Why do we dream?
  The expectation fulfilment theory of dreaming
sleep and dreams

The expectation fulfilment theory

Dreaming is Nature’s solution to the problems emotions cause animals and humans. (An emotion is another word for an expectation.) Stress, for example, is caused by an accumulation of arousal patterns in the autonomic nervous system that are not being dearoused by taking the necessary actions that would do so.

The prime function of dreams is to metaphorically act out undischarged emotional arousals (expectations) that were not acted out during the previous day. By dreaming we complete the arousal/dearousal circuit so as to wake up with an unstressed autonomic nervous system and our instincts intact.

If we have happy positive expectations we have happy dreams, but, when this system is overstretched and the dreaming process cannot cope with the amount of negative expectations (as when people continually worry), sleep balance is disturbed, dreams are miserable, even nightmarish, and depression can set in. An extreme stress overload can interfere with the process to such an extent that psychotic symptoms arise (schizophrenia is waking reality perceived through the dreaming brain).

This is the first viable theory of why we evolved to dream. It offers a holistic synthesis of the interdependence of biology and psychology that explains the evolutionary origin of dreaming and what it actually does for us every night. Since its publication in 1993 it has not been contended.

How the theory arose

Prompted by the recognition that one of his own dreams was a metaphorical translation of something that happened the previous day, Joe Griffin set off on what was to become a twelve-year research programme. During this time he carefully reviewed all the available scientific evidence about dreaming together with the competing theories put up to explain it, as well as conducting much original research of his own (detailed in full in the best-selling book: Why we dream: the definitive answer).

Strangely, at a point where he was about to give up on his quest to solve the mystery of why dreaming evolved, he made a startling breakthrough. All the pieces of the jigsaw suddenly fell into place and he realised that dreaming dearouses the autonomic nervous system every night from all the patterns of emotionally arousing expectations that are not acted out when we are awake. He called this theory the expectation fulfilment theory of dreams.

Before stumbling across the bigger picture he had shown that all dreams are expressed in the form of sensory metaphors and the reason for this is found in the biology of the rapid eye movement (REM) state, a special brain activation that all mammals go into.

Research in France by Michel Jouvet had already indicated that instinctive behaviours are programmed during the REM state in the foetus and the neonate but Griffin took this further. He realised that this programming is necessarily in the form of incomplete instinct templates for which the animal later identifies analogous sensory components in the real world.

These analogical templates give animals the ability to respond to the environment in a flexible way and generate the ability to learn, rather than just react. We can see this process beautifully when a baby seeks out and sucks on anything analogous to a nipple, like a finger or rubber teat.

Once an instinct-driven pattern is activated and becomes an expectation it can normally only be deactivated by the actual carrying out of the programmed behaviour by the central nervous system. Although instincts are 'hard-wired' in us, this process alone clearly does not give us the flexibility we need to survive because if we acted out every arousal there would be chaos.


All emotions derive from expectations. When an expectation is 'set up' the autonomic arousal system raises an emotion to provide the necessary energy to get the expectation met. Only when the expectation is fulfilled is the autonomic nervous system dearoused. If this complete ‘arousal/dearousal’ process does not happen whilst we are awake, it is 'deactivated' metaphorically in a dream. This has to happen otherwise our instincts would be conditioned out of us.

This is one of those scientific observations that needs no special equipment to test, anyone can easily check it out for themselves. If our boss makes us feel angry and we express our anger at them, the anger is dissipated. But, if we suppress the anger, it is metaphorically expressed in a dream. The reason we often have to suppress our feelings is that, if we were to act them out, at our boss every time he made us angry for example, that would be disastrous: we would be fired.

So dreaming evolved because animals needed to the ability to inhibit arousals when necessary, leaving them to be deactivated later when they could do no harm.


The brain is constantly matching patterns, asking in effect, "what is this incoming sensory information like?"  It is continually comparing and contrasting the incoming data it receives for similarities with innate instincts or memories so it can know what to expect. It has to do this in order to decide how to act. This is known as 'metaphorical pattern matching' and is why the unfulfilled emotional expectations left over from the day are run out in the form of metaphors in dreams during REM sleep.  Without this happening the brain would not be freed up to deal with any new emotionally arousing events the following day.

There are good reasons why all dream content is metaphorical and not directly about the concerns of the day. Firstly, the brain cannot generate "real world" reality without feedback from the environment. So, since all our senses are switched off whilst we are dreaming, instead of the brain seeking to fulfil the patterns of arousal externally, it does so internally, drawing on memories that have emotional and metaphorical resonances with the unresolved arousal patterns in the autonomic nervous system.  This is why dreams often seem so odd; they draw on memories and images from your entire life, even though they are only about unacted out arousals from the previous day. So every person you see in a dream is standing in metaphorically for someone else in real life.

Secondly, without using metaphorical translations the brain would either be forced to create false emotional memories or be left with massively significant gaps in memory.

In the first case if the brain acted out unexpressed waking expectations and committed that experience to memory it would have created false memories. It could, of course, be argued that we have the ability to distinguish dreams from waking reality. But that would be missing the point. The emotional conditioning of our reactions would have still taken place even if we were subsequently able to separate dreams from real memories.  Just as someone with a phobia of spiders, who knows intellectually that they are not a real threat to them, still has the emotional conditioning triggered off and scream whenever they see one.

On the other hand, if the brain chooses to forget the dream (which is what happens) it would create gaps in memory for what actually happened since the dream will involve both real and fantasy experiences. This would be equally disastrous because a memory system with significant memories missing would be next to useless as a basis for predicting the future, as is the case with people suffering from Alzheimer’s disease.  By using analogy or metaphor whilst dreaming the brain can discharge the arousal, safely forget the metaphorical dream material and keep the original record of what really happened filed away in memory.

The expectation fulfilment theory of dreaming summarised

Dreaming is the deepest trance state we go into and there are three essential principles to understand:

  • Dreams are metaphorical translations of waking expectations.
  • But only expectations that cause emotional arousals that are not acted upon during the day become dreams during sleep.
  • Dreaming deactivates that emotional arousal by completing the expectation pattern metaphorically, freeing the brain to respond afresh to each new day.

Video — Why we evolved to dream: the new understanding

The veracity of the theory

The expectation fulfilment theory of dreaming was first published in the peer reviewed journal The Therapist (1993), forerunner of the Human Givens Journal, and, despite wide exposure, has not been successfully contended.

It unifies many previously unexplained phenomena (detailed in Why we dream: the definitive answer) and predictions deriving from it have been shown to be true. In addition, the theory now stands at the heart of a new school of psychology known as ‘human givens’..

The theory’s practical applications, particularly with regard to treating mental illness, give support to its veracity. (No other theory of dreaming has produced practical applications.) In addition it led to the first straightforward explanation for hypnotic phenomena and the symptoms of schizophrenia.

Since it was first published it has received much support from psychologists, brain researchers and interested members of the public from whom we welcome further ideas and comments on the subject. Please send them to us.

Applications of the theory >

As mentioned above, a full account of the history of Joe Griffin's research appears in Why we dream (pages 21-48: 'An experimental adventure').

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Why we dream book

For the full story of Griffin's
ground-breaking research,
including all references, see:
Why We Dream:
The definitive answer



> Summary of the theory

> How this theory explains other
   research findings that other
   dream theories cannot

> What about lucid dreams?

> Dream Examples

Practical applications of the theory

How to interpret your own dreams

> Responses to the theory



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© Copyright Joe Griffin and Human Givens Publishing Ltd. 2007