Fear in my dreams seem to spring from some fundamental causes which I think we all deal with. Fear in the physical world can stem from an immidiate danger which can cause us real bodily harm. Thus the fight or flight reaction. In dreams, I believe, the same thing is happening but on a different level. The dream mind, which may or may not be conscious, perceives a danger within the dream imagery. But, from where does the dream imagery come from? I believe that, at least in my case, the dream imagery comes from the dream mind interpreting the activities of the projected double as it tries to leave the physical body.
A recent dream I've had gives a pretty good example of what I mean: I was hanging from some exposed tree roots over an extremely deep and misty gorge. The trail I had been following was slippery and had an extreme angle tilting toward the chasm. I was holding onto the roots after slipping and was deathly afraid of falling into the alligator-infested waters far below. My feet were kicking upward, trying to hook onto something to save my doomed life. I thought, "I hope I die from hitting the rocks before the croc's can give me the old one-two-three." After this somewhat humorous thought I realized I was dreaming and my awareness popped back into my projectable double which was wildly kicking it's feet and waving it's arms. I was partially stuck in my mid-section and was not able to free myself. Then I woke up after a brief period of unconsciousness.
In past cases I've allowed myself to fall from great heights due to a mild case of lucidity and popped back into my body under intense sensations of vibrational shift which felt like falling.
Is it possible that every dream sensation (this would include good and bad sensations) are due to the dream mind interpreting it's projectable double's attempted projection according to hypothetical physical experiences which may match the psychological trauma? In other words, if the dream mind had the experience and vocabulary to interpret it's projectable double's activities as they were actually happening would we then be able to transfer a copy of our conscious mind to the projectable double more easily?
Maybe the fear that I feel in my dreams are the byproduct of a split mind i.e. the more conscious and lucid I become the less fear-filled my dream imagery becomes and the more I am able to break from the dream scenario into my actual projection experience.
Maybe we need the jarring experience of hanging from great heights over crocodiles to awaken our minds from the dream state.
Is it possible that the more terrifying the dream, the greater the call to lucidity and projection?

*The fear on the face of my dream
is a mirror on the wall of my mind.
I look at myself in the face of an Angel.
My guiding spirit becomes my danger,
I run, leaving progress behind*