My father has severe dementia and most of the time he sleeps or is up all day and night fidgeting. He is bedridden. Today, his caregiver and I tried to change him but he fought us every step of the way. He was kicking his legs, punching, and yelling. I held him with all my might so the caregiver would not be hurt. My father appeared to have superhuman strength. How can a severely demented person suddenly appear so strong?