Dream Thief — Stephen R. Lawhead

Epic science fiction about alien intervention in human civilization, in which a sleep researcher on an orbiting space station is contacted through his dreams by an alien intelligence bent on the manipulation of humankind. The struggle to prevent this domination takes him to a terraforming project on Mars. There, among the howling winds of a hostile planet, he discovers the decaying remains of an ancient civilization whose demise just might hold the clue to saving humanity.