It depends, I go in and out of deep sleep, so it really depends on if what ever happens happens at the right time.

I had gone to sleep at like 6am this morning and at about 9am my boyfriend came to lay down with me and scarred the living hell out of me, basically the sound of him shuffling clothing and just him walking to the bed woke me up, and the first thing I see is him like two feet from my face.

When I'm in a deep sleep nothing can wake me except for falling off the bed.