Edgar Cayce, What Happens After Death

The death of the physical is birth in the spiritual.  Many souls do not awaken after their physical death.  They have ill prepared themselves for the transition.  Like a child born into the physical, a soul is like a child born into the spiritual.  Gradually it awakens to its surroundings.  The desires of the entity are a portion of its consciousness.  It is unable to move on from the astral plane and goes about its business as if it were still physically alive.  What it craves and desires it goes in search for and often attaches itself to a living being with the same addictions to fulfill its cravings.

Reference~ Edgar Cayce, No Soul Left Behind