Originally posted by Kaniaz
I've thought about that before. There's probably some ECG (brainwave) stuff that could show that it's not just any old dream, however.
To again reiterate!

To elaborate on Placabo's point on La'Berges study.
In a controled environment. He was hooked up to Positron emmision tomogrophy (PET) or brain imaging scans. As well as an FMRI. A functional magnectic resonance image. In short, to show what part of the brain was active during his REM period. To prove to the researchers that he indeed was not manifesting this Lucidity and was in fact in control of his actions he predetermined his actions prior to sleep. He set out, opon going to sleep that when he becomes Lucid that he will show his control by moving his eyes back and forth in succession in seperate intervals. Since the eyes are the only physical function that is not subject to sleep paralysis. As the machines had shown just has in any other subject that he was in REM sleep. He performed what he said he was going to do.
Also If you truely had a Lucid dream I feel you would understand conscousness from unconsciousness. I am as subjective as they come and awareness is awareness and control is control. To add to that there are thousands of people who opon having a lucid dream are in concert with one another about its subjectivness.

To still subjectivley see lucid dreaming as an interpretation is intirely valid. For it seems that is what it is. But take into consideration that so to is your waking life.