Hauntings of the Past
From D&D Wiki
 Hauntings of the Past
You have disturbing Dreams, often reliving past events, often resulting in emotional weakness.
Prerequisite: Must have experienced terrible events in the past.
Effect: You are known to have dark dreams, often representing an unpleasant past event. Every 1d6 days at night (basically once a week at random), the character has an upsetting dream. Upon waking, s/he must succeed a Will save DC 10+Half ECL (1/2 effective character level) or become shaken for the next six hours. In addition on the night of the dream the character must succeed an additional will save of DC 15, or make loud noises (Talking in sleep, or Screaming), this may at DM's discretion wake both the player and/or other party members interrupting their sleep for 1d3 hours.
Roleplaying Ideas: The PC can use this to clue in party members to their past event. Party members who listen to the pc talking in their sleep may figure out clues to the pc's past.