The Lathe of Heaven, by Ursula Le Guin

During a time racked by war and environmental catastrophe, George Orr discovers his dreams alter reality. George is compelled to receive treatment from Dr. William Haber, an ambitious sleep psychiatrist who quickly grasps the immense power George holds. After becoming adept at manipulating George’s dreams to reshape the world, Haber seeks the same power for himself. George—with some surprising help—must resist Haber’s attempts, which threaten to destroy reality itself. Our meeting location is Panera in Porter Square -- usually downstairs.