Charlotte would do this also.
She just grew out of it though - I think it takes them a little while to get the handle of where the sides of the cot are. I wouldn't worry too much, Charlotte stopped waking herself up very quickly.

You can use cot bumpers, just get ones that are only around the top half of the cot, so that there is still airflow.

Sorry don't know how helpful that was lol, as I said we didn't find a 'solution' as such, just waited til she got the knack of being able to move around the cot without scaring herself. (she moves HEAPS in her sleep)