How to begin to overcome the ambiguity present in differentiation between contents and levels of consciousness?

Recently, a welcome trend has emerged - in addition to the traditional studies on contents and states of consciousness, levels of consciousness have become a matter of research. However, there are some conceptual and methodological difficulties with this research - the labels used for empirical measurement of levels are ambiguous and under-specified while the research on neural correlates of consciousness has not been well linked to psychophysical approaches to studying the levels of consciousness. This article suggests a perspective on how to advance the psychophysics of measuring the levels by precisely specifying level-specific contents and how to relate the distinction between contents and levels to the distinction between the underlying brain mechanisms necessary for processing contents and regulating the level of consciousness.