PDF Summary:This is Why You Dream, by Rahul Jandial

Why do we spend a third of our lives dreaming? In This Is Why You Dream, neurosurgeon Rahul Jandial argues that dreams aren’t random mental noise—they’re essential neurological processes that keep your thinking flexible, process difficult emotions, spark creative breakthroughs, and help form your identity. Through firsthand observations and cutting-edge research, Jandial explains how dreams work, what they reveal about your inner life, and how you can actively shape them.

Learn to interpret your dreams using a two-step method based on brain science, manage recurring nightmares, harness sleep states for creative problem-solving, and even practice lucid dreaming—becoming aware you’re dreaming while asleep. Further, discover how REM and non-REM sleep work together, whether dream advertising actually works, and how Jandial’s techniques connect to practices from sleep researchers and Buddhist monks alike.

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But this efficiency creates what Hoel sees as an overfitting problem: a concept from statistics where a model becomes so closely tuned to a dataset that it fails when it encounters new data. For example, if you see only the same 12 people daily, your face-detecting neurons would become great at recognizing those 12 people, but poor at distinguishing between unfamiliar faces. Similarly, if you always travel the same route, you’ll struggle to navigate detours. The hippocampus, which plays a crucial role in forming memories, helps solve this by deciding which patterns are general enough to store long-term in the neocortex and which stay as unique episodic details in the hippocampus.

During dreaming, the hippocampus coordinates the reactivation of remembered patterns across brain regions. But the dreams it creates go beyond replaying the actual experiences you had in real life and involve imagined scenarios you never encountered. These “corrupted” versions of actual memories activate unusual combinations of neural patterns, preventing your brain’s representations from becoming too narrow—and helping your brain stay flexible and better at making sense of unfamiliar situations in waking life.

Dreams Help You Process Your Emotions

Second, Jandial explains that dreams help you process difficult emotions without the anxiety normally attached to them. When you experience something emotionally challenging while awake, adrenaline surges through your system, binding the emotional content to a stress response. But, as we explored earlier in the guide, adrenaline levels drop to zero when you’re dreaming, so you can re-experience the memory while defusing its emotional charge. For example, research on divorcing couples found that those who had complex dreams mixing old and new memories recovered better from depression than those who didn’t. The dreams helped process negative feelings, allowing people to move forward through a major life change.

(Shortform note: Research reveals how dreams prevent two problems that plague emotional processing when you’re awake: rumination and overreaction. In REM sleep, neurons actively process emotional memories—their dendrites fire, encoding whether something is safe or dangerous—but the nerve cell bodies that would trigger action remain silent. This explains why people who dream show reduced emotional reactivity the next day: They practiced processing threats without the rumination spiral or stress response that would occur while awake. You can achieve similar results in reducing your reactivity with mindfulness meditation, learning to notice emotions as physical feelings rather than getting lost in anxious or angry thoughts about them.)

Dreams Help You Rehearse Important Scenarios

Third, Jandial explains that dreams create simulations that help you prepare for real-world challenges. Being chased, attacked, or facing threats are common dream themes, and this threat rehearsal during dreams helps you work through problems you might encounter. Jandial notes that dreams also serve as social laboratories: Your brain creates varied scenarios involving realistic and improbable social situations, allowing you to explore how interactions might unfold. This makes evolutionary sense because our survival has always depended on navigating complex group dynamics. The medial prefrontal cortex, which handles social cognition, remains active during dreams precisely to enable these social simulations.

(Shortform note: The social scenarios and physical threats that dreams rehearse have a lot in common on the neurological level. Research shows that the brain processes social rejection using the same neural regions involved in physical pain. Your brain takes social rejection seriously, even in situations where the stakes are low, because your brain evolved over six million years when social rejection could literally mean death. During that time, evolution co-opted the existing physical pain system to handle social threats rather than creating an entirely new warning system. Your brain still runs on this ancient programming and can’t distinguish between ancestral life-or-death rejection and modern social discomfort.)

