Dreams are a form of cognitive activity that occur during sleep. Like vivid memories and daytime fantasies, dreams involve visual images in the absence of external visual stimulation. Some dreams are so realistic and well organized that we feel as though they must be real-- that we simply cannot be dreaming this time. Dreaming has always been the subject of controversy. Egyptian papyrus documents dating back to 2000 BC discuss dreams and their interpretations. In ancient Greece the dreamer was believed to be in contact with the gods. In 190 ....