My mother has Alzheimer's and is sleeping 14 to 18 hours a day

lilly, sleeping for long periods of time does not necessarily mean that your dad has Alzheimer's. His sleepiness could be related to something else. However, it is quite normal for one with advanced Alzheimer's to sleep for longer and longer periods of time. ALzheimer's is a terminal disease.The brain becomes bogged down with these horrible "fibers" and this gradually causes the sufferer to basically forget how to do everything,including staying awake and in the end even breathing. Carol, is your mom on any Alzheimer medications? Perhaps there is something that could help her.
You must remember to always be patient with Alzheimer sufferers. They can't help themselves. I have learned to enjoy the moments that my dad is awake. But when all he wants to do is sleep i let him do just that. Of course i will wake him for meals. He will stay awake for coffee and cookies too! Bless his heart.

My dads 85 and sleeps 20 hours a day.. I didnt know that was a sign of alzheimers...

From what I understand about Alzheimer's, sleeping for longer periods of time are quite common when the person is entering into a later stage. My mother sleeps a lot more than she used to. She eats less, has withdrawn from many of her favorite activities, cannot even get down to retrieve the mail on most days anymore....and she's only 75.
We call or visit her at times when we know she will be awake and we encourage her at that point to get up and move around. She will get up for the bathroom, some meals, and loves to watch the news.
Since we can't get inside her head to know what is happening, we do what we can to help and what she can handle on that given day.

she maybe a little depressed, I would talk to her doctor. But my mother in law was the same way, we put a tv in her room and she will watch it instead of sleeping.