Like the famously abstract pop singer Billie Eilish asked in one of her songs, “When we all fall asleep, where do we go?”

I'm sure many of us have wondered why we dream. There is ambiguity among researchers about the purpose of dreams, but they are generally known to aid our emotional, mental, and physical health, and they have social and cultural meaning as well. As someone who knew next to nothing about this topic, I always felt my dreams were a surreal amalgamation of the main things I experienced in the day. While my friends and I occasionally mused about the purpose and causes of them, I never dug deeper into the scientific details. Those rare conversations often just dissolved into fits of laughter over animated retellings of our most eccentric dreams. Now that I have had the opportunity to delve into the specifics of dreaming, the biology student in me marvels at the psychologically enigmatic nature of our brain activity once we go to sleep. And although the complexity of dreams may forever remain one of life’s unsolved mysteries, it stands to remind us of the fascinating capabilities of our subconscious.

That’s not to say that we know nothing — science has, over the years, brought quite a lot about dreaming to light. People have different kinds of dreams based on the stage of sleep they are in. Scientifically speaking, one can dream at any point in the sleep cycle, but the most vivid dreams occur in the rapid eye movement (REM) stage, when the brain is most active. The REM cycle, which happens more and more often as the night goes on, consists of high levels of eye motion and can cause us to have odd, specific dreams. Usually there is little muscle activity and voluntary muscles are paralyzed during the REM cycle, proving that it is the deepest stage of sleep. Since the frontal lobe is inactive during dreams, they are devoid of logic or reasoning and can manifest in the most bizarre ways. Furthermore, emotion in dreams is triggered by the limbic system, of which the amygdala is the most responsible for strong and often negative feelings. The three other stages of sleep are non-REM, one that follows sleep onset and elicits dreams of falling, and the other two that trigger short dreams related to recent events. These range from early in the night to throughout the duration of sleep, with low eye and muscle activity. As most things do, dream frequency and content vary from person to person. They are affected by factors such as strength of memory, age, and how one is woken up. Older people are less likely to remember things after waking up, and being interrupted in the middle of sleep by an alarm or person, rather than waking up naturally, leaves the dream fresh in one’s mind. The linkage of memory to dreams has been studied, concluding that dreaming aids in permanently storing memories.

Strangely enough, we are sometimes conscious of our dreams in a state called lucid dreaming, which stems from an increase in activity in parts of the brain that are usually restful during sleep. These dreams exist in a liminal space between sleeping and waking, and can be modified and engineered by the dreamer. From the perspective of a frequent lucid dreamer, I can say that the plot of my dreams isn’t always created by me, but I often can maneuver them in the direction that I want. Something that I still can’t fully get used to is that often, when I am awoken from a lucid dream, it does not feel like I have slept at all, rather that the dream was just another part of my active, waking life. That’s what it feels like to be in a lucid dream, one where the dreamer takes charge — much like the agency you have over your body when you’re conscious — rather than letting their subconscious control them. Studies have indicated that this occurs in people with a bigger prefrontal cortex, the part of the brain that controls decision making and memories. These people are usually overthinkers, or very self-reflective, and hence are most likely to create their own storyline in dreams. Moreover, lucid dreaming can be therapeutic, increase fine motor skills and creativity, and also promote better problem-solving skills. However, it can also have a negative impact on quality of sleep, and could be harmful for those with mental health disorders by causing delirium or hallucinations.

One may think that, due to low muscle activity during sleep, these events can only take place inside our heads. However, humans move around in their sleep as well, some on a slightly more advanced level than just tossing and turning during nightmares. Sleepwalking, also known as parasomnia and formerly known as somnambulism, is a relatively common affliction that manifests largely in children. While I never had a personal experience with it, I did read author Enid Blyton’s Malory Towers and St Clare’s books growing up, so I always had a rather comical view of sleepwalking. The description of sleepwalkers in the books was spooky — glassy eyes and a zombie-like gait — but the light-hearted and comedic portrayal of them was what stuck. However, sleepwalking can actually be injurious to one’s mental and physical health, as well as to that of people around sleepwalkers during an episode. Handling sharp objects, trying to drive a vehicle, and exhibiting violent behavior can be life-threatening, while urinating in inappropriate places or having aggressive outbursts leads to embarrassment. This could cause trauma to partners, roommates, and family members, or even go as far as to hurt them. There are numerous factors that cause sleepwalking, including genetics, sleep deprivation, brain injury, stress, and others. Although preventative measures for some of these are obvious, others may require a visit to the doctor or behavioral therapist. Methods to minimize harm done by and to sleepwalkers include locking doors and windows, removing tripping hazards from the floor, and keeping sharp objects hidden or out of reach.

