Alcohol, chemically known as ethanol, is a psychoactive substance and a central nervous system depressant that profoundly alters mental and physical function. People commonly use subjective terms like “buzzed” and “drunk” to describe varying levels of intoxication. To understand the difference between these states, it is necessary to examine the objective biological and chemical changes alcohol causes in the body. The spectrum of alcohol’s impact, from mild euphoria to severe motor and cognitive failure, is precisely defined by its concentration in the bloodstream.
How Alcohol Affects the Central Nervous System
After consumption, alcohol is quickly absorbed primarily through the small intestine and stomach lining before entering the bloodstream and traveling to the brain. Once ethanol crosses the blood-brain barrier, it begins to act as a depressant, slowing down neural activity and communication. This effect is largely due to its interaction with two major neurotransmitters: Gamma-aminobutyric acid (GABA) and glutamate.
Alcohol enhances the effects of GABA, which is the primary inhibitory neurotransmitter in the brain, effectively applying the brakes to the central nervous system. Simultaneously, alcohol suppresses the activity of glutamate, the brain’s main excitatory neurotransmitter, further decreasing overall brain activity. This dual action creates an imbalance in brain chemistry, leading to the characteristic feelings of relaxation and reduced inhibition.
The Blood Alcohol Concentration Scale
The standard, objective metric for measuring a person’s level of intoxication is Blood Alcohol Concentration (BAC), expressed as a percentage of alcohol in the blood. BAC directly correlates with the severity of physical and mental impairment, providing a scientific basis for defining the subjective states of intoxication. It is calculated as grams of alcohol per 100 milliliters of blood.
The state commonly described as “buzzed” aligns with the mild impairment stage, typically occurring at BACs between 0.01% and 0.05%. Within this range, individuals may experience slight changes in mood, such as relaxation, a sensation of warmth, or mild euphoria, alongside minor impairment in judgment. For many, a BAC in the 0.05% range is associated with lowered inhibitions and a reduced capacity for complex reasoning and memory.
The state of being “drunk” is objectively defined by the significantly impaired stage, which begins around a BAC of 0.08% and above. At this level, the effects progress to noticeable slurred speech, impaired balance, and a significant loss of motor coordination and reaction time. Moving to higher BACs, such as 0.11% to 0.15%, results in gross motor impairment and severely impaired judgment and perception, marking a clear progression from the initial “buzzed” feeling.
Functional Differences in Impairment
The difference between being “buzzed” and “drunk” is a contrast between slight functional changes and dangerous cognitive and motor failure. A BAC in the “buzzed” range (0.01%–0.05%) results in subtly slowed reaction times and slight coordination loss, which may not be immediately obvious to an observer. Although this level of impairment is measurable and reduces the ability to multitask effectively, it is often primarily characterized by psychological effects like euphoria and disinhibition.
In contrast, a BAC of 0.08% or higher, which defines the “drunk” state, involves a dangerous level of functional failure that extends far beyond minor changes. This level of intoxication is the legal threshold for driving impairment (DUI/DWI) in most of the United States. At a BAC of 0.08%, a person’s muscle coordination, judgment, and ability to detect danger are significantly reduced, leading to a much higher risk profile for accidents and injuries.