Taking a nap
If you fall asleep at work, that is usually considered a very bad thing to do in western countries. They look at you like you are lazy and not being productive, it sometimes could result in you losing your job or having to talk to the boss about your poor behavior.
But in Japan, they look at these things differently, and if you fall asleep at your desk it is not a bad thing at all. In fact, they see it more like you were working so hard, that you needed to take a rest to recharge, and that’s okay with them.