My 85 year old Mother has been diagnosed with alzheimers. She knows who people are, but she gets confused easily and her short term memory is gone. She is taking aericept. Just over the past 6 weeks she has started shouting out OH! Very loud when she first goes to sleep, then it tapers off, but she will periodically yell throughout the night. It even happens during the day when she appears to be awake and even she is surprised by it. She says, "i must have been dreaming". Any idea what causes this?