You might be interested in the work of Thomas Metzinger [0]. He works on consciousness and addresses some of the issues you mention regarding effort & different states that people have experienced/described w/ meditation etc. Eg [1] works towards profiling "pure awareness" experiences among meditators of various stripes. Scroll down to '(3) Peer-reviewed articles' on his page for addl recent research.
He has a dense academic tome called "being no one: the self-model theory of subjectivity" that works through a theory of an 'emergent phenomenological self' [2]. A shorter book discussing the issues is "ego tunnel: the science of the mind & the myth of the self" [3]. It is intended for lay audience & is very readable. fun stuff.