ETA - just re-read your post - so it's waking you up, not him ... are you a light sleeper or is he a heavy sleeper? I guess as for bub it would depend on who he / she takes after?....
We're both fairly heavy sleepers, but usually I'll drift off to sleep first and be in a "lighter" part of sleep when his alarm goes off if he's working the early shift (up at 4ish to start at 5). If he's got his alarm on the loud setting like he usually does, it wakes both of us up.

If he's got a later shift, I won't usually be woken by it at all, but he will. It all depends on when we get to sleep and when he's supposed to start. Don't get me started on how I feel when he works overnights!