It is said that Thomas Edison hardly slept. Instead he took frequent cat naps during his 16-hour work day. He used these naps to access answers to troubling questions he had about his experiments because he believed the answers would come to him while sleeping. To make sure he'd be able to "capture" these answers he'd go to sleep with a rock in his hand. Once he reached deep sleep the rock would slip from his hand awakening him with the answer fresh in his mind.
