I think my coworkers do not sleep ...

I just can't figure it out..I have been working a minimum of 12 hours a day, sometimes more, and I am still the first one to go home! Do Japanese workers sleep? I really don't know if they do. And they arent in a bad mood or complain about it either! Its kind of freaking me out. I am so tired and they all seem fine. I don't get it. I guess I will get used to it (I hope. I knew asians were hard workers, but this I had no idea. I feel like a wuss ...sigh