In Japan it is a standard greeting, for example when you meet someone in the evening and have a drink, when you finished work for the day, when congratulating someone for having finished some project:
お疲れ様です otsukaresama desu
which means something like "you are tired", but is better translated to something like "Good work!"/"You're working hard!"
This greeting is polite and can be used both to people close and not-so-close, as well as your superiors.
On a similar note, in Japan it is actually okay to sleep during meetings, to some extent. There is a specific phrase,
which literally means "present sleep", i.e., the person is sleeping but still present in the sense that if his name is called he will promptly wake up and reply to whatever question he is asked. This is a sign of working very hard, and is therefore not necessarily (depending on circumstances) seen as a bad thing.