Unexpected and sudden astral travel.

This is the story of a gentleman who was sleeping and had to get up to open the door of his house, because heard somebody was knocking. When he returned to bed, he was very surprised to find a man on the bed. When watching carefully, he realized that the man on the bed was his own body, which stayed on the bed.

From this story, you could realize that when a man gets up and leave the bed at the moment when he's dozing, the "astral travel" happens.

The gentleman of the previous case, was able to astral travel because he got up and leave the bed without thinking, reasoning or mental analysis, there were neither fears, nor prejudices. He got up to open the door on the spot, and that was it.