Sleep disorder is common in patients with Alzheimer's disease. Sometimes, a small change in the medication can help. Sometimes we may have to add a different medication to help with the sleep
addressing the specifics of your mother's medical problems or rendering a
medical opinion, the most straightforward way to proceed is seek help from
a sleep specialist. People with Alzheimer's do suffer from sleep
disturbances and this would need to be evaluated by a healthcare
professional. This work up would likely include a sleep study. She would
likely benefit from a sleep center based sleep study as opposed to a home
sleep study, based on her Alzheimer's diagnosis.
Psychology, sleep hygiene is key. Another suggestion would be a medication called trazadone. I would suggest you inquire about the options with the physician overseeing your mother's care and stay away from any medications in the benzodiazepine family. You can find out what these medications are by doing a simple google search.
Some other advice I would give is to take care of yourself as well. All to often we see burnout from caregivers.
I hope this helps.