According to the online article “The Power of Micro Naps” found here , Salvador Dali learned a technique from the Capuchin monks that allowed him to plumb the mysterious — and fecund — stage of consciousness between sleep and waking known as hypnogogia, and he clearly became quite skilled at mining the hallucinatory images he found there. Dali referred to it as “slumber with a key.” This creative practice or something quite similar has been cultivated by many notable artists, writers, mathematicians and other innovators seeking inspiration throughout the years, reportedly from Thomas Edison to Edgar Allan Poe.
The same article quotes Professor Andreas Mavromatis:
during hypnagogia, the “newer” (evolutionarily speaking), rational parts of the brain are inhibited, while the “older,” more primitive parts (which think in imagery and symbolism rather than words and well-defined concepts), have freer rein. The usual dominance of the prefrontal cortex and its rules of logic are checked, and the typical constraints placed on what’s possible are loosened. Thus, the mind is free to play around, make associations between divergent ideas, and come up with imaginative solution to problems.
Slumber with a Key
The technique involves allowing a descent into Stage I sleep . . . just long enough. This can even be as short as one second. While holding a small but relatively heavy object aloft (arms draped over the side of a chair or bed), the hand and arm muscles will begin to relax, causing that object to drop. . . In Dali’s case, he held a heavy metal key that he would let fall onto a plate, which then produced a loud enough clang to rouse him immediately back into wakefulness. He was then poised to record whatever visions, symbols, insights, or other information that had been waiting at the threshold of consciousness.
Apparently Dali was quite taken with this kind of experimentation, as he is famously quoted as saying,
“One day it will have to be officially admitted that what we have christened as reality is an even greater illusion than the world of dreams.”