Dreams Spark Creativity and Problem-Solving

Fourth, Jandial argues that dreams enable you to practice divergent thinking: seeing problems from new angles and discovering unexpected connections. With your Executive Network offline, your Imagination Network has the creative freedom to make breakthroughs. Jandial explains that the dreaming brain excels at visual problem-solving. The sleep-entry period (the few minutes as you’re falling asleep) and sleep-exit period (the first minutes after waking) are particularly fertile for creativity because these are transitional states where your Executive Network is partially online but your Imagination Network is also operating freely, giving you both creative freedom and enough conscious control to capture and evaluate ideas.

Why Are You Most Creative While You’re Half-Asleep?

The sleep-entry and sleep-exit periods facilitate creative thinking because of what happens in your brain during these transitions. In the first stage of sleep, called N1, executive control relaxes and your brain makes wider-ranging connections. But at the same time, you retain just enough conscious control to notice and remember these insights. The transition happens gradually: As you fall asleep, deep brain regions like the hypothalamus shut down first, followed by the thalamus. Finally, the cortex shuts off from front (areas involved in planning and decision-making) to back (areas involved in sensory processing). The whole process can take tens of minutes.

As this transition plays out, you experience dreamlike thoughts layered over your awareness of the real world—you’re caught between dreaming and waking. Research confirms that this state boosts creative thinking: People who spent just 15 seconds in N1 sleep were three times more likely to solve a creative math problem, and when researchers prompted people to dream about a specific topic during N1 sleep, they performed 43-78% more creatively on related tasks afterward. The same gradual transition happens when waking: Your cortex reactivates from front to back over several seconds, and recovering your full cognitive abilities can take minutes to an hour.

Dreams Help Form Your Identity

Finally, Jandial argues that dreams help you form your sense of self, especially during childhood. Children don’t begin dreaming until age four or five, coinciding with the development of visual-spatial skills and emerging self-awareness. Nightmares arrive shortly thereafter and serve a specific developmental function: The dream-self faces attack from monsters or evil beings, helping children to establish boundaries between themselves and others and to see themselves as an individual with their own thoughts. Even in adulthood, dreams support your evolving self-understanding by revealing preoccupations and values that your conscious mind hasn’t fully acknowledged.

From Childhood Nightmares to Adult Empathy

Determining exactly when children begin dreaming is challenging because researchers can only study what children can report, not what they actually experience. Babies spend a large proportion of their sleep in REM sleep, the stage where adults dream most vividly. Some researchers interpret this as evidence that babies probably dream even more frequently than older children. But toddlers under two lack the language skills to describe dreams, and children under four struggle to distinguish dreams from reality or to remember dreams upon waking—partly because in early childhood, our brains have a limited capacity to form and retrieve episodic memories.

The boundary between self and others that Jandial says nightmares help establish becomes foundational to social functioning throughout life. Recognizing yourself as a separate consciousness enables “theory of mind”—the ability to understand that others have private mental lives—which typically develops between ages three and five. In childhood, this lets you interpret others’ behavior, communicate effectively by explaining information that others don’t know, and feel empathy by imagining how others feel rather than assuming they feel what you would.

These same skills remain essential in adulthood: You use them to read between the lines in conversations, anticipate how others might react, and detect when someone is masking their true emotions. When dreams reveal aspects of your own thoughts and values you haven’t consciously acknowledged, as Jandial argues they do, those insights don’t just clarify who you are; they also deepen your understanding of others by making you more aware of the complexity and range of inner life that all people experience. The self-other boundary that childhood nightmares may establish serves you throughout life: Understanding your own distinct mental life remains essential for understanding others’.

How Can We Work With Our Dreams?

Understanding why we dream reveals that dreams serve crucial functions—but that doesn’t mean every dream feels helpful. Nightmares can leave you shaken, anxiety dreams can linger all day, and confusing dreams can make you wonder what your brain is trying to tell you. Sometimes dreams feel like they’re working against you. Fortunately, you can learn to work with your dreams in two complementary ways: by interpreting what they reveal about your inner life, and by actively shaping your dream experiences to better serve your needs.

