The Biology of Dreaming
A dozen of us were floating around on the lake, throwing paper airplanes at each other from our perch. Paddling our couches back to the cabin, we jumped onto the deck and piled into the house. Before long, our potato chips were soggy and everyone else was fast asleep in a pile on the floor, when the largest wave I had ever seen came crashing over us…
And suddenly I was jerked awake in my bed, safe and not soaking wet. There are many people who would dissect this dream and guess at what it might symbolize, but perhaps a better question would be: why is my mind being filled with this bizarre story that doesn’t make any sense?
What is dreaming?
Traditionally, dreaming had been identified as an activity that occurred during rapid eye-movement (REM) sleep. Many more recent studies, however, have shown that dreaming is just as common during non-REM sleep phases. Our whole brain is active during sleep and dreaming, similar to when we are awake. This study showed that there were “hot zones” of high-frequency activity in regions associated with conscious experiences during dreaming, and that the same parts of the brain in charge of certain actions when awake correlated with brain activity during similar actions when dreaming. For example, dreams containing speech triggered activity in the language area of the brain. This means that, as weird as dreams can be, to our brains they are incredibly similar to consciousness.
If you’re someone who often remembers their dreams, you’ve probably noticed that dreams commonly contain traces of memories: something you did during the week, people and places you’ve known, something that’s been on your mind, etc. Memories do seem to incorporate into dreams in very specific ways, however. Episodic memory (memories about discrete events) are very rarely present in dreaming, whereas autobiographical memory (long-lasting memories about life experiences) show up in over 80% of dreams. So, you probably won’t dream about the memory of your first day of college, however your favourite college professor might be present in a dream taking place in your college girlfriend’s apartment.
So, why do we dream?
Some of the oldest and most prevalent dream theories are the psychoanalytic theory of dreams, the activation-synthesis model of dreaming, and information-processing theories. The psychoanalytic theory is a subdivision of Sigmund Freud’s theories. This theory forms the basis of dream interpretation, and attempts to explain the meaning of the thoughts and emotions processed during sleep. The activation-synthesis model theorizes that dreams are created by changes in neuron activity that activates the brain stem during REM sleep. Lastly, information-processing theories base their hypotheses on the impact that sleep has on memory retention; They suggest that dreaming may be a by-product of this. Ultimately, these theories only really give us reasons that dreaming occurs (or what they mean when they do occur), rather than a purpose for it.
Okay, so is there a purpose to dreaming?
We don’t actually know the answer to this question. Similar to the reasons why we dream, there are many theories that have been tested, but no super consistent results. It is commonly theorized that dreaming is not only a bi-product of memory retention during sleep, but a mechanism used to actually perform this retention. A slightly more interesting theory is that dreams can be used as threat simulations, utilizing a defense mechanism that essentially trains us to be better at threat detection and avoidance. Another theory is that dreaming provides a safe space for our brains to explore overwhelming and highly complex situations that would cause unwanted mental states during consciousness, serving a need for psychological balance.
Our brains are complex and difficult to study, and the results from these studies have shown merit to a variety of different theories behind the how, what, and why when it comes to dreaming. Nearly everyone has experienced dreaming, and it is thought that even if you don’t remember your dreams, everyone does dream multiple times a night. This makes it pretty safe to say that there must be a reason behind the phenomenon; whether it be a bi-product of some important function that occurs while we sleep, or if it has its own purpose. As we continue through this series, we will investigate further into various dreaming phenomena and how they integrate into these different theories, so be sure to subscribe to our blog or follow us on social media so you don’t miss it!
