"During the late nineteenth century it was generally believed by dream theorists that dreams were very brief, usually in reaction to an internal or external stimulus, or even that they occurred during the process of awakening. Freud (1900) tried to blend these perspectives by comparing dreams to "a firework that has been hours in the preparation, and then blazes up in a moment." He agreed that they last for only a brief time, and perhaps occur only during awakening, but added the idea that the thoughts underlying dreams develop slowly during the day. However, contrary to Freud, laboratory studies reveal that dreaming takes place longer, more frequently, and more regularly than he or any other theorist ever imagined before the serendipitous discovery of sleep stages in 1953 (Aserinsky & Kleitman, 1953; Dement, 1955; Dement & Kleitman, 1957)."