1. Remember Your Dreams

To work with your dreams—to interpret them or shape them—you must remember them. Jandial explains how to improve your dream recall: Before you go to sleep, tell yourself that you’ll dream, remember your dream, and record it upon waking. This primes your brain to prioritize dream retention. Upon waking, write down or voice-record whatever you remember before thinking about your day or checking your phone. The dreams you recall in the morning come from your final REM cycle, which Jandial argues is the most emotional and symbolically rich period of dreaming. Protecting this morning window before distractions intrude can help you gain valuable insight from your dreams.

Why Some People Remember More of Their Dreams

Research shows dream recall varies dramatically between people, in part because dream memories are fragile. Brain regions that transfer memories into long-term storage are deactivated during sleep, while those involved in short-term memory remain active, but can only retain information for about 30 seconds. So unless you wake up from REM sleep and immediately focus on what you were dreaming about, it never enters long-term storage.

People who frequently remember their dreams wake up more frequently throughout the night—spending roughly twice as much time awake during the night as those who rarely recall their dreams. These brief awakenings, often lasting just one or two minutes, enable the brain to transfer dream memories from short-term to long-term storage.

But sleep patterns don’t fully explain the differences: Even controlling for wakefulness, people with a positive attitude toward dreams remember more of their dreams. This suggests that paying attention during those brief waking windows matters as much as having them. Plus, as Jandial points out, the dreams you have in the morning occur during your final REM cycle. Many experts agree with Jandial that keeping a dream journal, or even reading about dreams, increases your recall, likely by encouraging you to pay more attention as you wake up.

2. Interpret What Your Dreams Reveal

Not every dream needs interpretation. Jandial explains that some dreams have obvious meanings: Dreaming about an exam before taking one clearly reflects your anxiety about it. Others are tied to major life stages like pregnancy or approaching death, where meanings are self-evident. Some dreams lack emotional intensity and are just mental static. The dreams worth examining are those with powerful emotions, distinct central images, and coherent narratives. These dreams are shaped when your limbic system is in overdrive and can reveal concerns that aren’t obvious to you during your waking life. Jandial proposes a two-step method of dream interpretation.

The first step is to identify the dominant emotion and its intensity. What was the strongest feeling, and how intense was it? Greater intensity indicates a more important dream. The emotions you experience during waking hours shape your dreaming, but the images and plot of the dream can match the emotion while having little connection to its real source.

The second step is to consider the dream’s central image as a metaphor. While you’re dreaming, your brain searches through your memories for other times when you experienced similar emotions and conjures images from those experiences. Jandial explains that this is why universal dream dictionaries that claim specific symbols have fixed meanings don’t work: The same image means different things to different people. Only you can interpret your dreams because only you know your associations, memories, and emotional landscape.

What Do Dreams Really Mean?

Scientists disagree about whether dreams have meaning or are just neural noise. The activation-synthesis theory proposes that dreams result from the brain trying to make sense of random electrical signals during REM sleep, which suggests dreams are just byproducts of brain activity. In contrast, the psychoanalytic theories of Sigmund Freud (The Interpretation of Dreams) and Carl Jung argue that dreams reveal our unconscious desires in their images. A middle ground is the continuity hypothesis, which argues that dreams reflect our waking concerns and emotions without being deeply symbolic. This may be supported by research showing that about 65% of our waking experiences can be identified in our dreams.

Even if you lean toward the activation-synthesis view that dreams are random and have no inherent meaning, Jandial’s method of focusing on dominant emotions remains useful. Because the limbic system (emotion center) is hyperactive during REM sleep, the emotions you experience in dreams—even if they’re triggered by random neural activity—likely reflect your actual emotional state and concerns as you sleep. In this sense, examining which emotions dominate your dreams can reveal patterns in your emotional life, regardless of whether the dream narrative itself has a deeper symbolic meaning.

