You do get used to it, thankfully as they get older their waking up diminishes.
Oh wait, not talking about having a newborn baby in the house? Oops sorry!
I do need an alarm, though usually have no issues actually getting up when prompted. I've heard work colleague describing how he needed to set THREE alarms in his phone in order to actually get going in the morning! 2 to 5 minutes apart. Each subsequent disturbance getting him a notch further towards consciousness again! (I picture his getting up being akin to the multiple attempts / glow plug cycles of an old diesel engine on a very cold day! ) I'm thankful I can generally get my facsimile of a functional human being up and running in short order, even at some if the ungodly hours I've needed to do so for long trips away with work.