Every night, as the body rests, the brain enters a mysterious state that has intrigued scientists, philosophers, and the curious for millennia. You close your eyes, lose consciousness, and suddenly, you’re flying over an unknown city, meeting people who are no longer here, or trying to escape something you can never clearly see. Waking up with the vivid sensation that it “was too real” is one of the most universal experiences of human existence.
Dreams fascinate because they seem beyond our control — and at the same time, they seem to say something about ourselves. For centuries, cultures around the world have attributed prophetic, spiritual, and psychological meanings to them. Today, neuroscience can explain much of what happens in the brain during sleep, but many questions remain open. What is certain is that dreaming is neither random nor useless: it is a process deeply linked to memory, emotions, and mental health.
In this article, you will understand why the brain produces dreams, what different types of dreams can indicate about your emotional and physical state, what science has discovered — and where it still stumbles over its own questions.
What Happens in the Brain While You Sleep
Sleep is not a uniform state. It is divided into cycles of approximately 90 minutes that repeat throughout the night, and each cycle goes through distinct phases. The main ones are slow-wave sleep (also called deep sleep or NREM — Non-Rapid Eye Movement) and REM sleep (Rapid Eye Movement, or Rapid Eye Movement).
It is during REM sleep that most vivid and narrative dreams occur. In this phase, the eyes move rapidly under closed eyelids, heart rate slightly increases, and the brain shows surprisingly similar electrical activity to the waking state. Meanwhile, the body’s muscles enter a kind of temporary paralysis — a protective mechanism so you don’t physically act out what you’re dreaming.
The prefrontal cortex, the region responsible for logical reasoning and decision-making, is relatively less active during REM. This explains why in dreams we accept absurd situations without questioning — like finding a dinosaur in the office and thinking it’s completely normal. Meanwhile, areas linked to emotions, such as the amygdala, are highly active, which justifies the emotional intensity of many dreams.
Why Do We Dream? The Main Theories
Despite all the advances in neuroscience, the question “why do we dream?” still does not have a single definitive answer. There are several well-founded hypotheses, and it is likely that the function of dreams is multifactorial — that is, it serves more than one purpose at the same time.
The Memory Consolidation Theory
One of the most accepted hypotheses is that dreams help the brain process and consolidate memories. During REM sleep, the brain revisits experiences of the day, selects what should be retained long-term, and discards what is not relevant. Studies with volunteers have shown that people who sleep right after learning a new task perform better on later tests than those who stay awake for the same period.
The Threat Simulation Hypothesis
Finnish neuroscientist Antti Revonsuo proposed that dreams are a kind of risk situation simulator. In ancestral environments, mentally rehearsing how to react to predators or conflicts could increase survival chances. This would explain why dreams of being chased, falling, or in danger are so common in virtually all cultures.
The Role in Emotional Regulation
Matthew Walker, a neuroscientist and professor at the University of California, Berkeley, argues in his research that REM sleep functions as a kind of “night therapy”. During this phase, the brain reprocesses emotionally charged memories in an environment with lower levels of norepinephrine (a hormone associated with stress), allowing difficult experiences to be revisited without the same intense emotional load. When this process fails — as in people with post-traumatic stress disorder (PTSD) — repetitive nightmares may arise as a symptom.
The “Random Noise” Theory
A more skeptical view, proposed by researchers Allan Hobson and Robert McCarley in the 1970s, suggests that dreams are the result of the cerebral cortex trying to make sense of random electrical signals generated by the brainstem during REM. In this perspective, dreams would not have significant content in themselves — they would be just narratives hastily constructed to organize neural impulses without a defined purpose. This theory, known as activation-synthesis, has lost some ground with more recent research but still has defenders.
What Different Types of Dreams Can Reveal
Although dream interpretation is not an exact science — and any individual analysis should be done with caution — some recurring patterns have been studied and associated with specific emotional and physical states.
- Dreams of falling or flying: often associated with feelings of loss of control or, conversely, of freedom and confidence. They may occur during life transitions.
- Dreams of being chased: linked to stress, anxiety, or the feeling of avoiding a problem in waking life.
