Defining the Drinking and Driving Problem.

Highway deaths have been rising steadily until nearly 60,000 Americans are now being killed yearly.  It has been show that alcohol is involved in half of the highway fatalities.  Drivers with chronic drinking problems are responsible for about two thirds of the alcohol related deaths.  Young drivers and social drinkers with high blood-alcohol levels at the time of the accident cause the remaining one-third.  These figures do not include 5000,000 people injured annually and many disabled, nor do they cover the immense cost in property damage,  expenses wage losses and higher insurance costs.

The Physiological Effects of Alcohol.

You must exercise mental and physical skills in tandem to safely control your vehicle.  Alcohol slows the nervous system and dulls these skills to a great extent.  Your vision, reflexes, and coordination, as well as your breathing and heartbeat, are all affected by alcohol.  This makes preforming multiple tasks at once, such as braking and steering extremely difficult.

Vision

Alcohol relaxes the fine, delicate muscles the move the eyes and allow them to focus.  This drduces your ability to scan effectively and blurs your vision.  In some people, alcohol causes double vision, an uncontrollable rapid vibration of the eye that makes it almost impossible to see at all.
    Alcohol further impairs your awareness of the driving environment by distorting your depth perception, narrowing the scope of your peripheral vision, and impairing you night vision. Your vision need only be mildly impaired by alcohol to have trouble identifying hazards. You need depth preception to judge the speed of on coming vehicles, your stopping distance, and your distance from other vehicles, objects and people around you.  For example if you have been drinking you may perceive a red light to be father away and have to slam on your brakes at the last second to avoid entering an intersection.  Drivers under the  influence of alcohol also tend to stare at one spot and forget to scan constantly with their eyes. The combination of blurred peripheral vision  and fixation on narrow field ahead can result in tunnel vision, a 70% reduction your field of vision.
    You need more light to see dimly lit objects.  Alcohol impairs your night vision as much as 25% by reducing the time it takes for the pupils of your eyes to respond to the changes in light levels.  Because of this your eyes will take to adjust, you may be blinded more easily by on comming headlights and continued blurred vision long after the on comming car has passed.

Physical Reflexes and Coordination

As more alcohol enters the bloodstream, the more portions of the brain that control physical reflexes and coordination become depressed. This obviously has a severe effect on your abilities to operate your car.  Your reaction time gets longer the more you drink.  The brain works less efficiently, and instruction the muscles are delayed.

How Alcohol Affects Judgment.

When you drink, your ability reason and make sound judgments is decreased. Your ability to concentrate and remember is drastically reduced and it takes longer to process information.  A alcohol impaired driver may be more incline to run a yellow light or attempt to pass without sufficient room.   Often a person drinking alcohol will get a sense of well-being and will experience  an increase in confidence an lose their inhibitions.  Inhibitions  are elements of your personality that stop you from behaving without regard to possible consequences.