Concern for husband

I need to share this because it's on my heart. My husband has taken over a new responsibility at a firm in town. He is doing a great job and working very very hard; however, it seems like he is way over committing himself and I don't know how to respond. Example: He was at work this morning at 4:30 a.m! It's 10 p.m. and he is still there. He came home for maybe 1 1/2 hours. He says that he needs to do it and there's just not enough help. He doesn't get to claim these hours due to company policy. He usually works late every night at home AND on the weekends too. How much is too much for one person? He says he can't sleep at night because he is thinking of all the tasks to attend to at work. I understand deadlines and some late nights, but how much? Any advice? I just see him working soooo hard and I am trying to encourage him, but it's hard when he's at work, even when he's at home.