Not watched it, but...sometimes when I'm sad/pain I go a bit weird after/during the downer and can go laughing smiling like a complete nutter. Sometimes I have to hide it because it is often inappropriate at that time. Lot of people have this. It's just a way your mind has of protecting you from the sadness/grief/whatever.

Of course this may or may not be what this is, but I just thought I'd put this out there.