The Impact of Alcohol on Your Body


Every drink taken effects the functioning of the brain in some way – especially the ability to perform complex tasks. The degree of impairment depends on the complexity of the task involved as well as the Blood Alcohol Content (BAC). More complex tasks are effected before less complex tasks. Alcohol-induced impairment rises as BAC increases and decreases as alcohol is eliminated from the body. There is not an absolute BAC threshold below which there is no impairment. Some driving skills are impaired at 0.01% to 0.02% BAC.

A driver’s ability to divide attention between two or more sources of visual information can be impaired by BACs of 0.02% or lower. However, impairment occurs consistently in eye movements, glare resistance, visual perception, reaction time, certain types of steering tasks, information processing, and other aspects of psychomotor performance with BACs of 0.05%.

Control of eye movements is very vulnerable to alcohol. In driving, the eyes must focus briefly on objects and track them as they (and the vehicle) move. At a BAC of 0.03%, alcohol impairs the eye’s ability to rapidly tract a moving object. Steering is a complex psychomotor task in which alcohol’s effect on control of the eyes impacts on eye-to-hand reaction time. Impairment of steering ability begins a low as 0.035% BAC.

Alcohol impairs nearly every aspect of information processing by the brain. Alcohol-impaired drivers require more time to read a street sign or to respond to traffic signals than unimpaired drivers. As a result, they tend to look at fewer sources of visual information.

The most sensitive aspect of driving performance is the division of attention among component skills. Drivers must keep their vehicles in the proper lane and direction (a tracking task) while monitoring the environment for safety information such as other vehicles, traffic signals, or pedestrians. Alcohol-impaired drivers tend to concentrate on steering with less attention to safety information. Divided attention deficiencies start with BACs as low as 0.02%.

There are many myths surrounding the use of alcohol in regards to driving. Those who say they can drive better after a drink or two are fooling themselves and putting themselves and others at risk. Alcohol affects the many skills used automatically and unconsciously every time we drive. The onset of impairment may be so subtle that the driver is not aware of it – or if they are, they misjudge its effects because alcohol decreases the driver’s ability to make critical judgments. Even one drink degrades one’s driving ability to some degree. Do not, ever, drink alcoholic beverages and drive.