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Why can't we remember dreams? The neuroscience of ecstasy and sadness

It seems like a pact with the devil. As soon as you're in a position to record a dream, it starts to disappear

Douwe Draaisma
May 4, 2015 12:00AM (UTC)

Excerpted from "Forgetting: Myths, Perils and Compensations"

There’s no time to lose, I heard her say Catch your dreams before they slip away.

When we sleep, wrote English psychiatrist Havelock Ellis over a hundred years ago, we enter a ‘dim and ancient house of shadow’. We wander through its rooms, climb staircases, linger on a landing. Towards morning we leave the house again. In the doorway we look over our shoulders briefly and with the morning light flooding in we can still catch a glimpse of the rooms where we spent the night. Then the door closes behind us and a few hours later even those fragmentary memories we had when we woke have been wiped away.


That is how it feels. You wake up and still have access to bits of the dream. But as you try to bring the dream more clearly to mind, you notice that even those few fragments are already starting to fade. Sometimes there is even less. On waking you are unable to shake off the impression that you have been dreaming; the mood of the dream is still there, but you no longer know what it was about. Sometimes you are unable to remember anything at all in the morning, not a dream, not a feeling, but later in the day you experience something that causes a fragment of the apparently forgotten dream to pop into your mind. No matter what we may see as we look back through the doorway, most of our dreams slip away and the obvious question is: why? Why is it so hard to hold on to dreams? Why do we have such a poor memory for them?

In 1893, American psychologist Mary Calkins published her ‘Statistics of Dreams’, a numerical analysis of what she and her husband dreamed about over a period of roughly six weeks. They both kept candles, matches, pencil and paper in readiness on the bedside table. But dreams are so fleeting, Calkins wrote, that even reaching out for matches was enough to make them disappear. Still with an arm outstretched, she was forced to conclude that the dream had gone. She would sink back ‘with the tantalizing consciousness of having lived through an interesting dream-experience of which one has not the faintest memory.’ Even the most vivid of dreams dissolved into thin air:

To delay until morning the record of a dream, so vivid that one feels sure of remembering it, is usually a fatal error. During the progress of the observations, the account of one dream, apparently of peculiar significance, was written out in the dark by the experimenter, who then sank off to sleep with the peaceful consciousness of a scientific duty well done. In the morning the discovery was made that an unsharpened pencil had been used, and the experimenter was left with a blank sheet of paper and no remotest memory of the dream, so carefully recalled after dreaming it.

That arm reaching for the matches and falling back says it all.


A few preliminary remarks. Research into dreams is a methodological nightmare, if you will forgive the irresistible metaphor. One of the problems is that the results of research into dreams vary according to the methods used. In the time when rapid eye movements were taken to be evidence of dreaming, it seemed you might as well carry out experiments using animals, as long as they exhibited rapid eye movement (REM) sleep. A series of experiments was done to test the theory that preventing an animal from dreaming would eventually have a deleterious effect on its memory. The chosen laboratory animals, rats, were placed on floating platforms. During deep sleep they lay motionless and all was well, but during REM sleep they became slightly restless and would slide off into cold water. Splash: wide awake. After a few nights without REM sleep they did indeed forget a learned task, a route through a maze, more quickly. Another experiment was designed to test the same hypothesis about REM sleep and memory, again with rats but using a different procedure. As soon as rapid eye movements occurred, the rats were carefully woken by being shaken, rather in the way that a child will wake its guinea pig. These rats had no problem at all with learning their maze task. It seemed the learning difficulties had arisen not because of the deprivation of REM sleep but as a result of the stress caused by sliding into cold water. The conditions of the experiment determined the conclusions about dreams and memory to be drawn from it.

A second complication is that we have no direct access to another person’s dreams. Personal access to our own dreams itself presents all kinds of unavoidable obstacles. All we can measure about dreams is the behavior of the dreamer, such as the eye movements made while dreaming, which provide only indirect data, as we shall see. The researcher is dependent on the dreamer’s own report and no one understands better than the dreamer that the report does not correspond precisely with the dream. Dream research is the domain of oblique measurement, derivative knowledge and hunches. We should not expect any absolute conclusions or definitive answers here. The dream researcher, just like the dreamer, explores dimly lit rooms.

