Alcohol depresses inhibitions, wakes you up and for some people makes them hungover. While I occasionally drink bourbon, I more often drink dark rum, and my favorite is Scot's whisky. I've been drinking regularly for more than 50 years, and have two hangovers in my life. I have come to believe that many have an allergy to alcohol, but your friend's experience makes me wonder if it is an allergy to certain components in spirits. Buy a small bottle of decent vodka, mix it with cranberry and see how you feel the next morning. Or even better, drink martinis with just a breath of vermouth. Either way, if you don't have morning after effects, he's on to something.