Hi and welcome to this caring group where you can always find support and info. I'm a retired mental health RN and think your hubby would be less drowsy in daytime and sleep better at night if the quetiapine was given at approx. 3 pm and 9 pm with an "as needed dose" if he wakes after 2 am....you can call neurologist or your pharmacist re what I'm suggesting. Aricept can sometimes cause agitation if taken at night and can be switched to am but if hubby has been taking it for a long time it likely isn't a problem. It's likely that this sudden change is a fast drop to a more declined Alz stage as the neurologist is saying. Please fill out story portion of your Profile.