Alcohol is classified as a central nervous system (CNS) depressant, slowing down brain activity and nerve communication. The feeling of “being drunk” is a progression of mental and physical changes that directly correlate with the Blood Alcohol Concentration (BAC). As the body absorbs alcohol faster than the liver can metabolize it, the BAC rises, and the subjective experience shifts dramatically, varying based on individual factors like weight, gender, and tolerance.
Early Effects: Relaxation and Sociability
At the lowest levels of intoxication (BAC between 0.02% and 0.05%), the experience is characterized by mild stimulation. Drinkers report a feeling of warmth, slight giddiness, and a general sense of well-being, often called a “buzz.” This mild euphoria is accompanied by a perceived increase in confidence and talkativeness, as the brain exhibits reduced inhibitions.
Physiologically, this initial feeling stems from alcohol’s interaction with the brain’s neurotransmitter systems. Alcohol enhances the activity of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter, which slows down nerve activity. This boost in transmission leads to a temporary reduction in anxiety and relaxation. Even at this stage, mild impairments in speech, balance, and attention may already be measurable.
Impaired Perception and Coordination
As consumption continues and the BAC rises into the moderate range (0.06% to 0.15%), the depressant effects become more pronounced. The feeling of easy confidence overrides actual competence, leading to impaired judgment and decision-making. Physical sensations of clumsiness emerge as alcohol interferes with the cerebellum, the brain region controlling coordination and balance.
This manifests as a loss of fine motor control, causing difficulty with precision tasks and often resulting in slurred speech. Vision becomes distorted, sometimes leading to difficulty focusing or double vision, which contributes to the feeling of being off-balance. The disorienting “spinning” sensation, known as vertigo, results from alcohol changing the density of fluid in the inner ear’s balance mechanisms. Reaction time is delayed, and memory may become moderately impaired.
The Danger Zone: Confusion and Stupor
When the BAC reaches severe levels (typically above 0.20%), the experience shifts from impaired functioning to intense physical and cognitive shutdown. The feeling of giddiness disappears, replaced by disorientation, confusion, and sometimes dysphoria (a state of unease or dissatisfaction). At this point, the ability to track conversations or form new memories is severely compromised, leading to episodes known as blackouts or brownouts.
Physical symptoms transition into dangerous signs, including uncontrollable nausea and vomiting, as alcohol irritates the stomach lining. The body loses the ability to regulate functions, leading toward stupor, where the person is barely conscious and difficult to rouse. At extremely high levels (above 0.31%), vital functions like breathing and heart rate are suppressed, putting the individual at risk of respiratory arrest, coma, and death.
The Post-Intoxication Experience
The feelings of “being drunk” give way to the post-intoxication experience, known as a hangover, which begins when the BAC returns to or nears zero. This state is the body’s reaction to toxic byproducts of alcohol metabolism, such as acetaldehyde, and severe dehydration. The primary physical sensation is often a throbbing headache, caused partly by dehydration and the widening of blood vessels.
Extreme thirst and a dry mouth are common due to alcohol’s diuretic effect, which causes the body to excrete more fluid. The stomach feels unsettled, leading to nausea, stomach pain, or general malaise. Other unpleasant sensations include fatigue, muscle aches, and a heightened sensitivity to light and sound. This state is often accompanied by mental symptoms, such as anxiety, irritability, and difficulty concentrating.