Alcohol is a sedative, not a stimulant. The reason we can get rowdy is that it can sedate the parts of the brain that moderate our behaviour.
The quality of sleep when 'under the influence' is rather poor, yes. The parts of the brain that need to be exercised during sleep are sedated. You may often notice how, although you seem to have had a deep and dreamless sleep, you 'wake up tired,' if not hung-over.
After a while you can become alcohol-dependent, so that you need it to function. Trying to sleep when not 'under the influence' can be very difficult until you are finally free of dependence.
An insidious thing about alcohol-dependence is the way that it clouds judgement, so that recognition of this degradation in function produced by alcohol is absent. Too, if most of your friends are also alcohol-dependent, this can seem to be a normal state.
Every time this subject comes up here, just look at all the moaning about alcohol testing and the injustice of it all, serious thought given to just how much drink can be taken up to what point before flying, what sort of testing device one might use, etc., etc.
People in aviation realise that being caught with rather small blood-alcohol concentrations can be career death and yet they persist in drinking. What does that tell us?