Then there is the incoherence of many theories on the subject. In psychology you are almost guaranteed to encounter the most diverse and sometimes contradictory theories about one and the same phenomenon. Insights change, interests shift, some questions lose the background from which they derived their significance, but even in psychology it is rare to find such a wide range of theories as there are concerning dreams. This applies to the details, but it is no less true of some of the most general insights and attitudes. We come upon the belief that dreams provide a profound understanding unachievable by any other means right alongside a conviction that they mean nothing at all. Some psychologists are convinced dreams are absolutely essential to good mental health, others that nothing will change if a person no longer dreams, perhaps as a result of certain medication. Dreams are utterly indispensable, or a chance by-product, or anything in between. Reading about dreams and memory, I often had the feeling that I too was wandering through a dim and ancient house of shadow.


The lizard dream

The most obvious explanations as to why we forget dreams were put forward in 1874 by German philosopher Ludwig Strümpell. He suggested that dream images are too weak to penetrate the memory, just as in daytime many stimuli are too weak to leave any trace. Dream images are rarely experienced more than once, so repetition, which is generally a powerful strategy for remembering things, does not occur. It is perhaps no accident that those dreams we do remember tend to be recurring dreams. Most people simply care too little about their dreams; as soon as they wake, the tasks of the day demand their full attention and all memories of the dream evaporate. Strümpell observed that people who kept a dream diary for a while found that they dreamed more and became better at remembering their dreams, a phenomenon that has since been corroborated repeatedly. Lastly, dream images were thought too incoherent to be recorded with the help of orderly associations. They consist of unconnected images and our memories are better at dealing with a series of events that follow each other in a natural order. To use a metaphor that was not available in Strümpell’s day, dreams are like a chaotically edited film, with fragmentary scenes, so it is hardly surprising that we fail to remember the images. To Strümpell the puzzle is not so much why we forget dreams as why we occasionally remember them.


Strümpell’s explanations are old, but that does not mean they are outdated. Many modern researchers point to a lack of associative cohesion in dreams, or to poor concentration in the transitional phase between sleeping and waking. It is hard to test the validity of the argument that in a dream all kinds of things happen that are inexplicable, illogical or downright impossible and that lack of cohesion makes them hard to recall. We might just as easily arrive at the opposite conclusion. If in real life I suddenly found myself in the basement with the attractive lady next door, I would certainly remember it a week later, all the more so because our house has no basement. I know I have had dreams of that kind from time to time, but I cannot remember a single one of them. Even the sometimes decidedly peculiar content of our dreams is no guarantee that we will file them away. Moreover, the realization that there is something odd about the events of a dream usually comes later, when you relate or contemplate the dream. You then spot one incongruity after another: people who could never have met, dead people brought back to life, people who turn up out of nowhere and with whom you start chatting without first asking where they have suddenly sprung from. In dreams you may be able to speak fluent Spanish, or you meet someone in Berlin even though you were at home a moment ago. When dreaming, nothing surprises us. So how the strange nature of many dreams affects our ability to remember them remains an open question.

What makes the forgetting of dreams so puzzling is that there seem to be so many intimate connections between dream and memory. Take ‘day residues’, those fragments of the day’s events that return to us at night in our dreams. They surely suggest that dreams derive some of their material from our memories. There are even examples of dreams that seem to prove the dreamer has access to more memories than in waking life. This is an example of the phenomenon known as hypermnesia. It is as if the dreamer’s memory holds open doors that remain closed in daytime. Freud – there he is already – writes in The Interpretation of Dreams about the experience of Belgian philosopher and psychologist Joseph Delboeuf.

Delboeuf dreams he is walking across his snow-covered land when he finds two half-frozen lizards. He picks them up, warms them and puts them in a cleft in the wall. He plucks a few fronds from a fern and holds them out to the lizards. In his dream he knows the name of the fern: asplenium ruta muralis. A little later he spots another two lizards coming to eat the fronds and when he looks round he sees a whole throng of them, so many that they cover the path, all on their way to the cleft in the wall.