- Dreams with deceased people: common in grief, may be part of the natural process of dealing with loss.
- Dreams of teeth falling out: one of the most reported worldwide. Studies point to a correlation with high levels of anxiety, but there is no scientific consensus on a single meaning.
- Lucid dreams: those in which the dreamer is aware of dreaming and, in some cases, can control the narrative. Laboratory research has confirmed that these dreams do exist — trained participants managed to communicate with researchers through eye movements during the lucid state.
- Frequent nightmares: when recurrent and disturbing, they may be a sign of high stress, anxiety, depression, or PTSD. In such cases, it is important to seek professional evaluation.
> Attention: the above associations are general and educational information. If you experience frequent nightmares, sleep disorders, or symptoms that affect your quality of life, consult a doctor or mental health professional.
How Long Does a Dream Last — and Why We Forget Almost Everything
A single REM cycle can last from 10 to 30 minutes, and over a full night’s sleep, you can have four to six dream episodes. Mathematically, this means you spend between one and two hours dreaming every night — even if you wake up without remembering anything.
Forgetting happens because, during sleep, the hippocampus — a structure fundamental for forming new memories — operates differently from the waking state. Unless you wake up during or right after a REM phase, the dream doesn’t get “recorded” in an accessible way. This is why people who have very fragmented sleep often report remembering more dreams: multiple awakenings create recording windows.
If you want to remember more of your dreams, you can try these practices:
- Keep a notebook or note-taking app by the bed.
- Upon waking, stay still for a few seconds before moving.
- Immediately record any fragment, even if it seems nonsensical.
- Avoid checking your phone before writing down — visual stimulation can quickly erase dream residues.
- Try to wake up naturally, without an alarm, on days when possible.
Dreams Throughout Life: From Childhood to Old Age
The way we dream changes as we age. Young children spend a higher proportion of sleep time in the REM phase — newborns spend up to 50% of their time in this phase, compared to about 20% in adults. It is believed that this intense REM in the early years of life is related to the accelerated development of the nervous system.
Adolescents tend to have dreams with greater emotional and social content, reflecting the period of intense identity formation. In older adults, REM sleep time tends to decrease, as does the frequency of nightmares — although people with neurodegenerative diseases, such as Parkinson’s, may experience a disorder called REM sleep behavior disorder, where the typical muscle paralysis of the phase does not occur correctly.
The Boundary Between Science and Interpretation
Since Sigmund Freud, who published The Interpretation of Dreams in 1899, and Carl Jung, who developed his theories on the collective unconscious in the early 20th century, psychoanalysis has attributed a central role to dreams in understanding the human psyche. For Freud, dreams were the disguised fulfillment of repressed desires. For Jung, they were messages from the unconscious, laden with universal symbols called archetypes.
Modern neuroscience neither confirms nor entirely refutes these views — it simply operates on another level of analysis. What brain imaging studies show is that dream content is influenced by concerns and emotions from the waking state, which in a way dialogues with psychoanalytic ideas without validating their complete interpretive systems.
The fact is that the boundary between what dreams “mean” in psychological terms and what they “do” in neurological terms is still being mapped. And perhaps part of the fascination with dreams lies precisely in this: they exist in that space between the measurable and the ineffable.
Conclusion
Dreaming is, at the same time, a sophisticated biological process and one of the most subjective and personal experiences a human can have. Science has shown that dreams fulfill real functions — consolidating memories, regulating emotions, possibly preparing the organism to deal with difficult situations. But the symbolic richness, strangeness, and emotional intensity they carry continue to be a territory of fascination and investigation.
If you’ve ever woken up disturbed by a nightmare or with the longing for someone who appeared in the dream, know that you’re not alone — and that there is a neurological and emotional reason behind it. The brain doesn’t stop when you close your eyes. It works, processes, organizes, and occasionally tells stories that only make sense in the language of the unconscious.
Next time you wake up with a dream on the tip of your memory, it’s worth jotting it down. Not because dreams predict the future or reveal absolute truths, but because they are a window — imperfect, blurry, and fascinating — into the workings of your own mind.
- Dreams of being chased: linked to stress, anxiety, or the feeling of avoiding a problem in waking life.
