The alcohol is not actually put in the medicines to knock you out, that is simply a side effect that many nighttime cough syrups enjoy. The alcohol is there because it is the safest solvent for drugs that do not mix well with water.

This is why pharmacists will recommend a tablet or lozenge for someone who does not want to drink alcohol. Alcoholics will be disappointed to find out that most cough syrup contains only 1 milliliter of pure alcohol per teaspoon as compared with the 15 milliliters found in a shot of bourbon.

(Y'all have that commercial, don't you?!)