It sounds as if your father is having a memory regression of having a cold. Because of the dementia, he is hallucinating that he is sick. You should watch him closely in this case and have him evaluated by a doctor if he really does start to exhibit symptoms of a cold such as sneezing, fever, chills, pain, etc...The sleeping is probably due to depression. Many patients with frontal lobe dementia have a tendency to become chronically depressed and this will cause him to sleep a lot. Try providing his with activities that he can participate and be active in. This will help with the depression.