different state. I also like the idea that nightmares might actually be useful and are preparing me for possible problems in the future.

I wonder if there’s a way this concept could be passed on to children who struggle with nightmares to help them see them in a different light and not fear them so much.

Your views

Why do you think we dream? Which theory makes the most sense to you? Feel free to share your opinion and thoughts in the comments below.

4 CommentsLeave a comment

  • 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!

    • 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!

  • 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.

    • 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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