Have you ever experienced that heart-pounding moment in a dream when you feel like you’re falling, only to be jolted awake in a sudden rush of adrenaline? It’s a sensation that lingers, leaving you questioning the line between the subconscious world of dreams and the reality of waking life. But what if I told you that this seemingly common experience holds insights into the inner workings of the sleeping mind and our understanding of it?
For centuries, people have pondered the meaning of dreams. Early civilizations thought of
dreams as a medium between the earthly world and that of the gods. The Greeks and Romans were convinced that dreams had certain prophetic powers. It was not until the nineteenth century that we started to have a deeper understanding of dreams; one that includes more than personal interpretations of them.
Dreams serve multiple significant functions: they aid in memory consolidation, transforming
new memories into more permanent forms (as evidenced by post-sleep memory boosts), they offer insights into future events, potentially serving as messages about what to focus on, and recognizing patterns in dreams could provide valuable foresight. Additionally, dreams provide a safe platform for emotional processing, allowing individuals to navigate unresolved feelings and experiences, which promotes emotional well-being.
The Role of REM Sleep Stages
Dreaming manifests across various sleep stages, prominently within Rapid Eye Movement
(REM) and non-REM phases, distinguished by discernible EEG patterns. Healthy sleep cycles
involve multiple repetitions per night.
Non-REM phases denote the transition from lighter to deeper sleep states, where most dreaming occurs, marked by diminished heart rate, body temperature, muscle tension, and slower cerebral waves. Advancing through stages 2 and 3 is vital for feeling refreshed.
REM sleep initiation is triggered by specialized neurons that pump activity straight into the brain cortex, allowing us to experience vision even when our eyes are closed. It features rapid eye movements, heightened cerebral engagement, irregular cardiac rhythm, and fluctuating blood pressure. REM sleep often coincides with vivid dreaming and temporary muscular immobilization. This stage compresses with age, with memory consolidation predominantly during non-REM phases. Neurotransmitter dynamics shift during REM sleep, with elevated acetylcholine release and declined serotonin and norepinephrine secretion.
Moreover, our inclination towards being "early birds" or "night owls" is tied to circadian rhythms and sleep-wake homeostasis, which control our biological clock and monitor the necessary amount of sleep we need.
Regions of the brain involved in dreaming
Hypothalamus: Within it lies the suprachiasmatic nucleus (SCN), housing clusters of thousands of cells that directly receive light information from the eyes, orchestrating your behavioral rhythm. It stands as a pivotal hub for regulating sleep.
Brain stem: Serving as a liaison with the hypothalamus, it governs the transitions between wakefulness and sleep. Within both the hypothalamus and brain stem, sleep-promoting cells produce GABA, a chemical that dampens the activity of arousal centers in the brain, thereby promoting the inhibition of wakefulness.
Thalamus: Serves as a relay station for sensory input into the cerebral cortex, where information is interpreted and processed from short to long-term memory. During most stages of sleep, the thalamus becomes quiet, letting you disengage from the external world.
Basal forebrain: Promotes sleep and wakefulness, while part of the midbrain acts as an arousal system. Cells in this region release adenosine, bolstering your sleep drive. Caffeine counteracts sleepiness by blocking the actions of adenosine.
Amygdala: Central to emotional processing, it experiences heightened activity during REM sleep, highlighting its role in the emotional landscape of dreaming.
Theories of dream formation
Though the formation of dreams is widely debated, the three main theories are the Freudian Psychoanalytic Theory, the Activation-Synthesis Theory, and the Threat-Stimulation Theory.
Freud's psychoanalytic theory suggests that dreams reflect unconscious desires, thoughts, and motivations, including repressed longings such as sexual instincts. He proposed that dreams consist of manifest content (actual images) and latent content (hidden meanings), symbolizing inner conflicts and desires.
Hobson and McCarley's activation-synthesis theory proposes that dreams lack inherent meaning, and are the result of random electrical brain impulses. These impulses draw upon fragmented thoughts and memories, synthesizing them into the narrative of a dream. According to this theory, dreaming is a process of the brain attempting to make sense of these neural activations during sleep.
The threat-stimulation theory posits that dreaming is an ancient biological defense mechanism. It suggests that dreams repeatedly simulate potentially threatening events, enhancing the brain's ability to perceive and avoid threats. By engaging in these simulations, individuals develop and reinforce adaptive responses to potential dangers in their environment.
Why do we forget dreams when we wake up?
Mismatch between dream and waking reality: Dreams frequently diverge from the constraints of physical laws and rationality, often defying the principles of physics and logic. Upon awakening, our rational faculties reassert themselves, rendering these dream experiences as bewildering and illogical.
Absence of narrative structure: Dreams often lack a cohesive narrative structure, resembling a kaleidoscope of disjointed images, emotions, and sensations. This absence of coherence presents a challenge when attempting to recall and recount these experiences.
Rapid evanescence of dream memories: Dreams typically reside in our short-term memory, which is highly volatile. Consequently, dream memories fade rapidly, diminishing their accessibility upon waking.
Lack of immediate attention: The transition from sleep to wakefulness can be abrupt, prompting a shift in focus towards the demands of the forthcoming day. As a result, these fleeting dream moments often escape immediate attention.
Dream amnesia mechanism: Some researchers propose that the mechanism of forgetting dreams serves a protective function. Given that dreams often involve intense emotions and scenarios, their retention could potentially unsettle our emotional equilibrium. Forgetting these experiences thus aids in maintaining psychological balance.
Works Cited
Barbazzeni, B. (2022). While We Dream: The Neuroscience of the Sleeping Brain. [online] ExO Insight. Available at: https://insight.openexo.com/while-we-dream-the-neuroscience-of-the-sleeping-brain/.
Cherry, K. (2023). 7 Theories on Why We Dream. [online] Verywell Mind. Available at: https://www.verywellmind.com/why-do-we-dream-top-dream-theories-2795931.
Eagleman, D. and Vaughn, D. (2020). Why Do We Dream? A New Theory on How It Protects Our Brains. [online] Time. Available at: https://time.com/5925206/why-do-we-dream/.
Holland, J.M. (2018). Importance of Dreams – 5 reasons why they are significant. [online] Infinum Growth Insights. Available at: https://www.infinumgrowth.com/importance-of-dreams/.
National Institute of Neurological Disorders and Stroke (2022). Brain Basics: Understanding Sleep. [online] www.ninds.nih.gov. Available at: https://www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep.
Nir, Y. and Tononi, G. (2010). Dreaming and the brain: from phenomenology to neurophysiology. Trends in Cognitive Sciences, [online] 14(2), pp.88–100. doi:https://doi.org/10.1016/j.tics.2009.12.001.
Uniyal, P. (2023). 5 reasons we forget our dreams after waking up. [online] Hindustan Times. Available at: https://www.hindustantimes.com/lifestyle/health/5-reasons-we-forget-our-dreams-after-waking-up-101696596631327.html#.
van der Linden, S. (2011). The Science Behind Dreaming. [online] Scientific American. Available at: https://www.scientificamerican.com/article/the-science-behind-dreaming/.
Comments