That eerie sense that the world around you isn’t quite real, that everything feels slightly artificial or scripted, comes from a mix of psychological, neurological, and even philosophical factors. For some people it’s a fleeting oddity after a stressful day. For others it’s a persistent fog that colors everyday experience. Understanding where the feeling comes from can make it far less unsettling.
Your Brain Has a Reality-Monitoring System
Your brain doesn’t passively absorb the world. It actively sorts every piece of incoming information into categories: did this come from outside me, or did I generate it internally? This process, called reality monitoring, is how you distinguish a memory of something that actually happened from something you only imagined. It’s run largely by a region in the front of the brain (the anterior medial prefrontal cortex) that adjusts its activity depending on whether sensory input is self-generated or coming from the environment. When this system works smoothly, the world feels solid and continuous. When it’s disrupted, even slightly, the boundary between “out there” and “in my head” starts to blur.
Other brain areas contribute too. A region in the parietal lobe helps distinguish self from non-self. When that area becomes overactive in response to self-generated signals, people can experience the feeling that their own thoughts or actions belong to someone else, or that their surroundings have a stage-set quality. The system is robust, but it’s not immune to stress, fatigue, or neurochemical shifts. Even healthy brains can temporarily glitch in this department.
Derealization: When “Simulation” Feeling Has a Name
The clinical term for the persistent sense that the world around you isn’t real is derealization. It’s one half of depersonalization/derealization disorder, a dissociative condition in which people feel detached from their surroundings, their body, or both. The experience maps remarkably well onto what people describe when they say life feels like a simulation.
People with derealization report feeling as though they’re living in a movie or a dream. Surroundings can appear flat, colorless, or two-dimensional, as if depth has been stripped away. Objects look blurry or, paradoxically, unnaturally sharp. Sounds seem too loud or too soft. Time warps: recent events can feel like they happened years ago, or hours can seem to pass in minutes. There’s often a sense of being separated from the world by a glass wall or a veil, able to see everything but unable to feel connected to any of it.
One important detail: people with derealization know it’s not actually real. Their reality testing remains intact. They’re aware the world hasn’t literally changed. That gap between what they know intellectually and what they feel emotionally is part of what makes the experience so disorienting. Derealization episodes can be triggered by severe stress, anxiety, sleep deprivation, trauma, or sometimes by nothing identifiable at all. Transient episodes are common in the general population, especially during periods of high anxiety or exhaustion. For most people, these pass on their own. The disorder is only diagnosed when the experiences are persistent or recurrent enough to significantly impair daily life.
Pattern Recognition and “Glitches in the Matrix”
Beyond derealization, there’s a cognitive reason the simulation idea feels so compelling: your brain is a pattern-detection machine, and it’s not always accurate. At any given moment, you’re taking in far more sensory information than you consciously process. Your brain filters most of it out and only flags what seems relevant. When something suddenly becomes important to you, like the concept of simulation theory, you start noticing “evidence” for it everywhere. A strange coincidence, a moment of déjà vu, a weirdly timed event. This is the frequency illusion, sometimes called the Baader-Meinhof phenomenon.
The frequency illusion works because things that are recently important to you receive more attentional processing and are more likely to reach conscious awareness. You aren’t usually aware of why you notice what you do. So when you start seeing eerie coincidences pile up, it genuinely feels like the universe is glitching rather than your attention selectively highlighting patterns that were always there. The human tendency to find meaningful patterns in random noise, called apophenia, amplifies this further. Combine it with a cultural moment saturated in simulation language (from movies, memes, tech culture) and the framework becomes self-reinforcing.
The Philosophical Argument
The feeling also persists because there’s a serious philosophical case behind it. In 2003, philosopher Nick Bostrom at Oxford proposed what’s now known as the simulation argument. It doesn’t claim we definitely live in a simulation. Instead, it argues that one of three propositions must be true: nearly all civilizations at our stage of development go extinct before developing the computing power to simulate conscious beings; nearly all civilizations that do reach that level lose interest in running such simulations; or the vast majority of beings with experiences like ours are, in fact, simulated.
The logic is straightforward. If a civilization could simulate billions of conscious minds, and chose to do so, the number of simulated beings would vastly outnumber “real” ones. Statistically, any given conscious being would be far more likely to be simulated than biological. The argument doesn’t prove anything. It simply shows that dismissing the possibility requires you to commit to one of the first two propositions, which carry their own unsettling implications about humanity’s future or motivations.
What Physics Actually Says
Some physicists have explored whether the physical world itself shows signs of being computed. The reasoning goes like this: if our universe runs on a computer, that computer has finite resources. At some very small scale, space and time would have to become discrete, pixelated, rather than infinitely smooth. There might be tiny inconsistencies where the “code” breaks down, similar to how collision detection errors in video games cause objects to clip through walls or get stuck on invisible obstacles.
Another line of thinking considers hardware errors. Real computers are affected by their physical environments. Cosmic radiation, for instance, can flip individual bits in a computer’s memory. If our universe were simulated, similar errors could introduce faint, unexplainable noise into physical processes, particularly at quantum scales. Some researchers have pointed out that if physicists discovered persistent, unexplainable noise in quantum experiments that couldn’t be attributed to their equipment or any known physical process, it would at minimum raise questions about whether the “hardware” running reality is imperfect.
But this cuts both ways. The argument only works if physics does become discrete at some fundamental scale. If there’s no bottom resolution, if space and time are infinitely divisible, then the information density of our universe would be infinite, and no finite computer could simulate it. Current physics hasn’t settled this question. The simulation idea remains unfalsifiable with existing tools, which is exactly why it stays in the territory of philosophy rather than science.
Why Stress and Anxiety Make It Worse
If you’ve noticed the simulation feeling intensifies during stressful periods, that’s not a coincidence. Derealization is closely linked to the body’s stress response. When your nervous system is overwhelmed, dissociation acts as a kind of circuit breaker, dulling your emotional connection to what’s happening around you. The world doesn’t change, but your experience of it gets muffled. Colors seem flatter, people seem more distant, time feels wrong. Your brain is essentially dampening the signal to protect you from emotional overload.
Sleep deprivation has a similar effect. After enough hours without rest, reality monitoring degrades. You become worse at distinguishing internal mental activity from external input. The world takes on a hazy, dreamlike quality that maps directly onto what people describe as the simulation feeling. Chronic anxiety keeps this system in a low-grade disrupted state, which is why some people experience the unreality sensation for weeks or months rather than minutes.
Grounding Techniques That Help
If the feeling is distressing rather than just philosophically interesting, sensory grounding can interrupt the dissociative cycle. The most widely used approach is the 5-4-3-2-1 technique, which works by flooding your brain with concrete sensory data and forcing your attention back into the physical world. Start with slow, deep breaths, then identify five things you can see, four you can physically touch, three you can hear, two you can smell, and one you can taste.
The exercise works because derealization thrives on abstraction. When your brain is looping on meta-level questions about whether reality is real, you’re operating entirely in the prefrontal cortex, disconnected from sensory input. Deliberately engaging all five senses pulls processing back toward the parts of the brain that anchor you in the present moment. The smell of soap, the texture of your sleeve, the hum of a refrigerator: these are hard for your brain to file as “unreal” when you’re paying close attention to them. The effect is temporary, but repeating the technique during episodes can gradually reduce their intensity and frequency over time.