This can be a challenge. She may have the situation that if there is no input, then she will make it. My friends mother would yelp, "Help me, Help me!" and the caregiver would say to her, "What's wrong?" and she would answer, "Nothing" and then yelp, "Help me" when the caregiver left. Giving Ativan or Xanax, just makes the problem worse. I would advise never to use those meds or sleeping pills in elders with dementia. I would treat pain, a long acting Tylenol tab twice a day ( unless liver disease, ask your doctor) is a good start. Sometimes the elder is disinhibited and needs medication to help. That is trickier. We never want to sedate, but sometimes mood stabilizers can help. Good to check B12, that affects memory, nerve function and balance.
Consider REM Sleep Behavior Disorder as a possibility. It can be related to Parkinson's and Lewy Body dementia. Take a look at Mayo Clinic information on the topic.