Training in the sleep camp
4 ways how dreaming at night helps us during the day
Text: Anna Gielas
Illustration: Till Hafenbrak
Sometimes they are nice, sometimes scary, and sometimes embarrassing. The dreams that we have while we sleep have been baffling scientists for a long time. For example, scientists still don’t have a conclusive answer to the question why images during our sleep exist at all. However, as dreams seem to have been part of human life since our evolutionary origins, scientists have attributed fundamental functions to them. And Susan Llewellyn, Professor Emerita from the University of Manchester is no exception. In her latest book What do Dreams do? she examines dream images and describes their assumed functions and how they have been impacting the daily life of humans in the past and now.
“Originally, we dreamt to survive”, the scientist writes and refers, among other things, to the socalled threat simulation theory. According to this hypothesis, dreams are a training field for
various threat scenarios – and for practising right (and wrong) reactions to these scenarios. For example, when the sleeping person
dreams of a life-threatening situation where they should flee but
cannot move an inch. This nightmare emphasizes how important a timely flight is and this warning in the night made survival easier for our ancestor – or so the theory goes. Dreaming is thought to have
prepared early humans for their dangerous environment in other
ways, too: “It served as a training field to recognise patterns that could
be important for survival”, Llewellyn says. The human brain is designed to recognise patterns and regularities in the surroundings. For example the fact that dark clouds are a sign for an imminent storm. This enables humans to predict and prepare for future events in a seemingly chaotic environment. According to Llewellyn, dream
scenarios might have helped early humans to recognise causal links
and regularities better and faster while they were awake. As is well known, we have been living as Homo sapiens in a mostly self-created
environment for some time and the differences to the world that surrounded our ancestors are considerable. In our cities there are no predators anymore and the weather forecast is delivered to us by
the weather report. Yet even in the civilised world, dreaming has not lost its meaning, according to Llewellyn: “Today, many dreams seem to
serve the avoidance of sociocultural mistakes that could lead to us being expelled from society, for example.” Such an expulsion from the community has always been a threatening scenario for humans. This might be why we often dream of embarrassing situations – it allows us to avoid them more efficiently when we are awake.
While we sleep, our memory of what we have recently learnt is strengthened.
This is known as “memory consolidation”. Networks of nerve cells in the brain are activated in a certain order and – if this happens repeatedly –
connected to each other permanently. These connection constellations correspond to a certain memory.
Scientists have found evidence that recently learnt contents are consolidated while we sleep – especially during the dreamless deep sleep phase.
However, dreaming could also function as a specific memory aid, Sue Llewellyn suggests. She can see parallels between dream images and the complex mnemonics that mnemonists use when they are awake. “The tricks and techniques used by mnemonists are primarily based on visualisation – significantly less on other senses”, she writes. Fanciful images
are crucial for mnemonists – and the dreams of most people are similarly fancy, Llewellyn explains.
The popular advice to “sleep on it” might be about more than just time for consideration: Dreams seem to enhance the decision process. At least this is what some studies suggest. They show, among other things, that the brain has better access to early memories while we dream than when we are awake.
“What’s more, the brain establishes complex associations between the individual experiences and the knowledge of the sleeping person during the REM phase in which most dreams take place”, Llewellyn writes. With this unconscious combination process, dreams might help us in making decisions, she speculates. “After all, 95 percent of our thought processes are performed subconsciously.”
Being creative includes, among other things, the ability to interpret something
in a new way by breaking it down into its elements and subsequently reassembling these in an unexpected way. “This definition of creativity resembles the dream processes”, Llewellyn writes.
Here, our past experiences and knowledge is dissembled and put together again. These associative processes seem to promote creativity.
This was demonstrated by a team of researchers at the Harvard Medical School, for example: When the participants of the study were woken from the dream sleep phase and asked to complete an associative task, they had more fanciful associations than normal. For example, one sleepy participant came up with “altar” when given the cue “table” compared to
“chair” which was their more awake and more focused answer. The participants that had just been woken up also found it easier to make less obvious connections, such as associating the words “sink”, “dust” and “actor” with the keyword “star”. “Creative people often report that they have associative insights and new ideas when they are in an unfocused, relaxed or even dreamy state of being awake”, Llewellyn writes. Hence, we might be most creative when we are sleepy – be it in the middle of the night or in broad daylight.