I know that they say to make as much noise as possible to try and show your dominance, but what happens if I am sleeping? If I wake up with a bear right outside my tent while i'm sleeping, and I have nothing to defend myself with, what should I do?
Making noise is useful when walking in a forest to tell the animals that you're coming. They probably retreat to safe distance when they hear your voice. However, when you're sleeping, you should avoid making sudden moves or sounds. Move slowly and talk calmly if you want to. The animal probably smells you, so it's no surprise that you're nearby. Startling it might give the impression that you're hostile.
My suggestion is to stay still and observe what the bear is doing. Don't turn your back to it especially if it has visual contact. Turning away, making sudden moves or fleeing might trigger a "hunting instinct" (there's probably a better translation) in the animal, making it maul you even if it originally doesn't want to hurt you.
So the bear probably smells your presence. And if it sees you? Playing dead is not recommended anymore at least where I live. The animal might get confused and try to claw or gnaw you. It's better to sit in a low squatting stance, probably leaning a bit forward. Again not turning your back to the animal.
There's a difference to sounds you can make. I've noticed that a continuous chatter is less annoying to animals than sudden snorts. Snorting might startle animals, while talking appears to make them lose interest in you. Maybe they know that people don't talk when they're alone.