Is there any way that you could take the side off the cot and make sure the cot is right up next to your bed (wedged between the wall maybe?)
Ambah, my DP took the side of the cot off and moved the mattress down so it's level with our mattress, then we lock the wheels so the cot does not move. She had been waking up at about 1am and coming in with us when the side was up but last night she slept right through so it's an excellent idea you gave us. THANKS SO MUCH for that suggestion...so grateful to you.

Thanks everyone else for your advices and what has worked for you.