| | Deja Vu is a Neurological anomolie
I have a very close friend that did her thesis in nursing school on this very subject and the way she explained it to me made perfect sense. Now if I can regergitate it through my fingers to you in the same fashion, perhaps it will make sense to you.
Unfortunately it has nothing to do with spirit guides, past lives or karma. It's all about stress. If I could remember exactly which part of the brain that interprets space/time (something like the hypothalmus, don't quote me) I could tell you exactly which brain function is impaired by stress.
It works like this. Normally your brain works on autopilot. This is why you don't have to think about breathing or which way to turn in your car when you're going home. And as a special feature, your brain is able to put your critical worries on a (hypothetical) back burner. If you've ever heard the term Psychotic break, you know that the brain loses it's ability to maintain it's integrity and it allows all of your fears to surface like water rushing into a submarine.
Deja Vu is a symptom somewhat like a Psychotic break except instead of losing control of your frontal lobes it sort of blows a breaker. So instead of the present time flowing directly to your brain in sync with your current time/space; there's a slight interuption. So when your brain goes back on line again, it notices your present reality and recalls the exact same reality (before you tripped the breaker) as history. Even though it was the same event.
So although it may seem like you've been there before, the truth is, you were; but it was just a few seconds ago. Not another life, or in an asteral travel or other cool out of body experience.