The Neuroscience of: Dreams
Why do we dream? Shail Bhatt investigates the phenomenon that we all experience.
“They say dreaming is dead, no one does it anymore. It’s not dead it’s just that it’s been forgotten, removed from our language. Nobody teaches it so nobody knows it exists. The dreamer is banished to obscurity. Well, I’m trying to change all that, and I hope you are too. By dreaming, every day. Dreaming with our hands and dreaming with our minds. Our planet is facing the greatest problems it’s ever faced, ever. So whatever you do, don’t be bored, this is absolutely the most exciting time we could have possibly hoped to be alive.” – Waking Life (2001)
Apart from the fantastic fantasies and endless realms of vivid imagery that they provide, do dreams actually serve a greater purpose? What is the reason for dreams that imagine the embarrassment of not being able to finish an exam on time? Why, in some dreams, do our teeth fall out, or we try to fly but cannot? Dreams are the images, thoughts, feelings and sensations that run through our brain while we are sound asleep. Subsequently, these mental experiences are interpreted by the brain and evolve into a story.
The reason for their existence is still not fully understood, and there are many conflicting theories. Some say that dreams serve an evolutionary purpose and that we run simulations of possible scenarios so that we are prepared for them if they occur. Others say that dreams are purely random and occur because various neurons fire in a haphazard order and evoke different images and emotions.
However, the reality might be a compromise between both, given that some aspects of the brain continue to function in the same organised structure as that applied when awake. For example, thought and dream processing follow virtually identical mechanisms. Just like they do whilst we’re awake, our brains also capture sensory information from our surroundings and try to make sense of them in a process called ‘dream incorporation’. For example, your alarm ringing might be perceived in your dream as a loud explosion.
Most often, dreams occur during Rapid-Eye-Movement (REM) sleep, a phase where the brain works at a capacity similar to that of waking life, which is characterised by the distinct fluttering and moving of the eyes. REM sleep cycles occur approximately every 90 minutes, and also play a role in encoding and preserving our memories by maintaining neural pathways.
Specifically, REM sleep originates from the base of the brain, at an area called the pons, from which signals travel to the thalamus, and then to the cortex. This pathway is associated with learning, thinking and the processing of information. Because memories and thoughts are generated from the systematic firing of particular neurons, dreams are thought to include aspects from our memory in order to further solidify them. Nightmares however, occur primarily due to high activation of the amygdala, another component of the brain responsible for fear and anger.
An analysis of the motifs that occur during dreams revealed that there are 15 main themes that dreams revolve around. These themes are classified into three categories: Ego Ideal (where the dreamer falls short of social expectations), Grandiosity (where the dreamer has a superior status or superpowers) and Persecution (where the dreamer encounters something evil). Motifs themselves include failing or performing badly in front of others, punishment, being physically attacked, having magical powers like flight, or meeting a celebrity. Therefore, there are repetitive ideas which we experience while dreaming, many of which are metaphorical for events in our day-to-day lives.
Studies have revealed that dreams enhance creativity, and hormones are at the heart of this. During REM sleep, cortisol, a stress hormone that regulates many things including blood glucose levels, fat breakdown and the immune system, is released. Although cortisol distorts memories and reduces memory recall, the brain instead tries to make sense of things and find patterns, and piece together these distorted memories and thoughts, paving the way for a unique form of innovative and creative thinking. Levels of dopamine, a hormone which controls motivation and pleasure, are also increased. Elevated levels of dopamine in turn create a positive feedback loop, which not only encourages dreaming, but stimulates the thought process when undertaking creative activities.
In conclusion, dreams are much more than just a chaotic scene of abstract and bizarre images. Dreams can be useful, and they can help us retain information, ideas and memories. Ultimately though, dreams are a gateway to a place where the most unbelievable things can happen!