Alcohol depresses the central nervous system, impairing chess performance.
Nevertheless, I've been able to reverse a losing streak at blitz by drinking a glass of bourbon, or a couple of pints of Guinness. My thoughts are not more clear, but my inhibitions are reduced, and sometimes that lets me play fast and loose. Also, when buzzed, I don't care so much, and that can help in blitz because I'm playing to enjoy.
When I make moves at RHP on such evenings, they are bad moves more often than not.
The Bourbon Society