Recently, about once or twice a week my wife who has Alzheimer's will go to bed as normal about 11.00pm and fall into a deep sleep for 15-20 hours (without medication or need to go to the toilet). Last night was the same, she went to bed at 11.00pm and is still asleep now at 3pm. I woke her at 12.30pm and got her up but she did not want to go to the toilet or have a cup of tea or anything, she just wanted to go back to bed. Another day she will be wandering about every few hours during the night but be bright and happy all day; there is no pattern but these extended sleeps are new. Has anyone else had similar experience? A sad consequence of this is that our 5 year old American Spaniel who sleeps on her bed won't budge until she gets up. Treats and encouragement to go for a walk are all ignored and he just sleeps beside her.