I keep Hannah in a large crate and place a comforter over it not only to keep it dark but to also keep her warm. She's in bed at 9:00pm and up at 7:30am. She has potty pads just in case. I also make sure to spend time with her 30 min. before bed time just to tire her out. She's used to her nite nite schedule...
The tech at my vets office recommended I put a cover over her crate and it's worked so far.