I have found that personally, my SA ceases to exist once i've had a few drinks. Completely disappears. hell, once i've had a few drinks i'm walking up to random girls in clubs and getting with them, something that I doubt I could ever do sober.
However, the more drinks I have (to make me feel more confident), the more depressed and lonely I feel if i'm alone in my bedroom when I get home, and boy, i've had some borderline suicidal moments in the past.
In fact, the only times i've cried in my entire life have been when i've been drinking and am alone in my bed.
So, to conclude, alcohol in my experience has it's good and bad points.