That is when you are on your way to lucid dreaming. When this happens to me sometimes i fel pain in the centre of my chest follow by what is called a torso rush, you feel a tremendous rush of energy through your body, and sometimes the palms of your hands glow. I think you aura can leave your body through the palms of your hands, anyway when this happens, which is rarely unfortunately, I have what i beleive could be out of body experiences.