When I was drinking every night and dealing with a hangover every morning, I probably could have been described as less assertive.
But I don't think assertiveness would have been an accurate behavior to describe me. I think a more accurate description of my behavior would have been secretive.
I was really trying to hide my alcohol use, so I would try to blend in as much as possible and not call attention to myself. Some people may have labeled me non assertive, or introverted or shy. While I might have appeared that way to others, none of these labels would have been accurate. I was simply a drunk trying to hide my drinking.