Alcohol depresses the central nervous system, affects your judgment, and slows reaction time.
Alcohol decreases your attention span, which is risky even when you have only one task to perform. This especially complicates performing multiple tasks, such as steering your snowmobile while keeping track of others in the area.
Most people become slightly intoxicated after only one drink.
Over-the-counter drugs and prescription drugs, particularly tranquilizers and barbiturates, have effects similar to alcohol.
Marijuana slows your reflexes and reduces night vision.
Cocaine and amphetamines may increase your concentration temporarily but cause fatigue as the drug wears off. They also give you an exaggerated feeling of well-being, which affects judgment and leads to reckless behavior.