It doesn't really matter the reason behind the behaviour, if she is going for you in any situation you need to remove the situation.

I agree, I don't like being woken up either but you can't tolerate being bitten or nipped just because you move about in bed. Give her a bed of her own where she can sleep undisturbed.

It's got nothing to do with elevated status/dominance (whatever you want to call it), it's to do with not liking to be disturbed or being startled when asleep.

I do, however, agree that when a dog growls and nips when this happens, you have to make the adjustment and have a 'no sleeping with us in bed' rule.

One of my previous dogs was a tiny Tibetan Spaniel, who would growl and air snap at anyone who woke her up suddenly. Nothing to do with aggression, elevated status or domination, simply a normal reaction of a dog who's been startled awake. Something she only did during the day, but not during the night when she'd sleep snuggled up next to me in bed.

I always asked anyone visiting my house that when Chloe was asleep if they wanted her to move off the sofa,not to touch her but to talk to her quietly until she was fully awake before telling her to move.

Dont buy that - neither Hal, Tai nor Ben liked to be suddenly woken up but never would either of them have air snapped.

All dogs are different and have different levels of tolerance to a variety of things.

Not only do they have different tolerance levels, but also different ways of reacting once their level has been reached

Snapping is aggressive whatever the reason behind it.

Exactly, and is not to be tolerated under any circumstances IMO.

I agree with you, Lyndsay if she is asleep or semi asleep then she is be reacting defensively . Also , as yo said , you yelled at her when she did it so this would make her more jumpy and defensive .
has she had a health check for arthritis etc .

Agree though that the dogs need to be kept out of your bed.

It's a warning though and a natural behaviour .