An interesting question!
One answer would be, in different ways, on different days. How we experience trance is state dependent, meaning whatever state of mind you are in, it can influence the depth, intensity and duration of the trance experience. Essentially, I see it as reaching that nebulous state that exists between emotion and cognition.
We are primarily emotional beings and secondly cognitive ones. We have to make conscious sense of our subconscious processes and much of life's difficulty comes from our subjective interpretation of feeling. One may say "I feel a little apprehensive," another, "I feel terrified." Our linguistic ability to describe feelings accentuates a direct communication (external and internal) between our understanding of words and the inherent implication at the level of emotion. This simply means there is a link between our words and our emotional understanding of them; the same goes for facial expression! Since emotion elicits cognition and cognition elicits emotion, there is an interface between the two. Some scientists believe this to involve a part of the brain called the striatum (caudate nucleus and the putamen).