When Tim was a baby, I remember we were visiting some friends. He fell asleep in his car seat while he was waiting for me to finish talking with my friend before driving away. I realized I needed to change him before letting him spend too much more time--so I pulled him out and as he slept, I changed his clothes. (I don't remember--diaper, removing too many clothes, whatever.) Anyway, I had to pull off his shirt and do quite a bit of disruption; I didn't think a thing of it but my friend was aghast, just sure I would wake him up. I know my Tim, though. I could easily change him and have him sleep through it without even opening an eye.
It's the same today. He's 8 years old and if I have to wake him up, I'd better allow a good while in which to do it. I still could change him if I wanted to and he'd sleep through it. I know for sure that he'll sleep through a smoke alarm buzzing, since if one goes off in our house, they all do--they're wired together. It happened once, while he was asleep. There were at least four within hearing range of his room, all going off as loud as you please, and he was sleeping through it. If there were a fire, his would be the first room I'd run to in order to save anyone helpless, because the others would at least be awake.
Tonight Tim fell asleep on the couch. We needed to wake him to get him off to bed. Katie thought this was an opportunity for great fun. She took his hand and pounded his chest with it repeatedly--to no avail. She made him poke himself in the face, the nose, the ear with his fingers. Still, there is some awareness. I said, "Katie, your nose needs wiping." Well, it wasn't really, of course....but the funny thing was, Tim's hand suddenly grew tense and he wouldn't release it from his chest. Still, it took quite a few minutes to get him to open his eyes and a few more to make him willing to get up and move upstairs. There's deep sleep, and then there's deep sleep. We all have our limits.