But why should we have all the limelight? In this anthropocentric world, it may be common to think that humans are the only species advanced and complex enough to dream, but animals experience the phenomenon as well. Scientists at MIT “recorded the activity of neurons in a part of the rat brain called the hippocampus, a structure known to be involved in the formation and encoding of memories.” Through this study they found a resemblance between the pattern of the way the rats’ neurons fired while they were running in mazes and in their dreams. Biologists from the University of Chicago discovered something similar in a species of bird called zebra finches, who learn and develop their ability to carry a tune. The research depicted that their brain activity while asleep matched that of when they sing. There was a slightly more experimental study carried out by French neuroscientist Michel Jouvet and his team in the 1960s. They inhibited the mechanism in a cat’s brain that prevents movement during sleep, and observed the felines performing actions that they would in a wakeful state, which indicates that they were dreaming of those things. Of course, much about these findings is still very inconclusive, such as answers to questions like, “Do animals remember their dreams as dreams when they're shaken out of their sleep? Can they distinguish the real world from the one in their dreams?”. It is impossible to know what the experience of dreams truly is to beings that are not human, especially when sometimes our own dreams are enough to confound us.

As a whole, the concept of dreams is a thrilling and enigmatic one. Some people are superstitious and interpret hidden meanings in dreams that translate to their real lives. Other people may not dream at all, or simply see dreams as biological phenomena. They have been dubbed a method of “unconscious thinking,” which raises the question of how much we are inevitably controlled by forces that don’t stem from our free will. The question still remains: “When we all fall asleep, where do we go?” The only answer I can give is that we go wherever our minds take us.

Sources :

Aristotle. "On Sleep and Sleeplessness." Translated by J. I. Beare. Written 350 B.C.E. http://classics.mit.edu/Aristotle/sleep.html

Burke, Carolyn. "What Happens in the Brain When We Dream?" BrainWorld, July 31, 2019. https://brainworldmagazine.com/what-happens-in-the-brain-when-we-dream/.

Cohut, Maria. "Lucid Dreaming: Controlling the Stories of Sleep." MedicalNewsToday, July 27, 2020. https://www.medicalnewstoday.com/articles/323077.

Eilish, Billie. WHEN WE ALL FALL ASLEEP, WHERE DO WE GO?, Darkroom/ Interscope Records, 2019. Spotify, https://open.spotify.com/album/0S0KGZnfBGSIssfF54WSJh?si=wVKJEiNhQkGe7De027YgFg.

Goldman, Jason G. BBC Future, April 25, 2014. https://www.bbc.com/future/article/20140425-what-do-animals-dream-about.

Hurt, Avery. "A Glimpse Inside the Mind of Dreaming Animals." Discover Magazine, Jan 20, 2021. https://www.discovermagazine.com/mind/a-glimpse-inside-the-mind-of-dreaming-animals

Langley, Liz. "Do Animals Dream?" National Geographic, September 5, 2015. https://www.nationalgeographic.com/culture/article/150905-animals-sleep-science-dreaming-cats-brains

Marks, Hedy. "Dreams." WebMD, November 05, 2021. https://www.webmd.com/sleep-disorders/dreaming-overview#:~:text=Dreams%20can%20happen%20at%20any,to%20six%20times%20a%20night.

Martins, Kris. "Lucid Dreams." WebMD, August 14, 2022. https://www.webmd.com/sleep-disorders/lucid-dreams-overview

Rand, Paul. "Do Animals Dream? with David M. Peña-Guzmán." Big Brains Podcast. UChicago News, July 21, 2022. https://news.uchicago.edu/do-animals-dream-david-m-pena-guzman#:~:text=But%20rather%2C%20they%20dream%20of,this%20particular%20animal%20has%20had.

Spencer, Rebecca M. C. "The Science of Dreams." Frontiers for Young Minds, December 18, 2019. https://kids.frontiersin.org/articles/10.3389/frym.2019.00140.

Suni, Eric. "Sleepwalking: What is Somnambulism?" Sleep Foundation, October 7, 2022. https://www.sleepfoundation.org/parasomnias/sleepwalking.

"Dream Analysis." GoodTherapy, February 2, 2016. https://www.goodtherapy.org/learn-about-therapy/types/dream-analysis.