Our 5 month old generally gets her head down somewhere in the early evening. We lie the sleeping lump on the bed face up, and she snoozes. Then she rolls over onto her tummy and wakes up. She's at the stage where she's perfectly happy to be on her tummy while awake, if a bit frustrated when trying to crawl (currently she sort of drags herself where she wants to go). However, in the middle of the night, there's normally an exhausted cry for attention, which escalates until we pick her up and either hold her or feed her. At which point she falls asleep again and the cycle continues.
It's driving my slightly-more-easy-to-wake partner to the edge of sanity, and I'd like to save her without joining her on the edge myself.
How can we get our daughter to either not roll over, or to not wake up when she rolls over?
EDIT: An assumption made by most of the answers so far is that she's not sleeping in a cot at the end of the bed. I appreciate that if we move the cot, we "reduce the problem to one that's already been solved", but we're not quite ready for that.