My mom is 89 years old and has Alzehimer's. She is usually an active person, does the laundry, does a small amount of gardening. She sleeps well, but for the past week, she has been taking 2 hour naps. she says she just feels blah, no energy. This is very unusual for her to take naps. She may snooze a little, but she has never taken naps like this. Of course asking her if anything hurts, she says nothing, but that is part of the disease. What may be causing this change? Thank you for your time.