When an overnight home aide is there to care for a patient with dementia, what happens if that patient shares a room with their spouse?

Have you asked the caregiver and stepdad how they think this should work?

Personally, I would start by putting a baby monitor next to mom, have the aid in a different room and respond to the monitor as needed. Then they can adjust the arrangement until they find what works best. I wouldn't close the bedroom door all the way.

Dementia is ever changing, so having a caregiver that understands that will help keep things flexible enough to keep working as the disease progresses.

deemer76: Separate sleeping quarters are required for the couple - UNLESS it would be too traumatizing for the patient with dementia to sleep alone. Perhaps the patient would be too upset after having had her spouse by her side at night for xxxx number of days/years.

They will need separate rooms. One with a set of twin beds for mom and caregiver. Dad can keep the room he used to share with mom.

Two separate rooms, problem solved.

The caregiver is there to care for mom.
If the caregiver hears mom, either through the door or via monitor (probably a better idea) the caregiver enters the room and takes mom to the bathroom and then walks mom back to the bedroom and helps her back into bed. If mom just needs a glass of water the caregiver can bring it. If spouse is a deep sleeper none of this would probably wake him.
There may be a time when getting mom up to walk to the bathroom is a bit more difficult and either a Sit to Stand would be needed or a bedside commode would be safer, or even changing her while she is in bed is a possibility. At that point a separate bed might be easier or a separate room. If they are not at that point now it might be a discussion that should be brought up for the near future.

You're perplexed because the logistics do not work well. It would probably be best for your mom to be in her own room (or better for her spouse to go into another room) when the aide is there. Seems very awkward for an aide to go into a room where another person is sleeping. I wouldn't want to do it.