Tag Archives: Dreaming

Why Do We Dream?

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Key Dream Research Equipment

“What does my dream mean?!”

“Sorry…?”

“I’ve heard you study sleep. I mean I think I’ve worked it out myself but I wanted an expert opinion.”

“Erm…”

It doesn’t take long to drift into questions about dream analysis when I tell people that I study sleep. I don’t entirely blame them. It’s a subject which has fascinated society for millennia and it doesn’t look like that is going to stop any time soon. I’m sure most of us have had a dream which we are convinced has some greater significance: a dream about facing our fears or that person who you hadn’t thought about for years.

In the distant past, dreams were associated with divine will and prophetic qualities. Ancient Egyptian and Greek scholars produced dream manuals which were used to interpret nightly visions. Flash forward to the 19th and early 20th century and there was a shift towards understanding dreams in terms of their psychological causes and consequences. It was not until 1953 with the discovery of rapid eye movement (REM) sleep that the objective study of dreaming was possible.

Since then, we have come to appreciate that not all dreams are not created equal. Depending on which stage of sleep the dream is recalled from will depend on the type of dream. Firstly, dreaming does not only occur during rapid eye movement (REM) sleep but can occur at any stage during the sleep cycle. Dreams at sleep onset and during short naps appear to be relatively faithful, if not stripped back, representations of daily activities. By contrast, dreams reported during REM sleep and after longer periods of sleep appear more bizarre and less clearly linked to daytime activities.

So why do we dream? What attempts have there been to try to understand these nightly visions of the surreal?

Wish Fulfilment

Freud stated in ‘The Interpretation of Dreams’ that all dreams were wish fulfilment of our uninhibited desire. The dream provided an outlet for these desires and prevented them seeping into wakefulness. The dream (manifest) content could thus be interpreted and inform the analyst about the unconscious desires of an individual. The latent, or unremembered and unconscious, dream content could be reached through employing dream analysis and psychoanalytic techniques. Although you can still buy manuals which claim to teach you how to analyse dreams in line with early psychoanalytical thought, the validity of these are questionable at best. The steps required to reach the ‘latent content’ can be idiomatic and despite claims that an airplane can represent unconscious desires sometimes “…a cigar is just a cigar”.

Dreaming to Remember

It has been shown that dreaming is linked to the activities which we complete during the day. This should come with little surprise to most. We can often pinpoint our dreams back to activities we have completed during the day – even if they appear in bizarre contexts.

Robert Stickgold at the Department of Psychiatry, University of Harvard, showed this with a simple experiment. Participants were required to play Tetris at fixed periods and to sleep in a monitored laboratory setting. During this time, participants were asked about their thoughts and dreams in the first hour of attempted sleep.  He found that by asking participants to play Tetris for extended period of time that a significant number of sleep-onset dreams and images were found to be linked to Tetris (i.e. images of the blocks falling into place and lines of blocks disappearing when complete).

tetris

A study from the same group led by Erin Wamsley at the University of Harvard built on this by exploring whether the presence of task-relevant dreams was associated with performance. They asked participants to complete a virtual navigation task whereby they had to reach a goal (e.g. a tree). Participants were then re-tested just over 4 hours after the initial completion of this task.

Half of the group were then provided with an opportunity to nap and the other half remained awake. Unsurprisingly, from what we already know, the nap group were found to show a greater improvement on the task at re-test. Interestingly, and importantly for dreaming, the participants who dreamed about the maze during the nap also reported the greatest re-test improvement. Okay, perhaps this might simply have been due to the fact that these participants were simply thinking of the task more? However, this doesn’t appear to be the case. The wake participants were also asked about their task-relevant thoughts but the researchers found no benefit to re-test performance here.

Collectively, these studies suggest that dreaming may be a result of the brain consolidating and organising new memories alongside existing ones. However, they don’t tell us that dreaming is responsible for our improvement but that dreaming may be a marker of it.

Activation Synthesis Theory (and Dreaming to Forget)

Other theories suggest that dreaming has little relevance to memory or other functions. The Activation Synthesis theory proposed by Allan Hobson and Robert McCarley in 1977 claims that dreaming is the product of seemingly random or automatic brain activity produced during REM sleep.

