"she was not her self/ he was not himself"

IT has been said about me, as a matter of fact. I think what people mean when they say this, is that we are acting differently than we normally do. For example, if someone is upset, they will react in a manner that they may not react in if they were calm and contented. Sometimes people also say this when someone is intoxicated. I however beileve it is not so much that they "aren't themselves" but rather "under the influence" of a substance which is causing them to interact differently with situations. In a way, we are always "ourselves". It is the variables around us which determine how we react or act in a situation.