3. Consider What Different Types of Dreams Can (and Can’t) Tell You

Jandial explains that what a dream can and can’t tell you depends on what kind of dream it is.

Nightmares in adults vary in significance. Occasional nightmares around stressful events are normal. But if you suddenly start having nightmares when you previously didn’t, or if nightmares increase in frequency, this can signal issues. Jandial explains that you can think of nightmare patterns as a vital sign for your mental health—changes in frequency or intensity deserve attention. For trauma-related nightmares, the dream’s form indicates your progress: When dreams replay the trauma, you’re still struggling to process the experience. When dreams become more metaphorical, this indicates that you’re processing the associated emotions in a healthier way. This evolution from realistic to symbolic dreams signals psychological healing.

Erotic dreams don’t typically signal hidden desires or relationship problems, even when they involve infidelity. Research shows that erotic dreams rarely reflect our waking sexual life: Most feature familiar people from daily life rather than fantasy scenarios. What these dreams do reveal is information about relationships through the emotions they generate when we’re awake and remember them. In healthy relationships, infidelity dreams have minimal effect on next-day intimacy. In troubled relationships, they correlate with decreased intimacy the following day, likely because they highlight the gap between the dream and difficult reality.

(Shortform note: Whether dreams feel distressing or benign often depends less on their content than on what you believe they reveal about you. Some people enjoy their nightmares, just as some people like horror movies, while others become anxious about similar dreams, particularly when they believe nightmares predict future events or reveal psychological problems. Similarly, erotic dreams can cause distress when people interpret them as revealing hidden desires or sexual identities, even though researchers emphasize these dreams rarely reflect literal truths about sexuality. This suggests that Jandial’s emphasis on realizing that not all dreams require interpretation may protect against the anxiety that can come with over-interpreting dreams.)

Some dreams warn about physical or mental health issues. Jandial cites the example of dream enactment behavior, where people act out their dreams because the normal sleep paralysis mechanism fails during REM sleep. Men in their fifties who develop this condition have a 97% chance of developing Parkinson’s disease or related neurological conditions within 14 years. Depression also affects dream content: People with major depression experience nightmares more than twice as often as others, and increasing nightmare frequency can indicate declining mental well-being even before other symptoms become apparent.

(Shortform note: Dream enactment behavior is now widely accepted as a strong marker for Parkinson’s, and frequent nightmares have been shown to correlate strongly with mental health decline. But why dreams can warn of neurological problems remains mysterious. Research on “prodromal dreaming,” or dreams alerting us to health issues before diagnosis, is still controversial, with no established theory explaining how the body would send such signals to the dreaming brain. Some researchers have documented cases of people dreaming about cancerous spots, but there’s limited evidence that dreams reliably warn of problems outside the nervous system.)

4. Use Your Dreams to Think More Creatively

One of the most practical ways to work with your dreams is to put your dreaming brain to work on problems you’re trying to solve. To use the sleep-entry period to think creatively, clearly define a problem and think about it as you drift off, keeping a journal nearby to capture your insights. To take advantage of the sleep-exit period, Jandial recommends resisting the temptation to check your phone as soon as you wake up. Instead, linger in the drowsy state and let your mind wander. To use strategic naps to boost your problem-solving, take a 60- to 90-minute nap so you can experience REM sleep, which weaves new information together with past experiences, creating networks of new associations.

How REM and Non-REM Sleep Work Together for Creativity

Jandial’s emphasis on using dreams for creative problem-solving aligns with research showing that different sleep stages facilitate creativity in distinct ways. In Why We Sleep, Matthew Walker argues that REM sleep helps create novel connections between distantly related concepts that your brain wouldn’t link while awake. But other scientists propose that the memory consolidation that happens during non-REM sleep is the key to enabling these novel associations: During non-REM sleep, your brain abstracts general rules and patterns from information you’ve learned. Then, during REM sleep, your brain makes associations between these different abstracted patterns.

