FRIDAY, Dec. 31 (HealthDay News) -- Two to three times more people die in alcohol-related crashes on U.S. roads during Christmas and New Year's than over comparable periods of time during the rest of the year, says the U.S. National Institute on Alcohol Abuse and Alcoholism.

The agency also noted that 40 percent of traffic deaths during these holidays involve an impaired driver, compared to 28 percent for the rest of the month of December.

While most people are aware of the dangers of drinking and driving, they may underestimate the effects of alcohol and make poor decisions that could lead to tragedy.

Long before a person who is consuming alcohol shows physical signs of intoxication, their driving-related skills and decision-making abilities are already diminished, according to the NIAAA. Continued alcohol consumption leads to a decrease in reaction time, poor behavior control or aggression, loss of balance and drowsiness.

Many people mistakenly believe that they're fine to drive if they stop drinking and have a cup of coffee. But alcohol continues to affect the brain and body long after you stop drinking, impairing judgment and coordination for hours, the experts warn.

Even the next day, alcohol remaining in your body or hangover-related headache and disorientation can cause sluggishness and impair a person's ability to drive safely, the NIAAA says.

If you plan to drink any alcohol, make plans to get home safely, such as having a designated driver, the agency advises.

More information

The U.S. Centers for Disease Control and Prevention has more about alcohol-impaired driving.