Drinking whisky will result in a worse hangover than drinking vodka, according to U.S. researchers, although vodka has negative effects, too. It might be because of molecules called “congeners,” of which there are more in whisky than in vodka; congeners contain small amounts of chemicals like acetone, acetaldehyde and tannins, according to researchers at Brown University. In the study, 95 volunteers, all healthy alcohol users, were given enough booze to put them one-third over the legal driving limit. On the third night, they were given a “placebo” drink with no alcohol. The day after each session, the subjects were asked how they felt, and were tested on how well they could concentrate. Volunteers who drank whisky reported more symptoms like headache, nausea, thirst and fatigue, than those who drank vodka. But the overall performance at the concentration task was about the same between two groups. Disrupted sleep was also about the same in both groups.