Feel like he doesn't care about me?

My boyfriend does this thing that really irritates me & kind of makes me feel like he doesn't care about me. He's always either falling asleep while we're texting, in the middle of a conversation or stops replying for hours, sometimes not even replying until the next day until I text him AGAIN. He does this almost every day & he's done it ever since like the first month of dating. He sleeps so damn much, I actually think he might have narcolepsy. It doesn't matter if it's day or night or if he has the day off from work. He'll still stop replying or fall asleep. Usually if he stops replying for several hours or even until the next day, he won't even have an excuse, no apology or anything. It just makes me feel like he doesn't even care about me, especially when he knows it upsets me. Am I overthinking things or would y'all be upset too??