Delboeuf knew hardly anything about plants, but he was curious about the name he had dreamed and to his amazement it turned out to exist in reality: asplenium ruta muraria. In his dream he had merely bastardized muraria into muralis. It was a mystery to him how the name of a plant he had never heard of before could pop up in his dream.

Sixteen years later, while visiting a friend, he happened to look through a herbarium. There he recognized the fern frond from his dream. The Latin name was written beneath it, in his own handwriting. Only then did he recall that the friend’s sister had visited him in 1860 with that very herbarium, intended as a present for her brother, and that he had offered to write in it the Latin name of each plant, with the help of a botanist. Two years before his dream, he had written it out in full: asplenium ruta muraria.

That is not the end of the story. One day, when he was looking through old copies of an illustrated newspaper to which he had a subscription, he suddenly saw the procession of lizards from his dream, on a cover dated 1861. So it was only after 18 years that Delboeuf was able to reconstruct the correct chronology: in 1860 he noted the Latin name in a friend’s herbarium, in 1861 he saw the cover featuring the march of the lizards, in 1862 he had his lizard dream, in 1877 he saw the depiction of the march of the lizards for the second time and in 1878 he looked at the herbarium again.


Delboeuf published his account in 1885, in a monograph about dreams, recalling his dream of 1862. The striking thing is that the dream included elements that at the time were in the fairly recent past, only two years or so back. Furthermore, the dictated Latin name was actually written out by him, an example of what would now be called ‘dual coding’, a trace both aural and visual, which meant he ought to have been able to remember it all the more easily, yet he could recall neither the name nor writing it down. The dream, by contrast, a thing usually so fleeting, was still in his memory 16 years later when he saw the herbarium. If all this happened precisely as he said it did, then it is a typical example of hypermnesia, when the dreamer remembers something that is not accessible to his waking consciousness. Delboeuf, incidentally, died in 1896, four years before the publication of The Interpretation of Dreams, so he never read Freud’s explanation of his dream as an unconscious protest against castration. Lizards that lose their tails are able to grow them back.

Freud and other dream researchers collected many examples of hypermnesia in dreams. In his waking hours, Havelock Ellis tried in vain to come up with the name of an unpleasant Chinese scent. It suddenly came to him while he slept: ‘patchouli’. When he woke in the morning the name had gone again. One of Freud’s patients described during analysis a dream in which he ordered a glass of ‘Kontuszówka’ in a coffee house, adding that he had never heard of the drink. Impossible, said Freud, it’s a Polish brandy and they’ve been advertising it in this city on posters for quite some time. The man refused to believe him, until a few days later he saw just such a poster at a street corner he had walked past at least twice a day for months. Freud himself was mystified by the dreamed image of a church tower he could not place – until some 10 years later, when he spotted it from the window of a train and realized he must have seen it on a previous journey along the same route. In our waking consciousness, Havelock Ellis wrote, our associations are focused, concentrated; in our dreams they are diffuse, more wide-ranging, but we lose the power to steer them: ‘Our eyes close, our muscles grow slack, the reins fall from our hands, but it sometimes happens that the horse knows the road home even better than we know it ourselves’.

Hypermnesic dreams are sometimes regarded as proof of the theory that nothing of what we experience ever disappears from the memory. A brief glimpse of a drawing, a Latin name in a long list, a poster, an absent glance from a train window – it is all still there; the neurological traces of these experiences are laid down for the rest of our lives, even if they are activated again only by chance.

For some of Delboeuf’s contemporaries, that same hypermnesia explained a puzzle no less fleeting: the déjà-vu experience. All experiences, including dreams, even the dreams we do not remember the following day, are stored away in our brains. If we experience something in daytime that has enough associations in common with what we have dreamed, we will feel we have experienced it before. In a sense we have, since beneath our experience in the present lies the shadowy image of the dream that resembles it. Because we cannot date the dream and the associations are vague, it seems like an event of long ago, as if part of an earlier life.


