We've probably seen this in some movies. Once in some kind of sleep, intentionally or unintentionally a character's conscious body leaves his physical body and acts like some spirit.This ability is actually existent. And it is called astral projection. For some, this can be easily done. For others, however, it is rather difficult due to their dear to leave their physical selves.
How do you learn astral projection? Crystal Links will try to tell us how.
Link: Astral Projection - Crystalinks