Ideally, one learns to sleep very lightly. I've learned since having children and giving up drinking, I can awake at a pin drop unlike in my younger, partying days where I could sleep through an atom bomb.
These days, a cat scratches at the screen door and I'm wide awake. I've got a family to protect (not from the cat, of course).
ESPECIALLY from the cat!
When I was young, I could have slept through anything, drinking or not. Unfortunately, that included alarm clocks and telephone calls.
But, once I had children, I never slept like that again, and my “baby” is 38. Oh, to sleep like that again. I guess it’s not going to happen....