Sleepwalking and bathroom accidents. Any advice?

I sure would consult the doctor about this. It is strange but it seems that any underlying sleep problems greatly affect. My brother was diagnosed with probable early Lewy's Dementia. Almost all his hallucinations came at night after trip to bathroom and were very interesting, detailed and remember and described by him in details. He was up and awake but in some state. Would see things out the window that became whole "garden parties". He had for many years that thing with sleep where he acted out in his sleep. Being in the same bed with him could end you up getting slugged if he had a bad dream. He would push himself out the bed, fleeing. Would kick in his sleep. The docs said some percentage of people have a thing where the ability to inhibit the body acting out dreams was just not there, some were sleepwalkers.
This is such a unique problem. I wonder if it would help to consult with anyone doing sleep studies in your area dependent on where you are. As to what to DO about it, I think they don't really have anything that would work, but I sure will follow this thread and hope there is some information.

If you don't want him to strip off his brief, you can consider "adaptive" clothing (specifically "anti-strip" suits) so that he won't be able to do that.

I would suggest rather than you asking "are you awake, do you know where you are" that you get up with him and help him.