A practice tonight's guest, Von Braschler, has utilized in his work is lucid dreaming. That is the state of consciously being aware that you are dreaming while in a dream, which can be a gateway to all sorts of fascinating experiences. It's a state that one might have spontaneously on occasion, but a bit trickier to have at will.
One induction technique developed by pioneering lucid dream researcher, Stephen LaBerge, is to carry out frequent "reality checks" during the day, with the idea that this routine might carry over into your dream behaviors. Here's how this works. A reality check is simply looking at any object that contains text (i.e. sign, letter, book etc.), then looking away for a couple seconds, and then looking back at the text. If the text hasn't changed, you are not dreaming. The interesting thing about this is, in a dream state, text will rarely stay stable, and when you turn away and look back it will have morphed into something else.
Needless to say, it's a very strange experience when you conduct a reality check in a dream state, and find out you are actually dreaming! Awhile back, when I was on a lucid dreaming kick, I conducted reality checks using a watch with an hourly timer to remind me to do it. Unfortunately, the watch's alarm proved to be a bit of an annoyance in public situations! A more high tech lucid dreaming aid, is the Nova Dreamer(1), a mask you wear while sleeping. It's able to detect when you go into REM (dream state) and notify your dreaming brain to become aware of this by flashing light signals.