To first explain the relation of alcohol and it's effects on dreams, I would like to postulate how alcohol is aborsed into the nervous system. (Skipping the digestion...)

Ethanol, the active ingredient in alcoholic beverages, reduces anxiety, tension and inhibitions. In low doses it may act as a stimulant, whereas at higher doses, it acts as a depressant. In both cases, it significantly alters mood and behavior. It can also cause heat loss and dehydration. Without delving into the reasons why ethanol does these specific things, let's continue with the effects upon the nervous system.

The drug, which is easily absorbed into the bloodstream and the brain, affects several neurotransmitter systems. For example, alcohol's interaction with the gamma-amino butryic acid (GABA) receptor can calm anxiety, impair muslce control and delay reaction time because of the inhibitory effects and responsibility of GABA. At higher doses, alcohol also decreases the function of n-methyl-d-aspartate (NMDA) receptors that recognize the neurotransmitter glutamate. This interaction can cloud thinking and eventually lead to a coma.

(Note: Researchers at the Society of Neuroscience in Washington are developing treatments, which interfere with molecules, such as the opioid peptides, and trigger alcohol's positive reinforcing effects. One such drug, naltrexone, recently has been approved for treating alcoholism. Imagine the extents of these drugs..)

So, now with that declared, the essential of effect of alcohol upon dreaming itself is........ nothing. Ethanol and the inihibition of GABA only helps the process of falling asleep. If anything, ethanol will most likely make it harder to dream. The closest influence alcohol has upon actual dreaming is that it will assist in the inhibition of the consciousness and allow the subconscious to truly project is sole thoughts without any interruption whatsoever. Ethanol will also decrease acetylcholine and monoamine activity (with GABA) thus making it extremely difficult to become lucid, if not impossible.

Hope I have been enlightening.