I don't understand why you are being downvoted- this is an essential question to answer. For instance, Alzheimer's patients show sleep disorder- specifically,

I don't understand why you are being downvoted- this is an essential question to answer. For instance, Alzheimer's patients show sleep disorder- specifically, they tend to not sleep as much as non-Alzheimer's patients. There may be some evidence that this starts before the symptoms of dementia are diagnosed. If it turns out that memory issues cause poor sleep, that could potentially be a big break in early diagnosis.