Nikola Tesla slept two hours a night for most of his adult life. His personal journals from the 1890s — held at the Nikola Tesla Museum in Belgrade — describe a precise technique he used to access the hypnagogic state, the threshold between waking and sleep.

Thomas Edison used the same method. Salvador Dalí documented it in 1948. In 2021, a study published in Science Advances by researchers at MIT confirmed the mechanism — people in the hypnagogic state solve creative problems at nearly three times the rate of those fully awake or asleep.