In his book 50 secrets of Magic Craftmanship (1948), Salvador Dali documented a technique that he called 'slumber with a key'. Sitting in a chair with one arm on the armrest, holding a heavy key over an upside-down plate, he would bring to mind a problem he was working on and allow himself to drift off to sleep. With the onset of sleep, his hand muscles would relax, the key would fall and hit the plate, waking him up, often with a solution to his problem.
