Dreams have been an endless source of wonder and fascination throughout recorded history. In ancient times, dreams were believed to be a time of channeling insight from the gods. Nowadays, several theories from psychology and neuroscience have been proposed to explain the function of this mysterious nightly phenomenon.  


In this article, we’re going to take a closer look at the function of dreams and dream sleep. You may have noticed after starting Remrise that your dreams are more frequent and vivid. We’ll end by exploring the causes of vivid and lucid dreams. 


Dream interpretation is part and parcel of the examined life. Learn more about dreams and what they may mean in our related article found here.

When do we dream?

Even if you don’t remember your dreams, we all dream every night when we drift off to sleep. We spend about three-quarters of the total sleep time dreaming. Although REM sleep (Rapid Eye Movement sleep) is usually the sole phase of sleep associated with dreaming, we dream in both REM and non-REM, or NREM sleep


Our most vivid, emotional, and bizarre dreams occur in REM sleep, which makes up about 20-25% of the total sleep time. REM sleep is characterized by rapid eye movements, higher heart rate and respiratory activity, as well as brain activity that closely resembles wakefulness. NREM, which makes up the majority of the total sleep duration, has high rates of dreaming as well, believed to be between 50-80%. However, successful dream recall is much higher when we awaken from REM sleep as opposed to NREM sleep.

What is the function of dreams? 

Up until the early 20th century, dreaming was viewed largely through a psychological lens. Sigmund Freud believed dreams were the “royal road to the unconscious,” made up of symbolic content that fulfilled our unconscious wishes. Later, the famous psychologist Carl Jung revised Freud’s theories and believed dream interpretation, with their mythic storylines, played a fundamental role in integrating our conscious and unconscious minds.


Although many believe analyzing dreams can reveal ourselves to ourselves, the highly subjective nature of dream interpretation has made it difficult to form a generalizable theory of why and how we dream.


Later in the 20th century, modern brain imaging and recording techniques have given rise to refined and scientifically-testable theories of dreaming. These advancements have shifted the study of dreams into the hands of neuroscientists. 


Although still largely a mystery, researchers are increasingly getting at the why and how of dreaming. However, the scientific consensus on the precise function of dreaming is still not fully apparent.

Dreams are a byproduct of nightly neural chatter

Some scientists claim dreams don’t serve a primary purpose but instead arise from the electrical impulses in the brain, making them a meaningless byproduct of neural activity as connections are sorted through.


In this theory, called the activation-synthesis theory, neural impulses originating from deep in the brain are interpreted by higher up brain regions, namely the cerebral cortex. Dream storylines then emerge as our brain attempts to make sense of this neural activity.

Dreams help us solve problems

Since our minds are unconstrained by reality while we dream, they may function to help us solve problems that we otherwise wouldn’t solve during wakefulness. According to Dr. Bob Stickgold, Director of the Center for Sleep and Cognition at Harvard Medical School: 


“Dreaming doesn't seem to be goal-oriented. Dreaming seems to be more about exploring possibilities than finding the correct answer to something. Let's call it the divergent thinking, as opposed to convergent thinking.” 


Dr. Stickgold continues, “Our thoughts are, that the actual function of dreaming is really about exploring that “solution space”, as you would say in mathematics: the range of possible ways to look at, or think about a particular problem.” 


Dr. Stickgold refers to this function of dreaming with the acronym “NEXT UP”, or “Neuro Exploration to Understand Possibilities”. Given that numerous scientific discoveries are attributed to dreams, interpreting one’s dreams the morning after might just be one of the most potent ways to gain insight into a problem. 

Dreams may play a role in memory reactivation and consolidation

Research in animals and humans have supported the idea that REM sleep is essential to remember and incorporate relevant experiences for long-term storage while stripping away the experiential junk we no longer need. Dream storylines might be this neural process writ large. During REM sleep, the brain can integrate snippets of past experience with existing knowledge, helping us to form a coherent narrative from what we have learned the day before. 


Neuroimaging studies have confirmed that REM sleep is critical in order to assimilate new knowledge. Brain regions involved in learning light up again when we enter REM sleep, and when subjects are tested on what they learned before a night of sleep, they do much better than if they are deprived of REM sleep. Dreams, and more broadly dream sleep, may therefore play a crucial role in the processing of past memories and may better prepare individuals for the future.

Dreaming heals our emotional wounds 

According to Dr. Matthew Walker in his bestselling book Why We Sleep, dreaming is a form of overnight therapy. Beyond helping us solve problems, dream sleep helps us process emotional memories and heal our emotional wounds. This theory is well-supported by neuroimaging studies. Emotional regions of the brain, collectively called the limbic system, are 30% more active during REM sleep compared to wakefulness. 


One mechanism thought to account for this function involves the brain’s ability to tag emotionally salient memories that are in need of processing during dream sleep. In this way, the most intense memories can be identified, regulated, and incorporated without the strong emotional charge in which they were initially formed. 


Perhaps it’s no coincidence that a form of trauma therapy called EMDR, or Eye Movement Desensitization and Reprocessing, fundamentally involves rapid eye movements similar to what occurs during REM sleep. However, REM sleep has the added benefit that the levels of stress neurotransmitters such as norepinephrine and cortisol are much less during this period, which helps to take the edge off emotionally painful experiences. 

When dreams turn lucid and vivid

Have you ever had a dream where you knew you were dreaming? When this happens, it’s not uncommon to immediately jump on the urge to start flying around. Maybe you’ve also had a dream that felt so vivid and real that when you awoke you were dead certain that it actually happened.


Lucid dreams are vivid dreams in which the dreamer can control aspects of the dream. Not getting enough sleep, especially REM sleep, can lead to a phenomenon called REM rebound where the brain tries to "make up" for lost dream sleep, leading to more intense dreams. 


While vivid dreams are usually sought after, if you find vivid dreams are disturbing you, be sure to stick to a consistent sleep schedule and follow a regular sleep routine. Certain sleep supplements, such as valerian root, melatonin, 5-HTP, and galantamine may also produce vivid or lucid dreams in some individuals. Additionally, some sleep disorders like narcolepsy can lead to vivid dreams. Individuals with narcolepsy enter deep dream sleep very quickly, which can result in vivid dreaming. 


For those that want to explore lucid dreaming, keeping a dream journal is one effective way to gain awareness of dreaming. Try recounting all you can remember about your dreams right upon waking up by either writing them down or speaking into a voice recorder. With practice, you’ll be able to recount long dream storylines and have a higher chance of recognizing when you’re in a dream.


Optimal dreaming relies on a consistent sleep schedule as well. When we consistently get seven to nine hours of quality sleep, we achieve the five to six REM cycles we crucially need for dreaming. With the Remrise app, you can trend your sleep habits with the sleep diary function. Simply log your sleep ritual each day in thirty seconds and the app will keep track of the important variables that lead to your best sleep and best dreams.  

Glossary

Cerebral cortex: The thin layer of the brain that covers the outer portion of the cerebrum. The cerebral cortex is divided into four major lobes: the parietal lobe, temporal lobe, occipital lobe, and frontal lobe.


REM rebound: The lengthening of duration and frequency of REM sleep cycles following periods of REM sleep deprivation. REM sleep deprivation is commonly caused by either REM-suppressing drugs (such as alcohol and marijuana) or sleep loss. 


References

Givrad, S. Dream Theory and Science: A Review. Psychoanalytic Inquiry (2016), 36(3), 199–213


Siegel, J.M. The REM Sleep-Memory Consolidation Hypothesis, Science (2001): Vol. 294, Issue 5544, pp. 1058-1063.