Drinking darker-colored liquor like whiskey or bourbon is more likely to leave you with a hangover the next day than downing vodka or other clear liquors, researchers say.

However, no matter what you drink your cognitive function is likely to be impaired even after you sober up, LiveScience reported Dec. 18.

Dark-colored liquors contain more congeners — toxic substances caused by fermentation — than light-colored ones. “While the alcohol alone is enough to make many people feel sick the next day, these toxic natural substances can add to the ill effects as our body reacts to them,” said study author Damaris Rohsenow of the Center for Alcohol and Addiction Studies at Brown University.

Researchers found that drinking alcohol made study subjects feel worse the next day than those who received a placebo, and that those who were given bourbon to drink felt more hung over than those who drank vodka. Bourbon and vodka drinkers performed equally poorly on cognitive tests, the study showed.

The research was published online in the journal Alcoholism: Clinical & Experimental Research.