These ‘random’ activations have their origin in the brain stem and are transmitted to the forebrain during REM sleep. The cortex then compares this activation against previous memories to make sense of the neural activity produced by the brain stem. It is claimed that a similar mechanism may explain non-sleep hallucinations and dreaming. This theory forms the basis for another hypothesis for why we dream: not to remember but to forget. This should seem counter-intuitive based on what we know about sleep and memory – and all that advice you’re given by teachers or colleagues before an important exam or meeting.

However, Francis Crick (yes, that Francis Crick) and Graeme Mitchison argued in 1983 that sleep has an important role in identifying faulty connections within the brain – an inevitable problem facing a neural network of sufficient complexity. These ‘faults’ arise during development and as a part of the multitudinous memories and connections we develop throughout any ordinary day. During REM sleep, these ‘faults’ are dampened down and their connections weakened. This ensures the brain works efficiently.

So, where does dreaming fit in?

Quite simply the ‘faults’ in the brain are experienced as dreams. Our dreams are the connections which our brains’ are trying to suppress during REM sleep. The overall purpose of such a mechanism is to ensure the efficient functioning of a brain with finite processing power.

However, if our dreams are the memories we are trying to erase, in one form or another, why do we have recurrent dreams? Crick claims that this is tricky for the theory but may be as a result of the threatening nature of recurrent dreams. The anxiety and fear associated with such dreams is likely to wake up the dreamer and to subsequently be remembered. This may interfere with the reverse learning process.

Primitive instinct rehearsal theory of dreaming

Another appealing theory is that dreaming is not a product of vital or random brain activity but rather that it serves an evolutionary advantage. More specifically, it has been claimed that dreams may help us deal with threatening situations in our daily lives by giving us an opportunity to practise overcoming them. In turn this increases our survival odds and also increases the chance we will successfully reproduce – passing on that ability to dream to our offspring.

Anecdotally this might explain why anxiety and fearful dreams are commonly reported by many different people, and why they share a common theme. However, like Freud, this theory assumes that dream content must have a distinct purpose. It’s hard to falsify such a theory and provide evidence which would conclusively disprove its existence as many dreams could conceivably be interpreted in a practise or threat-related manner.

Dreaming and Creativity

Finally, it’s an old claim that creativity and dreaming are linked together. Authors such as Mary Shelley and Steven King relate their tales of horror back to dreams they’ve remembered. Salvador Dali enjoyed the phantasmagorical images produced through his dreams and used them as inspiration for his surrealist art.

What does the science say about creativity and dreaming?

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Surveys of students’ ability to remember and recall dreams correlates with openness to new experiences, fantasy proneness, and may even be associated with a lesser ability to filter out environmental input. Cumulatively, this suggests that traits associated with creativity and ‘thinking outside the box’ are associated with an ability to recall dreams. However, this does not mean that we dream in order to improve creativity but that creativity is likely a product of bizarre, frightening and fantastical dreams. We benefit from dreaming but only insomuch as an incidental source of inspiration.

Overall, even though the content of your dreams may not necessarily provide a convenient road to your hidden thoughts and desires, they can provide us some fascinating insights into the sleeping brain. Despite frustrated responses from others, that remains my response when they ask about last night’s dream about planes, trains and giant chickens.

Don’t ask.

Inquisitive Tortoise

References:

Crick, F., & Mitchison, G. (1983). The function of dream sleep. Nature, 304(5922), 111-114.

Stickgold, R., Malia, A., Maguire, D., Roddenberry, D., & O’Connor, M. (2000). Replaying the game: hypnagogic images in normals and amnesics. Science, 290(5490), 350-353.

Wamsley, E. J., & Stickgold, R. (2010). Dreaming and offline memory processing. Current Biology, 20(23), R1010-R1013.

Wamsley, E. J., Perry, K., Djonlagic, I., Reaven, L. B., & Stickgold, R. (2010). Cognitive replay of visuomotor learning at sleep onset: temporal dynamics and relationship to task performance. Sleep, 33(1), 59-68.

Image Credits:

Dream Catcher (Header)

Tetris (Body Text)

Nightmare (Body Text)

 

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Filed under Dreaming, Literature, Psychology, Sleep Science