Consciousness is often said to disappear in deep, dreamless sleep. We argue that this assumption is oversimplified. Unless dreamless sleep is defined as unconscious from the outset there are good empirical and theoretical reasons for saying that a range of different types of sleep experience, some of which are distinct from dreaming, can occur in all stages of sleep.
I think I know what you mean, but plenty of terms have relative definitions ("behind", "bright", "x+1", "etc"... etc). If you're looking for an absolute point, you won't find one, because their meaning is the relationship itself.
Both "life" and "death" define a state relative to another. The definition of "life" is a particularly tricky one, because it includes multiple relative definitions like "growth", "reaction", "functioning", and a "reproduction" that includes both cloning and "imperfect" cloning. Being "death" the opposite, it's necessarily as relative and tricky too.
