She's lost the memory of the previous several hours too. This has happened about 4 times. Sometimes she will recover her memory of the previous few hours, but several times she has not. I think she is waking from a deep sleep and is disoriented and confused. It is very disconcerting for her and she is frantic for a while, and then calms down. She doesn't appear to remember to much about it after the event, but when it happens again she remembers that it has happened before. She never slept during the day before, and this usually (not always) happens when she sleeps during the day. Is this something caused by her dementia, her age, something else? Her medications have not changed, so I would rule that out. It's a new development and it is very disconcerting for all.