Night time

Hi. I just have a question with regard to Parkinson's. I care for my mother who has it with the last six years. In the last six months, at least two to three times a week she thinks she's dying. It usually happens in middle of night or very early morning. I know some of it is connected to anxiety/panic but I don't think it's totally that. She genuinely believes she's dying, she feels like she can't move or speak and has a general strangeness about her. Even her face kinda changes. She becomes very irrational and just not herself. She won't answer me when I'm talking to her and is irritable. Then when the feeling has passed a few hours later, she's fine and next morning it's like nothing has happened. Just want to know if anyone else has experienced this. She doesn't have dementia. It's quite draining as can go on for half the night/ early morning....Thanks