OK, I just started my first (temp) job here, and it seems that the people here go out drinking in the evening at least a few times during the week, if not every night. I'm used to people getting together after work on a Friday and going out for some drinks, but not during the week, when they have full-time jobs, unless it was to celebrate a special occasion, like a birthday.
People also talk openly at work about being hung over, the same way I would talk about the pollen count bothering my allergies. I can't imagine anyone at work in the US admitting to being hung over from drinking the evening before. Depending on their work performance, coming to work hung over alot might even be grounds for dismissal.