It's not a good idea to be sleeping in bed with an adolescent and in many states and provinces such behavior would constitute child abuse. I'm not sure if you are talking about a physical or mental disability but even if it is a mental disability that renders the child much "younger' the child's body is still grown up and therefore needs to be respected. Many parents share beds with younger children and this is fine. Perhaps you can encourage your friend to ask a professional about this.  Sarah Chana