Getting high is the result of substances (or sometimes intense experiences) flooding your brain’s reward circuitry with more stimulation than it was designed to handle on its own. The specific feeling varies wildly depending on what’s doing the flooding, but the common thread is a hijacking of systems your brain already uses to motivate you, process pleasure, and filter reality. Here’s how that works across different substances and situations.
The Brain’s Built-In Reward System
Your brain has a deep motivational circuit that evolved to push you toward food, sex, social connection, and exploration. When this system activates, neurons in the midbrain release dopamine into areas that generate what researchers call a “seeking” disposition: a state of enthusiastic excitement, desire, and euphoria tied to pursuing something rewarding. This isn’t the calm satisfaction of eating a meal. It’s the charged-up anticipation before you take the first bite.
Drugs of abuse essentially force this system into overdrive. Psychostimulants provide what one research group at Bowling Green State University described as “an artificial way to stimulate the emergence of the SEEKING disposition,” producing euphoria and exhilaration that normally only arise during genuine reward pursuit. The feeling is powerful precisely because it’s activating circuits that evolved over millions of years to keep you alive. Your brain treats the signal as profoundly important, even though nothing meaningful is actually happening.
How Stimulants Create a Rush
Cocaine and amphetamines both increase dopamine levels in the gaps between neurons, but they do it differently. Cocaine works like a plug in a drain: it blocks the recycling mechanism that normally pulls dopamine back into the neuron that released it. Dopamine piles up in the gap, stimulating the receiving neuron far longer and harder than normal. Cocaine doesn’t make your brain produce extra dopamine. It just prevents cleanup.
Amphetamines go a step further. They block reuptake the same way cocaine does, but they also force neurons to release more dopamine into the gap in the first place. This double action is why amphetamines tend to produce a longer, more intense high. Methylphenidate (the active ingredient in Ritalin) sits somewhere in between: it blocks reuptake like cocaine but doesn’t significantly boost the initial release.
The physical signs of stimulant use reflect this dopamine surge. Heart rate climbs, pupils dilate, skin conductance increases. These changes track together closely. Studies using real-time physiological monitoring show that pupil diameter correlates with heart rate and sweat response, all driven by the same spike in sympathetic nervous system activity that accompanies the rush.
How Cannabis Produces Its High
Cannabis works through an entirely different mechanism. Your brain naturally produces its own cannabis-like molecules called endocannabinoids, which fine-tune communication between neurons. THC, the main psychoactive compound in marijuana, mimics one of these molecules (anandamide) and binds to the same receptors, called CB1 receptors, scattered throughout the brain.
When THC activates CB1 receptors, it triggers a chain of events inside the neuron. The cell reduces its production of a key signaling molecule (cyclic AMP), which changes how ion channels behave. The result is that certain nerve terminals become less responsive to incoming signals. This blunting effect is why cannabis can dull pain, slow reaction time, distort time perception, and produce a dreamy, relaxed state. The high comes not from revving up a system, as stimulants do, but from selectively turning down the volume on neural communication in regions involved in memory, coordination, and sensory processing.
THC also acts as a partial activator of pathways that release calcium inside cells, which affects how neurons signal to one another. The net effect is a complex mix: some circuits get quieter while others become unusually active, producing the characteristic blend of relaxation, heightened sensory experience, and altered thinking.
How Psychedelics Alter Perception
Classic psychedelics like psilocybin (from magic mushrooms) and LSD produce their effects primarily by activating serotonin receptors, specifically the 5-HT2A type. Psilocybin itself is inactive. Your body converts it into psilocin, which then binds to serotonin receptors. LSD binds to both serotonin and dopamine receptors, which partly explains why its effects feel distinct from a mushroom trip.