Whether our memories really do contain everything we have ever experienced is impossible to know in any absolute sense. Whether in our dreams we have access to a larger, deeper, richer or even completely different collection of memories than in daytime is no less hard to determine, since that would involve comparing examples like those of Delboeuf, Havelock Ellis and Freud with what remains inaccessible in a dream yet can be remembered when we are awake. Such bookkeeping is impossible to perform. It is undoubtedly the case that in dreams things can pop up that lie off to one side of the day-to-day paths of association. Havelock Ellis’s explanation is hard to fault. During a dream some associations fall away and stories lose coherence as a result, but new connections may arise, which in turn lead to places in the memory containing material that has not risen into consciousness for so long that it seems forgotten. To quote Havelock Ellis’s own cryptic recapitulation: ‘We remember what we have forgotten because we forget what we remembered’. Emigrants of a certain age who have been speaking a second language for 50 or 60 years may to their own surprise start dreaming in their mother tongue again. The dream seems to provide access to a vocabulary that the associations of daytime never touch upon.

Sometimes dreamers have the feeling of hearing or seeing something that is so perfect and so far outside normal experience that they would like nothing better than to lay down the experience in their memory immediately and forever. In 1766, the French astronomer Jérôme Lalande made a trip through Italy that took him to Padua, the university city of the Veneto region. There he decided to visit Giuseppe Tartini, a composer, music theorist and, for the past year, since injuring his hand in a fencing duel, retired virtuoso violinist. Tartini, then 74 years old, told Lalande the story of the ‘Sonata del Diavolo’. At the age of 22, he had dreamed one night that he had made a pact with the devil for his soul, and that he had given his violin to the devil to see whether he could play something beautiful. Lalande’s account goes on:

How great was his surprise when he heard him play a sonata so extraordinarily beautiful and so exquisitely performed that it surpassed everything he had heard up until then. He felt ecstatic, enchanted, he was carried away, his breath caught in his throat and these great emotional shocks woke him up. He immediately reached for his violin in the hope of capturing some of the sounds he had just heard. In vain. The piece he wrote then is the most superb he ever composed and he actually called it the Devil’s Sonata, but it compared so poorly with what he heard in his dream that he would have been willing to smash his violin and give up music forever if only he could have secured the means of capturing the piece he had heard.

There is no reason at all to assume that Tartini invented the dream, if anything quite the opposite, since he was known as a reserved, self- effacing man. He had never previously revealed anything about the inspi- ration for his music. The mottos he attached to his compositions were written in a code that was not deciphered until 1932; they turned out to be derived in part from the work of Petrarch. The essence of what he experienced that night may well be true exactly as he describes it: you hear something of unearthly beauty in a dream and realise on waking that you cannot recapture it. Many of us will have had personal experience of this, if not with music then with a voice, a poem, a landscape, a painting. Or you may dream of a bodily sensation such as floating or flying that, once awake, you can no longer reproduce in its dreamed intensity. After a while, what you recall of the dream is no longer the music, the landscape, the floating, but the ecstasy you felt during the dream. It truly seems like a pact with the devil. As soon as you are in a position to record the dream, whether in your memory or on paper, it starts to disappear.

Everyone has at some point reached for a violin, as it were, after a remarkable dream and for no one has the result been any different than it was for Tartini. What we manage to conjure up as we write or talk about a dream is but a poor reflection. No matter how convincing the account may seem to the listener, the person recalling the dream is only too well aware of the inadequacy of the version conveyed. Of course even if we are fully awake when listening to music that transports us, it is not easy to remember or reproduce it accurately. Even in a waking state we often write down entire stories using a pencil that turns out not to have been sharpened. So really the question is: why does the memory have so much more difficulty with dreams than with things we experience in a waking state? We do not need to explain why we forget, but rather why dreams are particularly easy to forget.


Excerpted from "Forgetting: Myths, Perils and Compensations" by Douwe Draaisma. Published by Yale University Press. Copyright 2014 by Douwe Draaisma. Reprinted with permission of the publisher. All rights reserved.

Douwe Draaisma

Douwe Draaisma is professor of the history of psychology at the University of Groningen and author of several best-selling books on topics relating to memory. He lives in Groningen, Netherlands.

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