[kylebrown]

I remember reading about a famous inventor (can't remember who, sorry) who purposefully induced this state by holding something in his hand which would make a noise when let go. While falling asleep, the object (say, a metal ball) would drop (into say, a metal bowl), making enough noise to wake him up just as he was falling asleep. If an idea came he would write it down, if not he would repeat the process.

[epikur]

Salvador Dali:

http://www.arthurmag.com/2010/06/25/diy-magic-dropping-the-s...

The comments on that mention Thomas Edison also doing something similar.