My mother pretends to be asleep and then jumps as if startled when we walk by. This happens 40 or 50 times per day. Is this normal?

My mom has fainted since 1960, and now with the alzheimers she will tell us she is going to faint, but then will be out for several hours. Doctors have said as long as she is not unconscience, to leave her along because she just doesn't want to communicate. She will not answer or awaken, but if for example I say I am going to call 911 and take you to the hospital, she will wake up and say no-- so she is hearing me trying to wake her up, just is being stubborn. The wierd thing is that she can be in a very uncomfortable position, and will stay there, and then later say, my arms really hurt (and it was because of the way she is laying) Anyone ever have this along with the sleeping?