Marlene - DS has rolled off in the night. I lay pillows by the side of the bed to cushion the fall, so rolling off wakes him (usually....) but he's not hurt or too shocked. Also, it's a queen-size mattress so plenty of room for him to roll around (though it's still not big enough for him some nights). A single & cot one next to it might be alright. Hope you get some good results.