Art by smbc-comics
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.
Pubmed Articles
Does Consciousness Disappear in Dreamless Sleep?
Sciencealert Article We Were Wrong About Consciousness Disappearing in Dreamless Sleep, Say Scientists
Threshold has changed, the definition is still the same, we’re just getting better at reverting the stop of some activities, like breathing or heartbeat. If we someday could revert neuronal depolarization, that would be great, but it seems difficult to achieve.
The other part is not just philosophy, it’s the best we can do to define a “self”. The philosophical part is only whether we can consider them a continuum, or whether we have to see them as usually similar but separate (there are reasons to support both versions).
If the threshold changed, the actual definition changed. The same words to describe a different point. If the definition described two different things, its changed. That’s basic and simple reasoning. If a definition no longer describes the same thing, it’s because it’s actual meaning has changed.