I know exactly how you're feeling. We've gone and done the same. Little Nell, is becoming little Hell. We've allowed her to sleep in the bedroom - as we did our other Cockers - and she is becoming quite unruly...but very loving. She's very good throughout the night and her demands for attention start around 6am. Thankfully, thats the time the OH gets up to walk her.
We've decided that we're gonna stick with it, as its not fair on her, to suddenly make her sleep down stairs. 90% of the time she's fine and a very good girl, it's just a case of waiting for the 10% of evil to fade.