Alcohol can have a different effects on different people.
Generally speaking alcohol is an hypoglycemic substance, in other words it tends to lower blood sugar levels. This is why moderate alcohol consumption can be beneficial to diabetic people, but can be disastrous to hypoglycemic people.
Hypoglycemic people, thus people with unstable blood sugar levels, tend to have adverse reactions to alcohol. Some people experience a change in personality when they drink alcohol, and can even become violent or aggressive under the influence of alcohol. They may act "out of character".
This happens when alcohol causes a hypoglycemic dip and their brains become energy starved.
Some people seem to enjoy themselves under the influence of alcohol. This may be because alcohol is also an antidote to adrenaline, the worry hormone. They may feel strangely confident in the presence of people and this explains why alcohol may be described as a "socializer".
However being a hypoglycemic substance it can cause low blood sugar levels and this will kick in adrenaline (to raise the BS levels) and so some people have aggravated anxiety attacks. When I was sick, I loved alcohol, because of its tranquilizing effects on my anxiety attacks, but unfortunately it caused me many a sleepless nights. I know others would fall asleep under the influence of alcohol. We are all different.