It's not under any influence of alcohol! It's just a gesture. Eyes are half closed with creases on the forehead and some tension in the muscles around the eyes. Such expressions are made when you doubt something or find something suspicious.
I'm trying a lot but not finding even a single image! Why? Because I don't know what it is called!
Best Answer
In detective stories, you'll often read the expression
More often than not, when someone is thinking deeply, English speakers will focus on the creases in the forehead, which is called a frown