The Stuff That Dreams Are Made Of
Understanding the Science of Dreams
Today's newsletter is a departure from our usual content. Rather than diving into the complexities of today's public health policies and healthcare debates, we're picking the brain of Unbiased Science's resident neurobiologist, Dr. Sarah Scheinman, to discuss the science of dreams. Honestly, we needed a break— time to flip to the cooler side of the pillow.
In a world where public health discussions can feel heavy and overwhelming, sleep offers a welcome escape from the healthscape; a beautiful retreat from reality and a chance to explore our wildest imaginations. So let's step away from policy papers and step into the mysterious realm where our minds wander freely each night, crafting stories that are sometimes bizarre, often emotional, and always fascinating. You’re getting sleepy….
"We are such stuff as dreams are made on, and our little life is rounded with a sleep." — Shakespeare, The Tempest
We spend nearly one-third of our lives asleep—a staggering portion of our existence devoted to a seemingly inactive state. But this time is far from wasted. In fact, sleep is one of the most essential and evolutionarily conserved biological processes. As sleep research pioneer Dr. Allan Rechtschaffen famously stated, "If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made." And he was absolutely right. Far from being a passive shutdown, sleep is a highly active and complex state during which the brain and body carry out a host of critical restorative processes. These include cellular and tissue repair, immune system support, metabolic regulation, hormone balancing, and the clearance of toxic waste from the brain through the glymphatic system. Sleep also plays a fundamental role in learning and memory, particularly through the consolidation of information gathered during the day.
Yet, for all we know about the importance of sleep, one of its most mysterious and captivating elements continues to puzzle scientists and philosophers alike: dreaming. Why do we dream? Is there a purpose behind the strange, vivid narratives our minds create during sleep? Could dreams carry meaning, or are they simply random neural firings? These are questions that have intrigued scholars for centuries, and while modern neuroscience has provided some insights, the science of dreaming remains one of the most fascinating frontiers in sleep research.
When do we dream?
To understand how we dream, we must first understand how we sleep. Sleep is not a uniform state; rather, it is a dynamic process that cycles through several distinct stages that are defined by different electrical signaling patterns in the brain. In general, there are two main stages of sleep: Non-Rapid Eye Movement (NREM) sleep and Rapid Eye Movement (REM) sleep. Each cycle lasts ~90-110 minutes and repeats multiple times throughout the night. During NREM sleep, the body focuses primarily on physical restoration. While dreams can occur during these stages, they are usually vague and less memorable. Conversely, the most vivid and emotional dreams occur during REM sleep, when brain activity increases and eyes move rapidly under closed lids. REM sleep is especially important for memory, learning, and emotional regulation. REM sleep becomes longer in the second half of the night, which is why we often remember our dreams when we wake up in the morning.
What is a dream?
Scientifically, dreams are thought to be the brain's attempt to process, integrate, and make sense of information, ranging from daily experiences to deep-seated memories. Indeed, dreaming is a cognitively active state. Neuroimaging studies have shown that while we dream, several brain regions become extremely active, including the amygdala (involved in emotion), hippocampus (associated with memory), and visual cortex. Conversely, areas of the dorsolateral prefrontal cortex, responsible for executive functioning, reasoning, and self-awareness, are relatively inactive during REM sleep, which is why dreams can be emotionally intense and visually rich, but often illogical and fragmented.
Why do we dream?
The function of dreaming remains a hot topic of scientific debate. Theories range from the activation synthesis hypothesis, which states that dreams are the brain's attempt to make sense of spontaneous neural activity in the cortex during REM sleep, to the threat simulation theory, which states that dreaming functions as a "virtual reality" rehearsal space for dangerous situations. Additionally, the emotional regulation theory of dreaming posits that dreams might help us process emotional experiences and regulate mood by reprocessing emotional memories in a less reactive state. Finally, although not evidence-based, we have the psychodynamic theories of dreaming. Freud famously proposed that dreams are the "royal road to the unconscious," expressing repressed desires, fears, or conflicts in symbolic form. Although most dream researchers today have moved away from this theory, some still consider dreams to be reflections of inner psychological states or unresolved emotions.
The mystery continues
Dreams remain one of the most compelling enigmas of human experience—a nightly voyage into worlds shaped by memory, emotion, and imagination. While modern neuroscience has illuminated many of the biological processes underlying sleep and dreaming, we've barely scratched the surface of understanding why our minds conjure such elaborate stories each night.
Perhaps that's part of their magic. In a field where we can often explain the mechanisms behind complex biological processes, dreams remind us that some aspects of human experience still hold profound mystery. Whether they serve critical functions in memory consolidation and emotional processing, or simply reflect the beautiful chaos of an active sleeping brain, dreams offer something increasingly rare in our data-driven world: wonder.
As we continue our usual coverage of public health policy and healthcare debates, it's worth remembering that some of the most important aspects of health happen not in hospitals or policy meetings, but in the quiet sanctuary of sleep—where our minds are free to wander, process, and perhaps even heal in ways we're only beginning to understand.
Sweet dreams, and thanks for taking this journey with us into the fascinating world of sleep science.
Stay curious,
Unbiased Science
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I love sleep (as a subject of study and to experience it). It’s such a fascinating topic and has so many important functions in our body! As a pediatrician it’s one of the things that I am constantly reminding parents and children and explaining the why.
Thanks for the piece and welcomed the shift as well!
You dismiss the psychodynamic theory of dreams as not evidence-based but present no evidence for the more materialist theories you say are more favored by scientists. This looks like bias to me. I'm very interested in what would constitute evidence in this inquiry.