She and my dad are in Assisted Living, so most of the bed rails are considered entrapment dangers. I have a bed pillow cut in half and stuck under the mattress, but it really seems like it won't help for long. She just seems to creep feet first out of the bed.
She has a bit of dementia, but is really pretty "with it" yet. And she is mortified if she has to call someone for help. And, of course, dad gets mad at her. Helpful!