Advice?

Okay so my so is amazing. He has his own daughter he had full custody of who lives with us and were expecting. He’s so excited and attentive and I can’t fault him in anyway.

He works so hard Monday - Friday and every other weekend with every Wednesday off so he’s in work most of the time. Some weeks only had one day off. His day usually starts between 4 and 6 am at work so he has to be up between 2 and 4 everyday. He’s getting little sleep and forcing himself to stay up later for me. I don’t want this. Tonight he went from normal to unable to stand he literally nearly fell backwards from top of stairs. He doesn’t drink but when he’s this level of tired you’d think he was so drunk. He slurs, drips things, staggers when walking. I can’t see it being normal. Some shifts I come home get 2 hours sleep & I still function. Is this chronic exhaustion or sign of something bad. I worry.