People who have a pattern of heavy drinking showed less impairment than light drinkers after drinking similar amounts of alcohol — yet this difference depends largely on how much time has elapsed after drinking and may only be evident at moderate intoxication. A study published in Alcohol: Clinical and Experimental Research found that people who exceed drinking an amount of alcohol that is typical for them showed substantial impairment. And, when heavy drinkers and lighter drinkers were similarly impaired, the heavy drinkers perceived themselves to be less impaired, which may lead to risky decisions.