I bought my wife one of those large, digital clocks that tells the time of day, day of week and date. Unfortunately, her ALZ has progressed past the point where she can read even this simple display. She gets up when she wants to and a clock would not stop her even if she was capable of reading it. She is operating by her own rules without regard to the customary hours of sleep.

I got my husband a large digital clock very easy to read.

I don't know if it will work but there is a clock you can get for kids that you can set with lights. If the light is red - time to stay in bed. If it is green you can get up. (Not sure if I stated the colors right.)