I had 2 friends who had this experience. They told me that it happened when they were about to be baptise.

I also had this experience, only once. After visited my ex-class mate’s wake, he died of leukemia; he was well like, well behaved person. When at the wake, I was thinking to myself, “what would happened to him, will he go heavel or hell”. Later that night, when I was sitting on my bed, heard knocking on main door. opened and found no one. That night, when sleeping, suddenly woke unable to move a muscle, unable to should. I used all my strength I had and shouted God to help me – I was free from this force. Immediately, I had this impression in my mind, it was this late friend, he visited me because he want me to pray for him to go heaven.

I prayed for him. This happended more than 20 year ago, I still pray for him once a while.

http://www.spiritlessons.com/hisr_video_transcript.htm