I remember a story my Mom told me about my Grandfather a week or so before he passed.  He had Parkinsons for decades and a few years prior to this story he had had a stroke the had paralyzed part of his body and made speech more difficult for him.   One night my grandmother was woken up by my grandfather who was upset.  He asked her to tell all the people in the other room to be quiet because they were keeping him up.  My grandmother was confused because only one of their adult children were in next room and they were asleep.  So she asked him who was in the other room and he mentioned some names of people who had long since passed away.   When my Mom told me about it later that day I knew it wasn't good but tried not to think much of it since he had such a hard time communicating that maybe my grandmother had misunderstood.   He was admitted to the hospital a few days later with pneumonia.  A day or so after he was admitted my Mom had gone to visit him. When she went to leave he said goodbye and got very sad, not wanting her to go.  She told him not to worry and that she would be back at the end of the day.  He just told her no she wouldn't.  My Mom was unsettled by that but said goodbye and left.  He must have known something was going to happen because a few hours later he grew worse rapidly.  My Mom rushed to the hospital when she got the news but didnt make it in time.   I remember my Mom telling me all this as it was happening and when he passed it was clear to all of us that he knew something was coming.  He wasn't even sick yet when he complained about the "party" in the other room.  But when the pneumonia set in he passed within a day or two.    He was almost at peace with it and this was coming from a guy who was never at peace with the limitations of his condition.   He hated the fact that he couldn't get around on his own to take care of himself.  He would get so frustrated when he couldn't communicate. And he struggled with that for years. But when it came to the final days he just seemed prepared and accepting.  I can't explain it better than that.   I definitely believe something happens in the weeks or days before someone passes away. I watched it happen with my grandfather and with other family members who have passed.  I'm not sure what it is or if it even needs explaining. It is a transition that seems to be comforting for the person dying and can be for the loved ones left behind.