For example, when Thomas Edison had a problem to solve, he would often attempt to "fall asleep" at his desk with ball bearings clutched in each hand. Just as he was about to "drop off," the ball bearings would fall to the floor activating him, and he would often return from the drowsy state with an image of the problem solution. Theta occurs in abundance in that delicious state just on the verge of sleep that most of us a familiar with. It is often difficult to recapture the images that occur in association with theta as we move to normal waking consciousness, yet it can be useful to develop this skill.