I'm a very light sleeper. You could not sneak up on me whilst I'm sleeping, because I will wake up at the slightest provocation. I will sometimes get so used to a regular noise that it won't rouse me, but this is far more the exception than the rule.

I think somebody has already mentioned waking up just before an alarm; me too. And, providing it's not a regular wake up time, if I have to be up by 5AM for something, I'll be up alarm or not.

How about you, @Palamon? You made the thread and never answered :P