system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some people's personalities completely change when they are drunk?

I am a very easy going guy but when I got blackout drunk I had the tendency to become an overly aggressive jackass. I have since quit drinking but the question remains; why do some people become different when they are drunk?
gpt
Alcohol basically has an anti anxiety effect. A person's level of anxiety is a huge part of their personality. Some people (I am one of them to an extent) are extra nice because they feel if they are even a bit rude, people would stop talking to them. Now, when one gets drunk, this filter disappears, and they lose the need to try to impress people and be honest about what they feel. 

For someone who has a higher anxiety level, this sudden loss of anxiety can be a new and unnatural state and causes a "too free" or aggressive behaviour. While someone who doesn't have huge anxiety levels in regular life will be more comfortable in this state.

Simply put it depends how much anxiety you have in your sober state.