The alternation between these two sleep stages, both within a single night and across multiple nights, enables creative breakthroughs. It may also explain why these breakthroughs often feel like the recognition rather than invention of an idea. When REM sleep reorganizes how new memories connect to other information already in your brain, you’re not generating entirely new information, but recognizing hidden similarities between patterns you’ve already learned. The “breakthrough” comes when you wake up and suddenly see a connection that was invisible before because your brain hadn’t yet organized the information in a way that made the similarity obvious.

5. Influence What You Dream About

Beyond using the boundary states of sleep, you can influence dream content directly through pre-sleep suggestion. According to Jandial, simply stating an intention about what you want to dream about—aloud or mentally—nudges your dreams in that direction, particularly for problems with visual solutions. Focusing on a mental image of the desired subject while falling asleep also works because dreams are fundamentally visual. Your daytime mental life shapes your dreams as well: People who engage their imagination more during waking hours by daydreaming tend to have more vivid and creative dreams at night.

(Shortform note: How well does pre-sleep suggestion actually work? The scientific evidence is mixed. When researchers exposed people to images, sounds, or other sensory experiences before sleep, these elements appeared in their dreams anywhere from 0% to 80% of the time depending on the study, with most results falling between 3% and 43%. This huge variation partly reflects differences in how researchers conducted their studies, but it also reveals an important pattern: Personally meaningful, emotionally engaging content is far more likely to show up in your dreams than neutral material. Just telling yourself to dream about something, especially if it matters to you and you can visualize it, appears to be moderately effective.)

6. Gain Conscious Control Through Lucid Dreaming

The most advanced form of dream influence is lucid dreaming—becoming aware you’re dreaming while remaining asleep—which has been validated through experiments where participants signaled their awareness by moving their eyes in prearranged patterns while electrodes confirmed they remained asleep. Brain imaging shows that during lucid dreams, the Executive Network partially reactivates—specifically, the dorsolateral prefrontal cortex shows increased activity compared to ordinary dreaming. This gives you some awareness and potentially some control over the dream, though not complete conscious command. Scientists estimate that about one-third of people can learn to lucid dream with practice.

(Shortform note: Tibetan Buddhists have long practiced lucid dreaming in four distinct stages: First, recognize you’re dreaming. Second, overcome fear by recognizing that nothing in a dream can harm you. Third, change the dream. Finally, contemplate how all experience, both dreaming and waking, is constructed and impermanent. Tibetan monks report that experienced practitioners can maintain awareness even during deep, dreamless sleep. This sustained awareness is considered a path toward enlightenment, or “awakening,” which refers literally to waking up from the illusion that reality is fixed.)

Jandial explains there are many methods for inducing lucid dreams. One of the most accessible is reality testing, which involves regularly asking yourself during the day whether you’re awake or dreaming, then testing indicators that differ between states. Examine your hands (which dreams often distort), try pushing your hand through solid objects, or check digital displays, which show incorrect or morphing information in dreams. Building this habit when you’re awake may trigger reality tests within dreams, revealing you’re dreaming and sparking lucidity.

Jandial also recommends the MILD technique (Mnemonic Induction of Lucid Dreams). This involves waking after five hours of sleep—which typically catches you just before your longest REM period of the night—then, before returning to sleep, repeatedly telling yourself “The next time I’m dreaming, I will remember that I’m dreaming.” This works best if you fall back asleep within five minutes, which enables you to return directly to REM sleep while the intention remains fresh in your mind.

Can You Really Control Your Dreams Like in Inception?

These lucid dreaming techniques appear in Christopher Nolan’s 2010 film Inception, where specialists enter people’s dreams to extract secrets or plant ideas. The characters use reality checks—in the form of objects called “totems”—to determine whether they’re dreaming or awake. One character’s spinning top serves this function: It spins endlessly in dreams but eventually falls in reality. A strategy similar to the MILD technique also appears in the film: Characters discuss “remembering” that they’re dreaming and maintaining awareness across dream levels. They also time their entries into dreams, similar to how MILD practitioners wake after five hours to catch their longest REM period.

