So this happened about five years ago. <blows namechange out of the water> She's been absolutely fine for those five years, but in the past few weeks has had about 6/7 "episodes". What happens is, she'll be asleep in her bed, then she suddenly scrabbles to get out of it, walks a couple of feet, and then sort of faints. She doesn't crash to the ground, she keels over slowly. Her eyes are open, but not focussed. She doesn't froth, shake, pant or become incontinent, she just lies quietly until she recovers. It's never more than a few minutes, then she's back to normal. And it's always when she's asleep, never due to over exertion or whatever.
Other than that, nothing has changed. She's eating, drinking etc as usual, and when the weather is good is positively puppyish when bouncing around outdoors. Her temperament and all other behaviours are still brilliant. Any ideas?