Why Do Humans Dream?

A specific evolutionary purpose of dreams is yet to be determined, but research suggests that they help in processing emotions, organizing information in the brain, prepping the body for threats, and facilitating creative tendencies.

Reading Time: 5 minutes

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By Laurina Xie

Mesopotamians were the first people to articulate the concept of a dream: around 5,000 years ago, they recorded their dreams on clay tablets and began to wonder what they meant. Later, Greeks and Romans believed dreams were messages sent from deities or deceased people to predict the future. From then on, specific cultures began to practice dream incubation to cultivate dreams of prophecy. Then, in the early 1900s, Sigmund Freud’s theory that dreams are manifestations of our deepest anxieties and desires led to further debate among psychologists. From the beginning of early civilization formation, society has sought to figure out the function of dreams.

Dreams are hallucinations that occur during certain stages of sleep, most prominently during the rapid eye movement (REM) stage when the brain is least likely to recall them. They are images, thoughts, or feelings that tend to be autobiographical; that is, they are based on recent sentiments, experiences, and issues. Many studies have shown that the waking lives of humans have great influence on the content of dreams. For instance, pregnant women dream more about pregnancy and childbirth, hospice workers often dream about the experiences of caregiving, and musicians dream twice as often about music as non-musicians do. Sometimes, an experience from life takes the form of a dream after several days, or even a week, in a phenomenon known as dream lag. However, we also have the capacity to dream beyond waking experiences. The paralyzed may have dreams in which they walk, swim, and run, and the deaf dream of hearing.

There are several dream classifications. One type is the nightmare: frightening dreams that result in awakening from sleep. They are distinct from bad dreams in that they rarely occur. They can be triggered by stress, emotional upheaval, traumatic experiences, or occur as side effects of medications. Nightmares can contribute to insomnia, daytime fatigue, depression, and anxiety. Junior Shriya Anand recalled a time where a frightening nightmare affected her performance in school the next day: “I had a nightmare that I was in a dystopian society in a forest and someone was chasing after me. Eventually, I reached the end of the forest and fell off a cliff. That woke me up, and after that, I was too paranoid to go back to sleep. The next day at school, I was falling asleep in all of my classes.”

The second type of dream is the night terror: very intense episodes of fright that tend to occur during non-REM dreams, unlike nightmares. Children are more prone to experiencing night terrors. Evidence suggests that there may be a genetic predisposition to night terrors and a relationship among night terrors, sleep apnea, and enlarged tonsils in children.

Third, recurring dreams are dreams that appear with some pattern of regularity. They may contain more threatening content than regular dreams and can be a sign of psychological distress. Junior Paige Wolfing remembered a time in her childhood: “When I was younger, I used to dream of crocodiles eating my family or a shark eating me in a swimming pool.”

Finally, lucid dreams are dreams in which dreamers are aware that they are dreaming and can control or manipulate their dreams. Lucid dreamers display significantly higher brain wave frequencies and increased activity in parts of the frontal lobe, the area of the brain which is deeply involved with conscious awareness, a sense of self, and language and memory. Many people try to induce lucid dreaming, but it can result in sleep paralysis. Junior Tashfia Noor recounted a time where she was able to lucid dream: “I was having a dream where I could fly, and slowly, I began to realize that it wasn’t real. I took control of the dream, and I flew all the way to space. I could see the entire solar system, and it was a freaky feeling.”

Obviously, there are also normal dreams. Junior Maggie Jin said, “I had a dream [in which] I was going to an ice cream store, ordering an ice cream, and sitting down at a table with it, but then I woke up right as I was about to eat it. I was so disappointed when I woke up.” Dreams can also be normal everyday activities.

Dreams may act as methods to confront emotional issues in reality, train the body for fight-or-flight reactions, facilitate creative tendencies, or help store important memories. While asleep, the brain makes connections between feelings that the conscious mind is unable to form because it works on a more logical basis while awake, prohibiting emotional growth during the day. In addition, during dreams, the amygdala is very active. It is the part of the brain that is associated with survival instinct and the fight-or-flight response, and its engagement during dreams signals preparation for a real-life threat. Dreams help facilitate creative tendencies because thoughts and ideas aren’t restricted by the logic filter activated in waking life. Lastly, research shows that dreams can act as memory aids by helping store memories, rid the mind of unimportant memories, and sort through complicated thoughts and feelings by blocking out stimuli that could interfere with memory and learning.

The role of sleep is vital in regulating metabolism, blood pressure, brain function, and other aspects, but the evolutionary purpose of dreams is something that continues to spark debate. Sigmund Freud claimed that dreams are a neurotic symptom stemming from the unconscious mind to keep the body asleep. He also argued that a set of censors transforms latent content, repressed thoughts, and wishes from the unconscious into the content of dreamwork. The main censors are displacement, condensation, representation, symbolism, and secondary revision. More specifically, these censors can work in dreams to displace elements of our experience into characters of lyrics, condense longer narratives into short stories, transform ideas across different mediums, cloak personal experiences in daily life, and refine emotions and thoughts collected from waking life.

Psychiatrist and dream researcher Allen Hobson, in sharp contrast to Freud, argues that dreams do not have an evolutionary purpose and are essentially meaningless. On the other hand, psychoanalyst and neuropsychologist Mark Solms demonstrated a more complex relationship between REM sleep and dreaming in which the seeking system is the generator of dreams. The seeking system is one of the seven major emotional tendencies of the brain and is the system responsible for our motivated actions in relation to survival and our desires. Solms argues that dreams are states of the mind seeking meaning and are motivated psychological phenomena that can enlighten us about our own minds.

Scientists have managed to agree that dreams can be affected not only by health conditions, diet, and daily activities, but also by stress. Stuyvesant students who experience stress on the daily may be susceptible to hyperarousal, which upsets the balance between sleep and wakefulness, making it more difficult to fall asleep and stay asleep. Research shows that daily mild stress increases REM sleep, which is linked to a deficiency in the regulation of the hormone cortisol, a stress hormone. Therefore, stress may trigger more frequent dreams, and more specifically, anxiety-ridden dreams. However, if students spend time winding down before bed, schedule time to write down all their concerns, and practice relaxation techniques, they can control their stress and as a result, enjoy more dreams about eating ice cream rather than getting eaten by alligators.