Could this be an early sign of dementia if they to bed very early ,5PM, and gets up at 1AM and starts their day?

Whitney, some people are just night owls. Some like to watch TV into the wee hours of the night, others can't find anything to watch so they go to sleep.

Just curious, who cooks for this elderly person? If the person doesn't do the cooking, then who ever does needs to bump the supper time to a later hour, such as 6 pm.

I just have to ask if there's an outside noise that they can hear about 1 am that wakes them up? We used to have roosters next door that crowed all night. We had to add a white noise maker to mom's room to help her ignore the roosters and dogs and coyotes. Does someone get up with them, or do they get up by themselves?

You might try to change their internal clock by adjusting the bedtime a little later and later in increments. It may take months, but if it works, that would be great.