Alcohol blunts alertness and reduces motor concentration, harms your reaction time, and affects your vision. In addition, it alters your depth perception which makes it difficult to tell whether other vehicles, pedestrians or objects are close or far away. It can also affect your judgement, making some drivers overconfident, where they may not recognize their driving skills have been reduced. Their driving also becomes reckless and careless, involving speeding, driving off the road, and too often, crashing. Since alcohol is also classified as a depressent drug, it slows down your body and your brain.
Police officers are trained to recognize signs of driver impairment. Examples can include erratic driving, slurred speech, bloodshot eyes and unsteady balance. If a police officer has reasonable suspicion to believe a driver may be under the influence, he or she can require the driver to perform certain coordination tests, submit to an evaluation, or provide samples for analysis.
Drugs can also alter even the most experienced drivers' skills. Other depressent drugs such as sedatives and painkillers also affect a person's ability to drive in a similar way to alcohol. Stimulants such as coffee, amphetamines, and cocaine increase alertness, but this does not mean they improve driving skills. This feeling of alterness can be quickly worn off. At this point the only remedy is to get off