Feeling Neglected...

My boyfriend recently got a new job- he works from 6 a.m to 6 p,m, monday through saturday. Obviously, he sleeps a lot- I mean a lot. I understand that he's tired from work, but we don't talk like we used to. It's gotten to the point where sometimes we don't talk for over three days. I've tried to explain to him that us not speaking for such long spans of times bothers me, but he doesn't understand. I think about him all of the time, but I feel like he doesn't feel the same way about me. I mean, if you miss someone, you call and talk to them or visit them. So if he goes for four days without picking up a phone, does he really miss me? He tells me he cares about me, and I believe him, but sometimes i feel unappreciated. We recently had a big arument about this- our first fight, to be honest. He told me that he honestly is just dog tired when he gets off work and he falls out. Is this going to be the one thing that will irritate me in our relationship, or should I try harder to get my point across? Help me out yall!