That said, lucid dreaming experts contend that Inception exaggerates what’s possible. While the film’s dream architects manipulate entire cityscapes at will, real lucid dreamers say their control of dream content remains difficult and partial. This limitation likely stems from how lucid dreaming works neurologically: The dorsolateral prefrontal cortex, while more active in lucid dreams than in other dreams, still only reactivates partially, not fully as it does when you’re awake. You gain enough consciousness to recognize you’re dreaming, but not complete control. This means lucid dreamers might manage to fly or change a scene, but maintaining stability and directing multiple elements often proves impossible.

7. Transform Your Nightmares

If you struggle with recurring nightmares, you can use your imagination to reshape them through Imagery Rehearsal Therapy. Jandial explains that this technique involves recalling the nightmare, rewriting the plot to make it pleasant instead of terrifying, and rehearsing your new version with vivid sensory details daily for several weeks. This works because nightmares are products of your imagination, and the same capacity that creates them can transform them. Research shows that this technique reduces both nightmare frequency and intensity. The success of Imagery Rehearsal Therapy reveals something fundamental: Since you create your own dreams, you can also reshape them through deliberate mental practice while awake.

(Shortform note: While Jandial presents Imagery Rehearsal Therapy as something you can practice on your own, the technique was developed to be delivered by trained therapists. That said, the self-directed approach Jandial describes can be effective for many people: The technique works by disrupting the script of recurring nightmares. When strong emotions interrupt the brain’s normal process of making novel associations during dreams, nightmares become repetitive rather than creative. By consciously rehearsing a new ending, you weaken this rigid pattern and signal to your brain that alternative outcomes are possible.)

8. Protect Your Dreams From Manipulation

While working with your own dreams offers benefits, Jandial warns that new technologies raise serious concerns about others manipulating your dreams without your consent. Researchers have developed algorithms that can identify dream images by matching brain activity patterns to reported content—essentially decoding what you’re dreaming based on brain scans. While current technology has limitations in speed and resolution, next-generation scanners will enable much more precise dream decoding. Along similar lines, companies are creating advertising campaigns designed to infiltrate dreams. For example, in 2021, the Molson Coors beer company created a campaign aimed at influencing Super Bowl viewers’ dreams.

Jandial recommends several protective steps: Sleep in environments without smart speakers. Keep phones away from your bed, as future user agreements for sleep-tracking devices might include clauses allowing companies to send quiet marketing messages during sleep. Avoid neurotechnologies with user agreements that grant companies control of your brain data. Support neural rights legislation—Chile became the first country in 2021 to amend its constitution to protect brain activity and information as a fundamental right. Be aware that the border between science fiction and current reality is narrower than you might think, and the technology to manipulate dreams already exists.

Dream Ads Work—But Not How You’d Think

Researchers have shown that a method of dream advertising called Targeted Dream Incubation (TDI) can influence dreams by pairing visual cues about a product with auditory cues played while people sleep. Though the success of this method has been modest so far, the vulnerability Jandial emphasizes is real. Sleep researchers warn that smart speakers—which 40 million Americans have in their bedrooms—could theoretically detect sleep stages and play sounds to influence your dreams without explicit consent. One researcher, Adam Haar of MIT, reports being contacted by three companies in two years, including Microsoft and two airlines, requesting help with dream incubation projects.

Research reveals that corporations are already influencing our dreams in another way: More than half of Americans aged 18-35 report having had dreams they believe were influenced by advertisements or included ad-like content. Many report seeing brands like Coca-Cola, Apple, or McDonald’s in their dreams, showing that the brands we’re constantly exposed to in our waking hours are also infiltrating our sleep. Scientists note that memories are “reactivated” during sleep, so the more people engage with brands daily—whether through smartphones or in public spaces dominated by fast-food chains and soda brands—the more likely it is that these brands will naturally appear in their dreams.

The science clearly shows dreams can be influenced through external stimuli, but whether companies can do this effectively and at scale remains an open question—one that may become moot if our constant brand exposure already does the work for them.