What makes psychedelics unique is their impact on a brain network called the default mode network (DMN). This is the collection of brain regions most active when you’re thinking about yourself, ruminating, or daydreaming. It’s essentially the neural basis of your sense of “I.” Psychedelics consistently disrupt communication within this network while simultaneously increasing connectivity between brain regions that don’t normally talk to each other. One study found that out of nearly 36,000 possible neural connections analyzed, 695 were significantly different from baseline after psychedelic administration.
This rewiring is what produces the hallmark effects: visual distortions, a feeling that boundaries between yourself and the world are dissolving, and a sense of profound meaning or interconnectedness. The weakening of the DMN correlates directly with what users describe as “ego dissolution,” a temporary loss of the normal sense of self. For some people this feels transcendent. For others it’s terrifying. The same mechanism drives both experiences.
Getting High Without Drugs
Your body can produce its own version of a high. The “runner’s high,” that wave of calm euphoria some people feel during sustained aerobic exercise, was long attributed to endorphins. That explanation turns out to be incomplete at best. Running does increase blood levels of both endorphins and anandamide (the same molecule THC mimics), but endorphins are too large to cross the blood-brain barrier. They circulate in your blood but can’t reach the brain regions that generate euphoria.
Anandamide, on the other hand, is fat-soluble and crosses into the brain easily. Research from the University of Heidelberg demonstrated that the anxiety-reducing and pain-relieving effects of running in mice depended entirely on intact cannabinoid receptors. When those receptors were blocked, the runner’s high disappeared. Pain reduction specifically required CB1 and CB2 receptors in the body’s periphery, while the anxiety relief depended on CB1 receptors in the forebrain. In other words, your body’s own cannabis system, not its opioid system, appears to be the primary driver of exercise-induced euphoria.
Why the High Fades With Repeated Use
One of the most consistent features of any high is that it gets harder to achieve with repeated exposure. This is tolerance, and it happens at the cellular level through a process called receptor downregulation. When a receptor is bombarded with stimulation over and over, the cell physically pulls it inside through a process called endocytosis. The receptor gets swallowed into the cell’s interior, where it’s either broken down and destroyed or stored for potential recycling back to the surface later.
Fewer receptors on the surface means less response to the same dose. Your brain is essentially turning down its own sensitivity to protect itself from overstimulation. This is why people who use substances regularly need progressively larger amounts to feel the same effect. The high hasn’t changed. The brain’s ability to receive the signal has been deliberately reduced.
This same process contributes to the shift from casual use to compulsive use. As the reward system becomes less sensitive, everyday pleasures (a good meal, a conversation with a friend) produce even less of a dopamine response than they did before. The gap between how a substance makes you feel and how everything else makes you feel widens, which can drive a cycle of escalating use. Clinically, substance use disorder is diagnosed on a spectrum: meeting 2 to 3 of 11 behavioral criteria qualifies as mild, 4 to 5 as moderate, and 6 or more as severe. Those criteria include things like using more than intended, unsuccessful attempts to cut back, craving, and continuing use despite clear harm to relationships or health.
Why Different Highs Feel So Different
The reason a cocaine high feels nothing like a cannabis high, which feels nothing like a psychedelic trip, comes down to which neurotransmitter systems are being affected and where in the brain the action is concentrated. Stimulants hammer the dopamine system, producing a focused, energized, confident euphoria. Cannabis dampens neural signaling broadly, creating relaxation and sensory distortion. Psychedelics scramble the brain’s self-referential networks through serotonin, dissolving normal patterns of perception and identity.
Each substance also carries a different physical signature. Stimulants raise heart rate, dilate pupils, and increase sweating, all reflections of sympathetic nervous system activation. Cannabis often lowers blood pressure and increases appetite by acting on receptors in the hypothalamus. Psychedelics can produce nausea, changes in body temperature, and pupil dilation, but their most dramatic effects are perceptual rather than cardiovascular. These physical differences are clues to which brain systems are being activated, and they’re part of why “being high” is not one experience but many, all unified by the common thread of a brain pushed temporarily beyond its normal operating range.