Your in some kind of medatative trance. It's like being lucid during a N-REM cycle of sleep. Your eyes are open, because nothing closed them, like normal sleep would push you to do.

The amazing part simply is that you can fall into a trance like that ... comfortably and automatically with your eyes open and without full falling asleep.

Its bascially what happens after you stare into space too long... and have a good imagination.

-Daniel